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Classifications

Harrison's Chapter

📘

Definitions

1

SCORTEN Severity-of-Illness Score

SCORTEN (SCORe of Toxic Epidermal Necrosis) is a validated 7-parameter prognostic severity-of-illness score for SJS/TEN that predicts hospital mortality. Each parameter present scores 1 point. Total score 0-1 predicts ~3% mortality; score 2 predicts ~12%; score 3 predicts ~35%; score 4 predicts ~58%; score ≥5 predicts >90% mortality.

DIAGNOSTIC_CRITERIA Adults with SJS, SJS/TEN overlap, or TEN admitted to hospital; validated for mortality prediction

SCORTEN parameters (7 independent risk factors for death)

Seven independent risk factors for death, each scored 0 (absent) or 1 (present). Parameters: (1) age >40 years, (2) malignancy, (3) tachycardia >120/min, (4) initial epidermal detachment >10% BSA, (5) serum urea >10 mmol/L, (6) serum glucose >14 mmol/L, (7) bicarbonate <20 mmol/L.

Show evidence (1 reference)

PMID:10951229 SUPPORT Human Clinical

"We identified seven independent risk factors for death and constituted the toxic epidermal necrolysis-specific severity-of-illness score: age above 40 y, malignancy, tachycardia above 120 per min, initial percentage of epidermal detachment above 10%, serum urea above 10 mmol per liter, serum..."

Bastuji-Garin et al. (2000) developed and validated SCORTEN using 165 patients (development) and 75 patients (validation), demonstrating excellent calibration (ROC area 82%) for predicting hospital mortality in TEN/SJS.

Show evidence (1 reference)

PMID:10951229 SUPPORT Human Clinical

"This study demonstrates that the risk of death of toxic epidermal necrolysis patients can be accurately predicted by the toxic epidermal necrolysis-specific severity-of-illness score."

Bastuji-Garin et al. (2000) developed and validated SCORTEN using 165 patients (development) and 75 (validation), demonstrating excellent calibration and discrimination for predicting hospital mortality in TEN/SJS.

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Subtypes

2

SJS/TEN Overlap

Intermediate form with 10–30% body surface area epidermal detachment, sharing features of both Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis.

Show evidence (1 reference)

PMID:29188475 SUPPORT Human Clinical

"The difference between SJS, SJS/TEN overlap, and TEN is defined by the degree of skin detachment: SJS is defined as skin involvement of < 10%, TEN is defined as skin involvement of > 30%, and SJS/TEN overlap as 10-30% skin involvement."

This comprehensive review defines the SJS/TEN spectrum classification by degree of epidermal detachment, supporting the intermediate SJS/TEN overlap subtype category.

Drug-Induced SJS

The predominant form, triggered by medications including anti-infective sulfonamides, anticonvulsants (carbamazepine, phenytoin, lamotrigine), allopurinol, oxicam NSAIDs, and nevirapine. Risk is greatest within the first two months of drug exposure.

Show evidence (2 references)

PMID:7477195 SUPPORT Human Clinical

"Among drugs usually used for months or years, the increased risk was confined largely to the first two months of treatment, when crude relative risks were as follows: carbamazepine, 90 (95 percent confidence interval, 19 to infinity); phenobarbital, 45 (19 to 108); phenytoin, 53 (11 to infinity)"

This landmark NEJM case-control study quantified the drug-specific relative risks for SJS/TEN, establishing carbamazepine, phenytoin, sulfonamides, and allopurinol as the highest-risk medications, and the first two months of exposure as the critical risk window.

PMID:29188475 SUPPORT Human Clinical

"Drugs with a high risk of causing SJS/TEN are anti-infective sulfonamides, anti-epileptic drugs, non-steroidal anti-inflammatory drugs of the oxicam type, allopurinol, nevirapine, and chlormezanone."

Lerch et al. (2018) provides a current enumeration of high-risk causative drugs, corroborating the drug-induced nature of SJS as the predominant form.

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Pathophysiology

11

HLA-Mediated Genetic Susceptibility

Specific HLA class I alleles are strongly associated with SJS/TEN triggered by particular drugs in specific ethnic populations. HLA-B*15:02 confers extremely high risk of carbamazepine-induced SJS/TEN in Southeast Asian populations (odds ratio 2504); HLA-B*58:01 predisposes to allopurinol-induced SJS/TEN; HLA-A*31:01 confers risk of carbamazepine-induced SJS/TEN in Northern European populations (OR 25.93). These alleles act as the upstream genetic determinant that enables aberrant drug presentation and is the entry point of the SJS/TEN causal cascade.

HLA-B link HLA-A link

antigen processing and presentation of peptide antigen via MHC class I link

Downstream

Drug-HLA Direct Interaction Risk HLA alleles physically present the parent drug (or a reactive metabolite) in their peptide-binding groove, generating the molecular trigger for CTL activation.

Show evidence (3 references)

PMID:29793265 SUPPORT Human Clinical

"In the case of carbamazepine-induced SJS/TEN, the tight association of the HLA-B*1502 allele (sensitivity 100%, specificity 97% and odds ratio 2504) provides a plausible basis for further development of such a test to identify individuals at risk of developing this life-threatening condition."

Hung, Chung and Chen (2005) demonstrated that HLA-B*1502 has near-perfect sensitivity and specificity for carbamazepine-induced SJS/TEN in Asian populations, anchoring the genetic root of the SJS/TEN pathograph.

PMID:22541332 SUPPORT Human Clinical

"The patho-mechanism involving HLA-restricted presentation of a drug or its metabolites for T-cell activation is supported by the findings of strong genetic associations with HLA alleles (e.g. HLA-B*15:02 and carbamazepine-SJS/TEN, and HLA-B*58:01 and allopurinol-SJS/TEN)."

Chung and Hung (2012) review confirms the HLA allele associations for both carbamazepine (HLA-B*15:02) and allopurinol (HLA-B*58:01) as genetic determinants of SJS/TEN susceptibility.

PMID:21428769 SUPPORT Human Clinical

"The presence of the HLA-A*3101 allele was associated with carbamazepine-induced hypersensitivity reactions among subjects of Northern European ancestry."

McCormack et al. (2011 NEJM) extended the HLA risk-allele model to European populations, identifying HLA-A*31:01 as a strong determinant of carbamazepine- induced SJS/TEN (OR 25.93) and broadening the genetic-susceptibility node beyond Han Chinese HLA-B*15:02.

Drug-HLA Direct Interaction

The causative drug (e.g. carbamazepine, allopurinol metabolite oxypurinol) binds non-covalently to the antigen-binding groove of the risk HLA class I molecule on antigen-presenting cells and keratinocytes, without requiring intracellular processing or covalent haptenation. This "p-i concept" (pharmacological interaction with immune receptors) generates a neoantigen-like surface that engages drug-specific T cell receptors. Allele-specific drug binding explains why a single drug triggers SJS only in carriers of a particular HLA allele.

antigen processing and presentation of peptide antigen via MHC class I link

Downstream

Drug-Specific Cytotoxic T Cell Activation Surface display of the drug–HLA complex licenses recognition by drug-specific CD8+ T cell receptors and triggers clonal expansion of effector CTLs.

Show evidence (1 reference)

PMID:22322005 SUPPORT In Vitro

"The endogenous peptide-loaded HLA-B∗1502 molecule presented CBZ to CTLs without the involvement of intracellular drug metabolism or antigen processing."

Wei and Chung (2012) elucidated the molecular mechanism of HLA-B*15:02-mediated carbamazepine presentation, showing direct drug interaction with HLA bypassing conventional antigen processing — the canonical molecular evidence for the p-i model in SJS/TEN.

Drug-Specific Cytotoxic T Cell Activation

Drug antigens (or reactive metabolites) presented via the risk HLA class I molecule are recognized by drug-specific CD8+ T cell receptors, initiating a type IVc delayed hypersensitivity reaction with robust drug-specific CTL expansion directed against keratinocytes. Activated effector T cells traffic to skin and mucosa, where they encounter HLA-presenting keratinocytes and deploy cytotoxic effector programs (granulysin secretion, Fas-FasL engagement, perforin/granzyme delivery, and pro-inflammatory cytokine release).

CD8-positive cytotoxic T cell link

T cell mediated cytotoxicity link antigen processing and presentation link

Downstream

Granulysin-Mediated Keratinocyte Apoptosis Activated drug-specific CTLs and their NK-cell partners secrete granulysin into the dermoepidermal junction, the dominant effector molecule causing disseminated keratinocyte death.

Perforin/Granzyme B-Mediated Cytotoxicity Drug-specific CTLs release perforin/granzyme B into the immunological synapse with keratinocytes, an MHC class I-restricted contact-dependent killing modality that operates alongside granulysin.

Fas-FasL Keratinocyte Apoptosis Activated PBMCs (including drug-specific CTLs) shed soluble FasL that engages keratinocyte Fas and triggers extrinsic-pathway apoptosis as a parallel effector arm.

IL-15 Cytokine Amplification Activated CTLs and the inflammatory milieu produce IL-15, which feeds back to enhance NK and CTL cytotoxic capacity and correlates with SJS/TEN severity and mortality.

Lipocalin-2 / NETosis Innate Amplification Skin-infiltrating CD8+ T cells release lipocalin-2 in a drug-specific manner, triggering neutrophil extracellular trap (NET) formation in early lesional skin and bridging adaptive activation to an innate amplification loop.

Show evidence (4 references)

PMID:15536433 SUPPORT In Vitro

"Blister cells also killed IFN-gamma-activated autologous keratinocytes in the presence of drug in the 2 patients tested. Blister cells showed a strong immunoreactivity for granzyme B, and cytotoxicity was abolished by EGTA, but not by anti-Fas/CD95, suggesting perforin/granzyme-mediated killing."

Nassif et al. (2004) directly demonstrated that drug-specific CD8+ CTLs are the effector cells in TEN/SJS, killing autologous keratinocytes in a drug-dependent manner via perforin/granzyme pathways.

PMID:22322005 SUPPORT In Vitro

"The endogenous peptide-loaded HLA-B∗1502 molecule presented CBZ to CTLs without the involvement of intracellular drug metabolism or antigen processing."

Wei and Chung (2012) elucidated the molecular mechanism of HLA-B*15:02-mediated carbamazepine presentation, showing direct drug interaction with HLA bypassing conventional antigen processing — explaining why this reaction affects genetically susceptible individuals independent of drug metabolism.

PMID:39379371 SUPPORT Human Clinical

"Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) is a rare but life-threatening cutaneous drug reaction mediated by human leukocyte antigen (HLA) class I-restricted CD8+ T cells."

Gibson et al. (2024 Nat Commun) — multi-omic single-cell sequencing of 109,888 cells from 15 SJS/TEN patients — provide contemporary transcriptomic confirmation that HLA class I-restricted CD8+ T cells drive SJS/TEN, anchoring this node in current single-cell evidence.

+ 1 more reference

Granulysin-Mediated Keratinocyte Apoptosis

Activated CD8+ CTLs and NK cells release granulysin, a 15-kDa secretory cytotoxic protein, which is the dominant effector molecule causing widespread keratinocyte death in SJS/TEN. Granulysin concentrations in blister fluid exceed perforin, granzyme B, and soluble FasL by two to four orders of magnitude, making it the single most important mediator of disseminated keratinocyte death.

keratinocyte link natural killer cell link

GNLY link

keratinocyte apoptotic process link T cell mediated cytotoxicity link

Downstream

Confluent Epidermal Necrosis and Detachment Granulysin-induced keratinocyte death across the basal layer collapses epidermal-dermal adhesion, producing the confluent full-thickness necrosis and skin detachment that define SJS.

Show evidence (2 references)

PMID:19029983 SUPPORT Human Clinical

"Granulysin concentrations in the blister fluids were two to four orders of magnitude higher than perforin, granzyme B or soluble Fas ligand concentrations, and depleting granulysin reduced the cytotoxicity."

Chung et al. (2008) demonstrated that granulysin is the dominant cytotoxic mediator in SJS/TEN blister fluid, far exceeding other cytotoxic molecules, and that its depletion reduces cytotoxicity — directly establishing it as the key effector molecule.

PMID:19029983 SUPPORT Human Clinical

"blister cells from skin lesions of SJS-TEN primarily consist of cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells, and both blister fluids and cells were cytotoxic. Gene expression profiling identified granulysin as the most highly expressed cytotoxic molecule"

Chung et al. (2008) showed that CTLs and NK cells are the dominant blister cells and granulysin is the most highly expressed cytotoxic molecule, identifying the cellular and molecular effectors.

Fas-FasL Keratinocyte Apoptosis

Soluble FasL (sFasL) secreted by peripheral blood mononuclear cells (PBMCs), not by keratinocytes themselves, binds Fas (CD95) on keratinocytes and triggers apoptosis via the extrinsic caspase pathway. Elevated serum sFasL levels are detected in both SJS and TEN patients compared to controls, and sFasL may serve as an early diagnostic biomarker. This pathway acts alongside granulysin as a secondary mechanism of keratinocyte killing.

keratinocyte link

FAS link FASLG link

keratinocyte apoptotic process link extrinsic apoptotic signaling pathway via death domain receptors link

Downstream

Confluent Epidermal Necrosis and Detachment Fas–FasL extrinsic apoptotic signalling adds a parallel apoptotic load to keratinocytes, contributing to the collapse of the epidermis and skin detachment phenotype.

Show evidence (1 reference)

PMID:12707034 SUPPORT Human Clinical

"Taken together, these results indicate that sFasL secreted by PBMCs, not keratinocytes, plays a crucial role in the apoptosis and pathomechanism of TEN and SJS, and that the serum sFasL level may be a good indicator for the early diagnosis of TEN and SJS."

Abe et al. (2003) demonstrated that soluble FasL secreted by PBMCs (not keratinocytes) drives keratinocyte apoptosis, with high sFasL levels in SJS and TEN patients versus controls — establishing Fas–FasL as an independent apoptotic pathway from granulysin.

Perforin/Granzyme B-Mediated Cytotoxicity

Alongside granulysin, drug-specific CD8+ CTLs kill keratinocytes via the perforin/granzyme B pathway. Blister fluid lymphocytes display cytotoxic phenotype (CD8+HLA-DR+CLA+CD56+) and kill drug-sensitized keratinocytes; granzyme B immunoreactivity is intense in blister cells, and cytotoxicity is abolished by EGTA (a perforin inhibitor) but not by anti-Fas, demonstrating perforin/granzyme as an independent killing modality distinct from Fas–FasL.

CD8-positive cytotoxic T cell link

PRF1 link GZMB link

T cell mediated cytotoxicity link keratinocyte apoptotic process link

Downstream

Confluent Epidermal Necrosis and Detachment Perforin pore formation followed by granzyme B delivery initiates intrinsic apoptosis in keratinocytes contacting drug-specific CTLs, contributing contact-dependent killing to the final epidermal necrosis output.

Show evidence (2 references)

PMID:15536433 SUPPORT In Vitro

"These results strongly suggest that drug-specific, MHC class I-restricted, perforin/granzyme-mediated cytotoxicity probably has a primary role in TEN."

Nassif et al. (2004) demonstrated that drug-specific perforin/granzyme B-mediated cytotoxicity is an independent killing modality in SJS/TEN, complementing granulysin as an effector mechanism.

PMID:22541332 SUPPORT Human Clinical

"Fas-FasL and perforin/granzyme B have been advocated mediating the epidermal necrosis in SJS/TEN. Our recent study showed that granulysin, a cytotoxic protein produced by CTLs or natural killer (NK) cells, is the key mediator for disseminated keratinocyte death in SJS/TEN."

Chung and Hung (2012) describe the hierarchy of cytotoxic mechanisms in SJS/TEN, placing perforin/granzyme B alongside granulysin as an effector of epidermal necrosis.

IL-15 Cytokine Amplification

Serum interleukin-15 is markedly elevated in SJS/TEN and correlates with both disease severity (SCORTEN) and mortality. IL-15 acts as an amplifier in the cytotoxic loop: it potentiates the killing capacity of NK cells and blister- derived T cells, increasing the cytotoxic output of upstream CTL/NK effectors against keratinocytes. IL-15 thus links T-cell activation to enhanced granulysin/perforin-mediated keratinocyte killing and provides a candidate therapeutic target.

natural killer cell link CD8-positive cytotoxic T cell link

IL15 link

cytokine-mediated signaling pathway link natural killer cell mediated cytotoxicity link

Downstream

Granulysin-Mediated Keratinocyte Apoptosis IL-15 enhances NK and CTL cytotoxic capacity, increasing release of granulysin and other cytolytic granules into lesional skin and amplifying disseminated keratinocyte killing.

Perforin/Granzyme B-Mediated Cytotoxicity IL-15 sensitises CTLs and NK cells, raising perforin/granzyme delivery into keratinocyte synapses.

Show evidence (2 references)

PMID:28011147 SUPPORT Human Clinical

"the levels of IL-15 (r = 0.401; P < 0.001) and granulysin (r = 0.223; P = 0.026) were significantly correlated with the disease severity in 112 samples after excluding patients with insufficient data to calculate the score of TEN."

Su et al. (2017 J Invest Dermatol) showed that IL-15 levels correlate with SJS/TEN severity (SCORTEN) and mortality, identifying IL-15 as an amplifier cytokine and prognostic biomarker.

PMID:28011147 SUPPORT Human Clinical

"IL-15 was also associated with mortality (P = 0.002; odds ratio, 1.09; 95% confidence interval, 1.03-1.14; P = 0.001; adjusted odds ratio, 1.10; 95% confidence interval, 1.04-1.16)."

Su et al. (2017) quantified the mortality association of IL-15 in SJS/TEN, anchoring it as a clinically relevant amplification node.

Lipocalin-2 / NETosis Innate Amplification

Drug-specific CD8+ T cells in early lesional skin secrete lipocalin-2, which triggers neutrophil extracellular trap (NET) formation by infiltrating neutrophils. Neutrophils undergoing NETosis release the antimicrobial peptide LL-37, which induces formyl peptide receptor 1 (FPR1) expression on keratinocytes. FPR1 expression renders keratinocytes susceptible to necroptosis, creating a self-amplifying loop because necroptotic keratinocytes in turn release LL-37 and propagate FPR1 induction in neighbouring cells. This NETs–FPR1–necroptosis axis is specific to SJS/TEN and not seen in milder cutaneous adverse drug reactions.

neutrophil link keratinocyte link

neutrophil extracellular trap formation link

Downstream

Annexin A1-FPR1 Keratinocyte Necroptosis LL-37 released during NETosis upregulates FPR1 on keratinocytes, priming them for annexin A1-mediated necroptosis and amplifying epidermal cell death.

Show evidence (2 references)

PMID:34193610 SUPPORT Human Clinical

"We describe a mechanism by which neutrophils triggered inflammation during early phases of SJS/TEN."

Kinoshita et al. (2021 Sci Transl Med) defined neutrophils and NETosis as innate-immune amplifiers in early SJS/TEN lesions, linking adaptive CTL activation to keratinocyte necroptosis.

PMID:34193610 SUPPORT Human Clinical

"FPR1 expression caused keratinocytes to be vulnerable to necroptosis that caused further release of LL-37 by necroptotic keratinocytes and induced FPR1 expression on surrounding keratinocytes, which likely amplified the necroptotic response."

Kinoshita et al. (2021) describe the self-amplifying necroptosis loop in which dying keratinocytes propagate FPR1 induction in neighbours, supporting the spreading-necrosis output of SJS/TEN.

Annexin A1-FPR1 Keratinocyte Necroptosis

Annexin A1 released by drug-exposed PBMCs binds formyl peptide receptor 1 (FPR1) on SJS/TEN keratinocytes, engaging the RIPK1/RIPK3 necroptosis signalling complex and producing necrotic — rather than purely apoptotic — keratinocyte death. SJS/TEN keratinocytes (and not control or ordinary drug skin reaction keratinocytes) express abundant FPR1, explaining tissue selectivity. Inhibition of necroptosis prevents disease in humanised mouse models, demonstrating that this pathway is causally required for the full-thickness epidermal damage observed clinically.

keratinocyte link

ANXA1 link FPR1 link RIPK1 link RIPK3 link

necroptotic process link necroptotic signaling pathway link

Downstream

Confluent Epidermal Necrosis and Detachment RIPK1/RIPK3-dependent keratinocyte necroptosis is required for the SJS/TEN phenotype in vivo; inhibition of necroptosis prevents disease in humanised mouse models, establishing a direct edge from this node to the final epidermal-necrosis output.

Show evidence (3 references)

PMID:25031270 SUPPORT In Vitro

"Mass spectrometric analysis identified annexin A1 as a key mediator of keratinocyte death; depletion of annexin A1 by a specific antibody diminished supernatant cytotoxicity."

Saito et al. (2014 Sci Transl Med) identified annexin A1 from drug-exposed PBMCs as a key SJS/TEN keratinocyte killer; antibody depletion of annexin A1 abolished cytotoxicity, anchoring annexin A1 as the upstream ligand of this necroptosis pathway.

PMID:25031270 SUPPORT In Vitro

"The necroptosis-mediating complex of RIP1 and RIP3 was indispensable for SJS/TEN supernatant-induced keratinocyte death, and SJS/TEN keratinocytes expressed abundant formyl peptide receptor 1 (FPR1), the receptor for annexin A1, whereas control keratinocytes did not."

Saito et al. (2014) demonstrated that the RIPK1/RIPK3 necroptotic complex is required for SJS/TEN keratinocyte death and that FPR1 is selectively expressed on patient keratinocytes — defining the molecular machinery of this node.

PMID:39238098 SUPPORT Human Clinical

"Annexin A1, released from monocytes, interacts with the formyl peptide receptor 1 to induce necroptosis."

Hasegawa & Abe (2024) — a recent comprehensive review — confirm the annexin A1 → FPR1 → necroptosis axis as an established SJS/TEN pathomechanism, ratifying this node as a current pillar of the pathograph.

Macrophage CXCL10-CXCR3 / TNF Amplification

A distinct amplification mechanism specific to immune checkpoint inhibitor (ICI)-induced SJS/TEN. ICI-activated peripheral T cells trigger monocyte differentiation into macrophages that infiltrate skin lesions and overexpress CXCL10. CXCL10 recruits CXCR3+ cytotoxic T lymphocytes to the epidermis, and TNF signalling drives both the macrophage CXCL10 output and the resulting CTL activation. The pathway is causally inferred from single-cell RNA-seq of 25 ICI-induced SJS/TEN patients across six cohorts and from ex vivo TNF blockade experiments. Clinically, biologic TNF blockade (e.g., infliximab) produces faster recovery than corticosteroids in ICI-induced cases without recurrence on continued ICI therapy, validating this axis as an actionable amplification node.

macrophage link CD8-positive cytotoxic T cell link

TNF link

cytokine-mediated signaling pathway link chemokine-mediated signaling pathway link T cell chemotaxis link

Downstream

Drug-Specific Cytotoxic T Cell Activation Macrophage-derived CXCL10 recruits and locally activates CXCR3+ cytotoxic T lymphocytes within ICI-induced SJS/TEN skin lesions, feeding back into the drug-specific CTL effector node. TNF signalling is the molecular driver of this CTL activation step.

Show evidence (2 references)

PMID:39737932 SUPPORT Human Clinical

"ScRNA expression profiles and ex vivo blocking studies further identify TNF signaling as a pathway responsible for macrophage-derived CXCL10 and CTL activation."

Chen et al. (2024) used scRNA-seq and ex vivo TNF blockade in 25 ICI-induced SJS/TEN patients to establish TNF signalling as the upstream driver of macrophage CXCL10 production and CTL activation in this ICI-specific amplification axis.

PMID:39737932 SUPPORT Human Clinical

"patients treated with biologic TNF blockade showed a significantly rapid recovery and no recurrence of SCAR with continuous ICI therapy."

Chen et al. (2024) provide clinical validation that pharmacological blockade of this TNF-driven amplification axis improves outcomes in ICI-induced SJS/TEN, supporting therapeutic targetability of this node.

Confluent Epidermal Necrosis and Detachment

Convergence node where the parallel effector arms (granulysin, perforin/granzyme, Fas–FasL, RIPK1/RIPK3 necroptosis, IL-15-amplified cytotoxicity) collectively kill keratinocytes across all epidermal layers. The resulting confluent full-thickness epidermal necrosis with subepidermal blister formation and sloughing is the histopathological substrate for the cardinal clinical phenotypes of SJS — skin detachment, mucosal erosions, ocular complications, pain, fluid/electrolyte loss with downstream renal injury, and infection-prone open wound surface (sepsis risk).

keratinocyte link

keratinocyte apoptotic process link necroptotic process link

Show evidence (2 references)

PMID:34577817 SUPPORT Human Clinical

"Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) are rare diseases that are characterized by widespread epidermal necrosis and sloughing of skin."

Frantz et al. (2021) summarise the convergent epidermal necrosis output that defines SJS/TEN clinically and histologically, supporting this node as the final common pathway feeding clinical phenotypes.

PMID:22541332 SUPPORT Human Clinical

"Fas-FasL and perforin/granzyme B have been advocated mediating the epidermal necrosis in SJS/TEN. Our recent study showed that granulysin, a cytotoxic protein produced by CTLs or natural killer (NK) cells, is the key mediator for disseminated keratinocyte death in SJS/TEN."

Chung and Hung (2012) explicitly describe convergence of multiple cytotoxic pathways onto the epidermal necrosis output, supporting the design of this final common pathway node.

✶

Histopathology

2

Full-Thickness Epidermal Necrosis

The hallmark histopathological finding in SJS is confluent full-thickness epidermal necrosis, contrasting with the focal necrosis of erythema multiforme. Necrotic keratinocytes appear as eosinophilic "ghost cells" throughout all epidermal layers, reflecting the massive CTL/NK cell-mediated apoptosis. Subepidermal blister formation with detachment of the entire epidermis from the dermis occurs as necrosis progresses.

Show evidence (2 references)

PMID:29188475 SUPPORT Human Clinical

"The diagnosis of different degrees of epidermal necrolysis is based on the clinical assessment in conjunction with the corresponding histopathology."

Lerch et al. (2018) describe histopathological confirmation as integral to SJS/TEN diagnosis, supporting epidermal necrolysis as the defining histopathological finding.

PMID:22541332 SUPPORT Human Clinical

"granulysin, a cytotoxic protein produced by CTLs or natural killer (NK) cells, is the key mediator for disseminated keratinocyte death in SJS/TEN."

Chung and Hung (2012) confirm that disseminated keratinocyte death by granulysin is the molecular basis for the widespread epidermal necrosis seen histopathologically.

Lymphocytic Interface Dermatitis with Cytotoxic Infiltrate

Biopsy of early SJS lesions shows lymphocytic infiltrate at the dermoepidermal junction with vacuolar degeneration of basal keratinocytes (interface dermatitis pattern) and satellite cell necrosis. Blister cells are predominantly CD8+ CTLs with strong granzyme B immunoreactivity. This pattern distinguishes SJS/TEN from other blistering disorders and from morbilliform drug eruptions.

Show evidence (2 references)

PMID:15536433 SUPPORT In Vitro

"Blister cells showed a strong immunoreactivity for granzyme B, and cytotoxicity was abolished by EGTA, but not by anti-Fas/CD95, suggesting perforin/granzyme-mediated killing."

Nassif et al. (2004) characterized the blister cell infiltrate in TEN/SJS as granzyme B-positive cytotoxic T lymphocytes, directly describing the histopathological cellular composition of the infiltrate.

PMID:19029983 SUPPORT Human Clinical

"blister cells from skin lesions of SJS-TEN primarily consist of cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells, and both blister fluids and cells were cytotoxic."

Chung et al. (2008) confirmed that the cellular infiltrate in SJS-TEN skin lesions consists predominantly of CTLs and NK cells with cytotoxic activity, supporting the lymphocytic interface dermatitis pattern.

⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.

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Phenotypes

10

Cardiovascular 1

Conjunctivitis and Ocular Complications Conjunctivitis (HP:0000509)

Show evidence (2 references)

PMID:29188475 SUPPORT Human Clinical

"In SJS/TEN, the most common complications are ocular, cutaneous, or renal."

Lerch et al. (2018) identify ocular complications as the most common complications of SJS/TEN, supporting conjunctivitis and ocular involvement as a major phenotypic feature.

PMID:37140876 SUPPORT Human Clinical

"SJS/TEN is a serious, rare multi-system, immune-mediated, mucocutaneous disease with a significant mortality rate that can lead to severe ocular surface sequelae and even to bilateral blindness."

Tóth et al. (2023 Ophthalmol Ther) — narrative review focused on the ophthalmic burden of SJS/TEN — confirm severe ocular surface sequelae including bilateral blindness as recognized chronic outcomes that warrant systematic ophthalmic surveillance.

Genitourinary 2

Genital Mucosal Erosions Genital ulcers (HP:0003249)

Show evidence (1 reference)

PMID:29188475 SUPPORT Human Clinical

"SJS/TEN manifest with an "influenza-like" prodromal phase (malaise, fever), followed by painful cutaneous and mucous membrane (ocular, oral, and genital) lesions, and other systemic symptoms."

Lerch et al. (2018) describe genital mucous membrane involvement as part of the characteristic mucocutaneous presentation of SJS/TEN.

Renal Complications FREQUENT Renal insufficiency (HP:0000083)

Show evidence (1 reference)

PMID:29188475 SUPPORT Human Clinical

"In SJS/TEN, the most common complications are ocular, cutaneous, or renal."

Lerch et al. (2018) explicitly identify renal complications among the most common manifestations of SJS/TEN, supporting renal insufficiency as a recognized phenotypic feature requiring monitoring.

Head and Neck 1

Oral Mucosal Erosions Erosion of oral mucosa (HP:0031446)

Show evidence (1 reference)

PMID:29188475 SUPPORT Human Clinical

"SJS/TEN manifest with an "influenza-like" prodromal phase (malaise, fever), followed by painful cutaneous and mucous membrane (ocular, oral, and genital) lesions, and other systemic symptoms."

Lerch et al. (2018) describe oral mucous membrane involvement as a hallmark of SJS/TEN, confirming oral mucosal erosions as a universal clinical feature.

Integument 1

Skin Detachment Skin detachment (HP:0032156)

Show evidence (2 references)

PMID:29188475 SUPPORT Human Clinical

"The difference between SJS, SJS/TEN overlap, and TEN is defined by the degree of skin detachment: SJS is defined as skin involvement of < 10%, TEN is defined as skin involvement of > 30%, and SJS/TEN overlap as 10-30% skin involvement."

Lerch et al. (2018) define SJS by its extent of skin detachment (<10% BSA), directly establishing epidermal detachment as the cardinal diagnostic criterion and phenotypic feature.

PMID:34577817 SUPPORT Human Clinical

"Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) are rare diseases that are characterized by widespread epidermal necrosis and sloughing of skin."

Frantz et al. (2021) characterize SJS/TEN by epidermal necrosis and sloughing, confirming skin detachment as the pathognomonic clinical finding.

Metabolism 2

Fever Fever (HP:0001945)

Show evidence (1 reference)

PMID:29188475 SUPPORT Human Clinical

"SJS/TEN manifest with an "influenza-like" prodromal phase (malaise, fever), followed by painful cutaneous and mucous membrane (ocular, oral, and genital) lesions"

Lerch et al. (2018) explicitly describe fever as part of the influenza-like prodromal phase preceding skin lesions, confirming fever as a consistent early phenotypic feature.

Hepatic Involvement FREQUENT Elevated circulating hepatic transaminase concentration (HP:0002910)

Show evidence (1 reference)

PMID:29188475 SUPPORT Human Clinical

"Pulmonary and hepatic involvement is frequent."

Lerch et al. (2018) explicitly state that hepatic involvement is frequent in SJS/TEN, supporting it as a recognized phenotypic complication.

Respiratory 1

Respiratory Complications Respiratory insufficiency (HP:0002093)

Show evidence (1 reference)

PMID:29188475 SUPPORT Human Clinical

"Pulmonary and hepatic involvement is frequent."

Lerch et al. (2018) note that pulmonary involvement is frequent in SJS/TEN, supporting respiratory complications as a recognized phenotypic feature.

Constitutional 2

Flu-like Prodrome and Malaise VERY_FREQUENT Malaise (HP:0033834)

Show evidence (1 reference)

PMID:29188475 SUPPORT Human Clinical

"SJS/TEN manifest with an "influenza-like" prodromal phase (malaise, fever), followed by painful cutaneous and mucous membrane (ocular, oral, and genital) lesions, and other systemic symptoms."

Lerch et al. (2018) describe the influenza-like prodrome featuring malaise as universal in SJS/TEN, preceding the characteristic skin and mucous membrane lesions.

Skin Pain and Burning VERY_FREQUENT Pain (HP:0012531)

Show evidence (1 reference)

PMID:29188475 SUPPORT Human Clinical

"SJS/TEN manifest with an "influenza-like" prodromal phase (malaise, fever), followed by painful cutaneous and mucous membrane (ocular, oral, and genital) lesions, and other systemic symptoms."

Lerch et al. (2018) describe cutaneous lesions in SJS/TEN as explicitly painful, directly supporting skin pain as a cardinal symptom of the acute disease.

🧬

Genetic Associations

3

HLA-B*15:02 Allele

Show evidence (1 reference)

PMID:29793265 SUPPORT Human Clinical

"In the case of carbamazepine-induced SJS/TEN, the tight association of the HLA-B*1502 allele (sensitivity 100%, specificity 97% and odds ratio 2504) provides a plausible basis for further development of such a test to identify individuals at risk of developing this life-threatening condition."

Hung et al. (2005) established the extraordinary strength of the HLA-B*1502 association with carbamazepine-induced SJS/TEN, providing the evidence basis for pharmacogenomic screening guidelines.

HLA-B*58:01 Allele

Show evidence (1 reference)

PMID:22541332 SUPPORT Human Clinical

"The patho-mechanism involving HLA-restricted presentation of a drug or its metabolites for T-cell activation is supported by the findings of strong genetic associations with HLA alleles (e.g. HLA-B*15:02 and carbamazepine-SJS/TEN, and HLA-B*58:01 and allopurinol-SJS/TEN)."

Chung and Hung (2012) confirm HLA-B*58:01 as a key genetic risk factor for allopurinol-induced SJS/TEN, alongside HLA-B*15:02 for carbamazepine.

HLA-A*31:01 Allele

Show evidence (2 references)

PMID:21428769 SUPPORT Human Clinical

"The presence of the HLA-A*3101 allele was associated with carbamazepine-induced hypersensitivity reactions among subjects of Northern European ancestry."

McCormack et al. (2011 NEJM) established HLA-A*31:01 as a strong, replicated determinant of carbamazepine-induced hypersensitivity (including SJS/TEN) in European-ancestry populations, broadening the HLA risk-allele paradigm.

PMID:21428769 SUPPORT Human Clinical

"The presence of the allele increased the risk from 5.0% to 26.0%, whereas its absence reduced the risk from 5.0% to 3.8%."

McCormack et al. (2011) quantified the absolute risk shift conferred by HLA-A*31:01, supporting clinical pharmacogenomic screening recommendations.

💊

Treatments

7

Immediate Drug Withdrawal

Prompt identification and cessation of the offending drug is the single most critical intervention in SJS management. Earlier withdrawal is associated with improved survival, as each additional day of exposure to the causative drug worsens outcomes.

Mechanism Target:

INHIBITS Drug-HLA Direct Interaction — Removing the causative drug eliminates the molecular trigger for HLA-mediated antigen presentation, terminating new CTL activation at the most upstream pharmacological node of the SJS/TEN pathograph.

Show evidence (1 reference)

PMID:28476287 SUPPORT Human Clinical

"Early drug withdrawal is mandatory in all SCARs."

Duong et al. (2017) state unequivocally that early drug withdrawal is mandatory in SCARs, supporting drug withdrawal as the canonical upstream intervention targeting the drug–HLA interaction node.

Show evidence (1 reference)

PMID:28476287 SUPPORT Human Clinical

"Early drug withdrawal is mandatory in all SCARs."

Duong et al. (2017 Lancet) unequivocally state that early drug withdrawal is mandatory in all severe cutaneous adverse reactions including SJS/TEN, reflecting the clinical consensus view.

Specialized Supportive Care

Action: supportive care MAXO:0000950

Management in burn centers or ICU settings with expertise in wound care, fluid and electrolyte replacement, nutritional support, temperature regulation, pain control, and infection prevention is associated with improved survival. Given the similarity to burn injuries, burn unit care is the cornerstone of management.

Show evidence (1 reference)

PMID:34577817 SUPPORT Human Clinical

"Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) are rare diseases that are characterized by widespread epidermal necrosis and sloughing of skin. They are associated with significant morbidity and mortality, and early diagnosis and treatment is critical in achieving favorable..."

Frantz et al. (2021) emphasize that early diagnosis and treatment — including specialized supportive care — is critical for favorable outcomes in SJS/TEN.

Cyclosporine

Action: cyclosporine immunosuppression Ontology label: pharmacotherapy MAXO:0000058

Cyclosporine A is the most effective immunosuppressive therapy for SJS, halting disease progression by suppressing CTL activity and blocking further keratinocyte killing. Multiple retrospective and prospective studies support its use in SJS, and it is considered first-line immunosuppressive treatment.

Mechanism Target:

INHIBITS Drug-Specific Cytotoxic T Cell Activation — Calcineurin inhibition by cyclosporine A blocks T cell receptor signalling and clonal expansion of drug-specific CD8+ CTLs, halting the upstream effector node of the SJS/TEN pathograph.

Show evidence (1 reference)

PMID:34577817 SUPPORT Human Clinical

"cyclosporine is the most effective therapy for the treatment of SJS"

Frantz et al. (2021) identify cyclosporine as the most effective SJS therapy, consistent with its mechanism of suppressing the drug-specific CTL activation node.

Target Phenotypes: Skin detachment ↗

Show evidence (2 references)

PMID:34577817 SUPPORT Human Clinical

"cyclosporine is the most effective therapy for the treatment of SJS, and a combination of intravenous immunoglobulin (IVIg) and corticosteroids is most effective for SJS/TEN overlap and TEN."

Frantz et al. (2021) identify cyclosporine as the most effective treatment specifically for SJS, distinguishing its role from IVIG+corticosteroids for TEN and SJS/TEN overlap.

PMID:29188475 SUPPORT Human Clinical

"The most frequently used treatments for SJS/TEN are systemic corticosteroids, immunoglobulins, and cyclosporine A."

Lerch et al. (2018) confirm cyclosporine A as one of the most frequently used treatments for SJS/TEN in clinical practice.

Intravenous Immunoglobulin

Action: intravenous immunoglobulin therapy Ontology label: pharmacotherapy MAXO:0000058

IVIG has been used to block Fas–FasL mediated apoptosis and modulate the immune response. Evidence for SJS-specific efficacy is mixed; combined IVIG with corticosteroids appears most effective for SJS/TEN overlap and TEN.

Mechanism Target:

INHIBITS Fas-FasL Keratinocyte Apoptosis — Anti-Fas blocking antibodies present in pooled IVIG are proposed to neutralise keratinocyte Fas engagement by sFasL, attenuating extrinsic-pathway apoptosis of keratinocytes.

Show evidence (1 reference)

PMID:34577817 PARTIAL Human Clinical

"a combination of intravenous immunoglobulin (IVIg) and corticosteroids is most effective for SJS/TEN overlap and TEN."

Frantz et al. (2021) describe IVIG efficacy in SJS/TEN overlap and TEN; the canonical mechanistic proposal is anti-Fas neutralisation of the Fas-FasL keratinocyte apoptosis node, but evidence is indirect — hence PARTIAL.

Target Phenotypes: Skin detachment ↗

Show evidence (1 reference)

PMID:34577817 PARTIAL Human Clinical

"a combination of intravenous immunoglobulin (IVIg) and corticosteroids is most effective for SJS/TEN overlap and TEN. Due to the rare nature of the disease, there is a lack of prospective, randomized controlled trials and conducting these in the future would provide valuable insights into the..."

Frantz et al. (2021) support IVIG use primarily for SJS/TEN overlap and TEN rather than isolated SJS, and acknowledge the lack of RCT-level evidence — hence the PARTIAL support rating.

Systemic Corticosteroids

Action: corticosteroid therapy Ontology label: Systemic Corticosteroid Therapy NCIT:C122080

Systemic corticosteroids (e.g., dexamethasone, methylprednisolone) are among the most frequently used treatments for SJS/TEN despite ongoing controversy about benefit versus risk. They suppress immune activation and CTL-mediated keratinocyte killing but may increase infection risk in patients with open skin wounds. Short-course pulse regimens may reduce harm while capitalizing on anti-inflammatory efficacy.

Mechanism Target:

INHIBITS Drug-Specific Cytotoxic T Cell Activation — Glucocorticoid signalling broadly suppresses T cell activation, cytokine transcription (including IL-15-amplification cytokines), and CTL effector function, dampening upstream drivers of keratinocyte killing.

Show evidence (1 reference)

PMID:29188475 PARTIAL Human Clinical

"The most frequently used treatments for SJS/TEN are systemic corticosteroids, immunoglobulins, and cyclosporine A."

Lerch et al. (2018) confirm corticosteroids as a frequently used SJS/TEN therapy; the proposed mechanistic target is the upstream CTL activation node, though benefit-vs-risk evidence is mixed (PARTIAL).

Target Phenotypes: Skin detachment ↗

Show evidence (1 reference)

PMID:29188475 PARTIAL Human Clinical

"The most frequently used treatments for SJS/TEN are systemic corticosteroids, immunoglobulins, and cyclosporine A."

Lerch et al. (2018) confirm systemic corticosteroids as one of the most frequently used treatments for SJS/TEN in clinical practice. However, evidence of benefit is not definitive, hence PARTIAL support; they are widely used but remain controversial.

Amniotic Membrane Transplantation

Action: amniotic membrane transplantation Ontology label: surgical procedure MAXO:0000004

Timely placement of amniotic membrane (or ProKera devices) on the ocular surface during the acute phase of SJS/TEN suppresses ocular surface inflammation, prevents conjunctival scarring and symblepharon formation, and reduces the risk of chronic ocular surface disease and bilateral blindness — the dominant long-term morbidity of SJS/TEN survivorship. Acute-phase ophthalmic surveillance with prompt amniotic membrane therapy is a cornerstone of SJS/TEN ocular care.

Target Phenotypes: Conjunctivitis ↗ Symblepharon ↗ Corneal scarring ↗

Show evidence (1 reference)

PMID:37140876 SUPPORT Human Clinical

"Early diagnosis, timely amniotic membrane transplantation and aggressive topical management in acute SJS/TEN are necessary to prevent long-term, chronic ocular complications."

Tóth et al. (2023 Ophthalmol Ther) — narrative review of SJS/TEN ocular management — establish timely amniotic membrane transplantation in the acute phase as a key intervention to prevent severe chronic ocular complications.

TNF Inhibitor Therapy

Action: pharmacotherapy MAXO:0000058

Agent: monoclonal antibody ↗

Biologic TNF blockade (e.g., infliximab, etanercept) is an emerging targeted therapy with mechanistic rationale grounded in 2024 single-cell evidence that TNF signalling drives macrophage CXCL10 production and downstream CXCR3+ CTL recruitment in immune checkpoint inhibitor (ICI)–induced SJS/TEN. In the Chen et al. (2024 Nat Commun) ICI-induced SJS/TEN cohort, biologic TNF blockade produced significantly faster recovery than systemic corticosteroids and allowed continuation of ICI therapy without SCAR recurrence. The role of anti-TNF for non-ICI-induced SJS/TEN remains investigational and is being explored in current reviews.

Mechanism Target:

INHIBITS Macrophage CXCL10-CXCR3 / TNF Amplification — Anti-TNF biologic therapy directly inhibits the TNF signalling node that drives macrophage CXCL10 output and CXCR3+ CTL recruitment in ICI-induced SJS/TEN, breaking the amplification loop.

Show evidence (1 reference)

PMID:39737932 SUPPORT Human Clinical

"patients treated with biologic TNF blockade showed a significantly rapid recovery and no recurrence of SCAR with continuous ICI therapy."

Chen et al. (2024) clinically validated that pharmacological TNF blockade hits this amplification node and improves outcomes in ICI-induced SJS/TEN.

Target Phenotypes: Skin detachment ↗

Show evidence (2 references)

PMID:39737932 SUPPORT Human Clinical

"Compared with systemic corticosteroids treatment, ICI-induced SJS/TEN patients treated with biologic TNF blockade showed a significantly rapid recovery and no recurrence of SCAR with continuous ICI therapy."

Chen et al. (2024 Nat Commun) demonstrated superior outcomes for biologic TNF blockade versus systemic corticosteroids in ICI-induced SJS/TEN, establishing anti-TNF as a mechanism-targeted therapy in this setting.

PMID:39238098 PARTIAL Human Clinical

"Recent studies have investigated the potential benefits of tumor necrosis factor-α antagonists."

Hasegawa & Abe (2024) flag TNF-α antagonists as an actively investigated therapeutic option in SJS/TEN beyond the ICI-induced subset; PARTIAL because broader (non-ICI) RCT-level evidence is still limited.

🌍

Environmental Factors

1

High-Risk Drug Exposure

Medications are the predominant trigger. Highest-risk drugs include anti-infective sulfonamides (trimethoprim-sulfamethoxazole; relative risk 172), aromatic anticonvulsants (carbamazepine RR 90, phenytoin RR 53), allopurinol (RR 52), oxicam NSAIDs (RR 72), and nevirapine. Risk is highest within the first 8 weeks of drug exposure for long-term medications.

Show evidence (2 references)

PMID:7477195 SUPPORT Human Clinical

"Among drugs usually used for short periods, the risks were increased for trimethoprim-sulfamethoxazole and other sulfonamide antibiotics (crude relative risk, 172; 95 percent confidence interval, 75 to 396)"

The landmark NEJM case-control study by Roujeau et al. (1995) quantified specific drug relative risks for SJS/TEN, identifying sulfonamide antibiotics as the highest-risk short-term medications.

PMID:29188475 SUPPORT Human Clinical

"Besides conventional drugs, herbal remedies and new biologicals should be considered as causative agents."

Lerch et al. (2018) expand the list of environmental triggers beyond conventional medications to include herbal remedies and biologics.

🔬

Biochemical Markers

5

Elevated Serum Urea (Elevated)

Context: SCORTEN criterion; >10 mmol/L is an independent predictor of mortality

Show evidence (1 reference)

PMID:10951229 SUPPORT Human Clinical

"serum urea above 10 mmol per liter"

Bastuji-Garin et al. (2000) identified elevated serum urea (>10 mmol/L) as one of seven independent risk factors for death in TEN/SJS, constituting a SCORTEN severity-of-illness criterion.

Low Serum Bicarbonate (Decreased)

Context: SCORTEN criterion; <20 mmol/L is an independent predictor of mortality

Show evidence (1 reference)

PMID:10951229 SUPPORT Human Clinical

"bicarbonate below 20 mmol per liter"

Bastuji-Garin et al. (2000) identified bicarbonate below 20 mmol/L as one of seven independent risk factors for death in TEN/SJS within the SCORTEN score.

Elevated Blood Glucose (Elevated)

Context: SCORTEN criterion; >14 mmol/L is an independent predictor of mortality

Show evidence (1 reference)

PMID:10951229 SUPPORT Human Clinical

"serum glucose above 14 mmol per liter"

Bastuji-Garin et al. (2000) identified elevated blood glucose (>14 mmol/L) as one of seven independent risk factors for death in TEN/SJS within the SCORTEN score.

Elevated C-Reactive Protein (Elevated)

Context: Nonspecific acute-phase reactant; reflects systemic inflammatory response

Elevated Soluble FasL (Elevated)

Context: Elevated in SJS and TEN; potential early diagnostic biomarker

Show evidence (1 reference)

PMID:12707034 SUPPORT Human Clinical

"the serum sFasL level may be a good indicator for the early diagnosis of TEN and SJS."

Abe et al. (2003) demonstrated elevated soluble FasL in SJS and TEN patients versus controls, supporting sFasL as a potential biochemical marker for early diagnosis.

{ }

Source YAML

click to show

name: Stevens-Johnson Syndrome
creation_date: "2026-03-19T00:00:00Z"
updated_date: "2026-04-26T00:00:00Z"
description: >
  A severe, life-threatening mucocutaneous drug hypersensitivity reaction characterized
  by extensive epidermal detachment and mucous membrane erosions affecting less than 10%
  of body surface area. SJS is considered part of a spectrum with toxic epidermal
  necrolysis (TEN), with SJS/TEN overlap defined by 10–30% BSA involvement and TEN by
  >30%. Most cases are drug-induced; the pathomechanism centers on drug-specific
  cytotoxic T lymphocytes and NK cells that kill keratinocytes primarily via secretory
  granulysin. Specific HLA alleles (e.g., HLA-B*15:02 for carbamazepine, HLA-B*58:01
  for allopurinol) confer ethnic-specific susceptibility.
category: Complex
synonyms:
- SJS
- erythema multiforme major (historical; now considered a distinct entity)
disease_term:
  preferred_term: Stevens-Johnson syndrome
  term:
    id: MONDO:0018229
    label: Stevens-Johnson syndrome
parents:
- Drug Hypersensitivity Reaction
- Mucocutaneous Disease
has_subtypes:
- name: SJS/TEN Overlap
  description: >
    Intermediate form with 10–30% body surface area epidermal detachment, sharing
    features of both Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis.
  evidence:
  - reference: PMID:29188475
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The difference between SJS, SJS/TEN overlap, and TEN is defined by the degree of skin detachment: SJS is defined as skin involvement of < 10%, TEN is defined as skin involvement of > 30%, and SJS/TEN overlap as 10-30% skin involvement."
    explanation: >
      This comprehensive review defines the SJS/TEN spectrum classification by degree of
      epidermal detachment, supporting the intermediate SJS/TEN overlap subtype category.
- name: Drug-Induced SJS
  description: >
    The predominant form, triggered by medications including anti-infective sulfonamides,
    anticonvulsants (carbamazepine, phenytoin, lamotrigine), allopurinol, oxicam NSAIDs,
    and nevirapine. Risk is greatest within the first two months of drug exposure.
  evidence:
  - reference: PMID:7477195
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Among drugs usually used for months or years, the increased risk was confined largely to the first two months of treatment, when crude relative risks were as follows: carbamazepine, 90 (95 percent confidence interval, 19 to infinity); phenobarbital, 45 (19 to 108); phenytoin, 53 (11 to infinity)"
    explanation: >
      This landmark NEJM case-control study quantified the drug-specific relative risks
      for SJS/TEN, establishing carbamazepine, phenytoin, sulfonamides, and allopurinol
      as the highest-risk medications, and the first two months of exposure as the
      critical risk window.
  - reference: PMID:29188475
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Drugs with a high risk of causing SJS/TEN are anti-infective sulfonamides, anti-epileptic drugs, non-steroidal anti-inflammatory drugs of the oxicam type, allopurinol, nevirapine, and chlormezanone."
    explanation: >
      Lerch et al. (2018) provides a current enumeration of high-risk causative drugs,
      corroborating the drug-induced nature of SJS as the predominant form.
pathophysiology:
- name: HLA-Mediated Genetic Susceptibility
  description: >
    Specific HLA class I alleles are strongly associated with SJS/TEN triggered by
    particular drugs in specific ethnic populations. HLA-B*15:02 confers extremely
    high risk of carbamazepine-induced SJS/TEN in Southeast Asian populations
    (odds ratio 2504); HLA-B*58:01 predisposes to allopurinol-induced SJS/TEN;
    HLA-A*31:01 confers risk of carbamazepine-induced SJS/TEN in Northern European
    populations (OR 25.93). These alleles act as the upstream genetic determinant
    that enables aberrant drug presentation and is the entry point of the SJS/TEN
    causal cascade.
  biological_processes:
  - preferred_term: antigen processing and presentation of peptide antigen via MHC class I
    term:
      id: GO:0002474
      label: antigen processing and presentation of peptide antigen via MHC class I
  genes:
  - preferred_term: HLA-B
    term:
      id: hgnc:4932
      label: HLA-B
  - preferred_term: HLA-A
    term:
      id: hgnc:4931
      label: HLA-A
  downstream:
  - target: Drug-HLA Direct Interaction
    description: >
      Risk HLA alleles physically present the parent drug (or a reactive metabolite)
      in their peptide-binding groove, generating the molecular trigger for CTL
      activation.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:22322005
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "The endogenous peptide-loaded HLA-B∗1502 molecule presented CBZ to CTLs without the involvement of intracellular drug metabolism or antigen processing."
      explanation: >
        Wei and Chung (2012) provided structural/functional evidence that the
        risk allele HLA-B*15:02 directly engages carbamazepine, establishing the
        upstream HLA→drug-presentation edge in the causal graph.
  evidence:
  - reference: PMID:29793265
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In the case of carbamazepine-induced SJS/TEN, the tight association of the HLA-B*1502 allele (sensitivity 100%, specificity 97% and odds ratio 2504) provides a plausible basis for further development of such a test to identify individuals at risk of developing this life-threatening condition."
    explanation: >
      Hung, Chung and Chen (2005) demonstrated that HLA-B*1502 has near-perfect
      sensitivity and specificity for carbamazepine-induced SJS/TEN in Asian
      populations, anchoring the genetic root of the SJS/TEN pathograph.
  - reference: PMID:22541332
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The patho-mechanism involving HLA-restricted presentation of a drug or its metabolites for T-cell activation is supported by the findings of strong genetic associations with HLA alleles (e.g. HLA-B*15:02 and carbamazepine-SJS/TEN, and HLA-B*58:01 and allopurinol-SJS/TEN)."
    explanation: >
      Chung and Hung (2012) review confirms the HLA allele associations for both
      carbamazepine (HLA-B*15:02) and allopurinol (HLA-B*58:01) as genetic
      determinants of SJS/TEN susceptibility.
  - reference: PMID:21428769
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The presence of the HLA-A*3101 allele was associated with carbamazepine-induced hypersensitivity reactions among subjects of Northern European ancestry."
    explanation: >
      McCormack et al. (2011 NEJM) extended the HLA risk-allele model to European
      populations, identifying HLA-A*31:01 as a strong determinant of carbamazepine-
      induced SJS/TEN (OR 25.93) and broadening the genetic-susceptibility node
      beyond Han Chinese HLA-B*15:02.
- name: Drug-HLA Direct Interaction
  description: >
    The causative drug (e.g. carbamazepine, allopurinol metabolite oxypurinol)
    binds non-covalently to the antigen-binding groove of the risk HLA class I
    molecule on antigen-presenting cells and keratinocytes, without requiring
    intracellular processing or covalent haptenation. This "p-i concept"
    (pharmacological interaction with immune receptors) generates a neoantigen-like
    surface that engages drug-specific T cell receptors. Allele-specific drug
    binding explains why a single drug triggers SJS only in carriers of a particular
    HLA allele.
  biological_processes:
  - preferred_term: antigen processing and presentation of peptide antigen via MHC class I
    term:
      id: GO:0002474
      label: antigen processing and presentation of peptide antigen via MHC class I
  downstream:
  - target: Drug-Specific Cytotoxic T Cell Activation
    description: >
      Surface display of the drug–HLA complex licenses recognition by drug-specific
      CD8+ T cell receptors and triggers clonal expansion of effector CTLs.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:22322005
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "The endogenous peptide-loaded HLA-B∗1502 molecule presented CBZ to CTLs without the involvement of intracellular drug metabolism or antigen processing."
      explanation: >
        Direct presentation of carbamazepine on HLA-B*15:02 to CTLs is the molecular
        link from the drug–HLA complex to CTL activation.
  evidence:
  - reference: PMID:22322005
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "The endogenous peptide-loaded HLA-B∗1502 molecule presented CBZ to CTLs without the involvement of intracellular drug metabolism or antigen processing."
    explanation: >
      Wei and Chung (2012) elucidated the molecular mechanism of HLA-B*15:02-mediated
      carbamazepine presentation, showing direct drug interaction with HLA bypassing
      conventional antigen processing — the canonical molecular evidence for the
      p-i model in SJS/TEN.
- name: Drug-Specific Cytotoxic T Cell Activation
  description: >
    Drug antigens (or reactive metabolites) presented via the risk HLA class I
    molecule are recognized by drug-specific CD8+ T cell receptors, initiating a
    type IVc delayed hypersensitivity reaction with robust drug-specific CTL
    expansion directed against keratinocytes. Activated effector T cells traffic
    to skin and mucosa, where they encounter HLA-presenting keratinocytes and
    deploy cytotoxic effector programs (granulysin secretion, Fas-FasL engagement,
    perforin/granzyme delivery, and pro-inflammatory cytokine release).
  cell_types:
  - preferred_term: CD8-positive cytotoxic T cell
    term:
      id: CL:0000794
      label: CD8-positive, alpha-beta cytotoxic T cell
  biological_processes:
  - preferred_term: T cell mediated cytotoxicity
    term:
      id: GO:0001913
      label: T cell mediated cytotoxicity
  - preferred_term: antigen processing and presentation
    term:
      id: GO:0019882
      label: antigen processing and presentation
  downstream:
  - target: Granulysin-Mediated Keratinocyte Apoptosis
    description: >
      Activated drug-specific CTLs and their NK-cell partners secrete granulysin
      into the dermoepidermal junction, the dominant effector molecule causing
      disseminated keratinocyte death.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:19029983
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "blister cells from skin lesions of SJS-TEN primarily consist of cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells, and both blister fluids and cells were cytotoxic. Gene expression profiling identified granulysin as the most highly expressed cytotoxic molecule"
      explanation: >
        Chung et al. (2008) localised granulysin expression to the CTL/NK blister
        infiltrate, establishing the direct edge from CTL activation to granulysin-
        mediated keratinocyte killing.
  - target: Perforin/Granzyme B-Mediated Cytotoxicity
    description: >
      Drug-specific CTLs release perforin/granzyme B into the immunological synapse
      with keratinocytes, an MHC class I-restricted contact-dependent killing
      modality that operates alongside granulysin.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:15536433
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "These results strongly suggest that drug-specific, MHC class I-restricted, perforin/granzyme-mediated cytotoxicity probably has a primary role in TEN."
      explanation: >
        Nassif et al. (2004) directly tied drug-specific CTL activity to perforin/
        granzyme-mediated keratinocyte killing in TEN/SJS.
  - target: Fas-FasL Keratinocyte Apoptosis
    description: >
      Activated PBMCs (including drug-specific CTLs) shed soluble FasL that engages
      keratinocyte Fas and triggers extrinsic-pathway apoptosis as a parallel
      effector arm.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:12707034
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "sFasL secreted by PBMCs, not keratinocytes, plays a crucial role in the apoptosis and pathomechanism of TEN and SJS"
      explanation: >
        Abe et al. (2003) provide the direct edge from PBMC/CTL activation to
        Fas-FasL-mediated keratinocyte apoptosis.
  - target: IL-15 Cytokine Amplification
    description: >
      Activated CTLs and the inflammatory milieu produce IL-15, which feeds back
      to enhance NK and CTL cytotoxic capacity and correlates with SJS/TEN
      severity and mortality.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:28011147
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "IL-15 was shown to enhance cytotoxicity of cultured natural killer cells and blister cells from patients with TEN."
      explanation: >
        Su et al. (2017) established the direct functional edge from IL-15
        production to amplified CTL/NK cytotoxicity in SJS/TEN.
  - target: Lipocalin-2 / NETosis Innate Amplification
    description: >
      Skin-infiltrating CD8+ T cells release lipocalin-2 in a drug-specific manner,
      triggering neutrophil extracellular trap (NET) formation in early lesional
      skin and bridging adaptive activation to an innate amplification loop.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:34193610
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Skin-infiltrating CD8+ T cells produced lipocalin-2 in a drug-specific manner, which triggered the formation of neutrophil extracellular traps (NETs) in early lesional skin."
      explanation: >
        Kinoshita et al. (2021) documented the lipocalin-2-mediated edge from
        drug-specific CD8+ T cell activation to neutrophil-driven amplification.
  evidence:
  - reference: PMID:15536433
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Blister cells also killed IFN-gamma-activated autologous keratinocytes in the presence of drug in the 2 patients tested. Blister cells showed a strong immunoreactivity for granzyme B, and cytotoxicity was abolished by EGTA, but not by anti-Fas/CD95, suggesting perforin/granzyme-mediated killing."
    explanation: >
      Nassif et al. (2004) directly demonstrated that drug-specific CD8+ CTLs are the
      effector cells in TEN/SJS, killing autologous keratinocytes in a drug-dependent
      manner via perforin/granzyme pathways.
  - reference: PMID:22322005
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "The endogenous peptide-loaded HLA-B∗1502 molecule presented CBZ to CTLs without the involvement of intracellular drug metabolism or antigen processing."
    explanation: >
      Wei and Chung (2012) elucidated the molecular mechanism of HLA-B*15:02-mediated
      carbamazepine presentation, showing direct drug interaction with HLA bypassing
      conventional antigen processing — explaining why this reaction affects genetically
      susceptible individuals independent of drug metabolism.
  - reference: PMID:39379371
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) is a rare but life-threatening cutaneous drug reaction mediated by human leukocyte antigen (HLA) class I-restricted CD8+ T cells."
    explanation: >
      Gibson et al. (2024 Nat Commun) — multi-omic single-cell sequencing of
      109,888 cells from 15 SJS/TEN patients — provide contemporary
      transcriptomic confirmation that HLA class I-restricted CD8+ T cells
      drive SJS/TEN, anchoring this node in current single-cell evidence.
  - reference: PMID:39379371
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Keratinocytes express markers indicating HLA class I-restricted antigen presentation and appear to trigger the proliferation of and killing by cytotoxic CD8+ tissue-resident T cells that express granulysin, granzyme B, perforin, LAG3, CD27, and LINC01871"
    explanation: >
      Gibson et al. (2024) directly identified the cytotoxic effector phenotype
      (granulysin/granzyme B/perforin) of tissue-resident CD8+ T cells driving
      SJS/TEN keratinocyte killing, validating the downstream effector arms in
      a contemporary single-cell dataset.
- name: Granulysin-Mediated Keratinocyte Apoptosis
  description: >
    Activated CD8+ CTLs and NK cells release granulysin, a 15-kDa secretory cytotoxic
    protein, which is the dominant effector molecule causing widespread keratinocyte
    death in SJS/TEN. Granulysin concentrations in blister fluid exceed perforin,
    granzyme B, and soluble FasL by two to four orders of magnitude, making it the
    single most important mediator of disseminated keratinocyte death.
  cell_types:
  - preferred_term: keratinocyte
    term:
      id: CL:0000312
      label: keratinocyte
  - preferred_term: natural killer cell
    term:
      id: CL:0000623
      label: natural killer cell
  biological_processes:
  - preferred_term: keratinocyte apoptotic process
    term:
      id: GO:0097283
      label: keratinocyte apoptotic process
  - preferred_term: T cell mediated cytotoxicity
    term:
      id: GO:0001913
      label: T cell mediated cytotoxicity
  genes:
  - preferred_term: GNLY
    term:
      id: hgnc:4414
      label: GNLY
  downstream:
  - target: Confluent Epidermal Necrosis and Detachment
    description: >
      Granulysin-induced keratinocyte death across the basal layer collapses
      epidermal-dermal adhesion, producing the confluent full-thickness necrosis
      and skin detachment that define SJS.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:19029983
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Granulysin concentrations in the blister fluids were two to four orders of magnitude higher than perforin, granzyme B or soluble Fas ligand concentrations, and depleting granulysin reduced the cytotoxicity."
      explanation: >
        Chung et al. (2008) showed granulysin is the dominant mediator whose
        depletion blunts keratinocyte killing — directly linking this effector
        node to the downstream epidermal-necrosis output.
  evidence:
  - reference: PMID:19029983
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Granulysin concentrations in the blister fluids were two to four orders of magnitude higher than perforin, granzyme B or soluble Fas ligand concentrations, and depleting granulysin reduced the cytotoxicity."
    explanation: >
      Chung et al. (2008) demonstrated that granulysin is the dominant cytotoxic
      mediator in SJS/TEN blister fluid, far exceeding other cytotoxic molecules,
      and that its depletion reduces cytotoxicity — directly establishing it as the
      key effector molecule.
  - reference: PMID:19029983
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "blister cells from skin lesions of SJS-TEN primarily consist of cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells, and both blister fluids and cells were cytotoxic. Gene expression profiling identified granulysin as the most highly expressed cytotoxic molecule"
    explanation: >
      Chung et al. (2008) showed that CTLs and NK cells are the dominant blister cells
      and granulysin is the most highly expressed cytotoxic molecule, identifying the
      cellular and molecular effectors.
- name: Fas-FasL Keratinocyte Apoptosis
  description: >
    Soluble FasL (sFasL) secreted by peripheral blood mononuclear cells (PBMCs),
    not by keratinocytes themselves, binds Fas (CD95) on keratinocytes and triggers
    apoptosis via the extrinsic caspase pathway. Elevated serum sFasL levels are
    detected in both SJS and TEN patients compared to controls, and sFasL may
    serve as an early diagnostic biomarker. This pathway acts alongside granulysin
    as a secondary mechanism of keratinocyte killing.
  cell_types:
  - preferred_term: keratinocyte
    term:
      id: CL:0000312
      label: keratinocyte
  biological_processes:
  - preferred_term: keratinocyte apoptotic process
    term:
      id: GO:0097283
      label: keratinocyte apoptotic process
  - preferred_term: extrinsic apoptotic signaling pathway via death domain receptors
    term:
      id: GO:0008625
      label: extrinsic apoptotic signaling pathway via death domain receptors
  genes:
  - preferred_term: FAS
    term:
      id: hgnc:11920
      label: FAS
  - preferred_term: FASLG
    term:
      id: hgnc:11936
      label: FASLG
  downstream:
  - target: Confluent Epidermal Necrosis and Detachment
    description: >
      Fas–FasL extrinsic apoptotic signalling adds a parallel apoptotic load to
      keratinocytes, contributing to the collapse of the epidermis and skin
      detachment phenotype.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:12707034
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "sFasL secreted by PBMCs, not keratinocytes, plays a crucial role in the apoptosis and pathomechanism of TEN and SJS"
      explanation: >
        Abe et al. (2003) directly link PBMC-derived sFasL to keratinocyte apoptosis
        in SJS/TEN, supporting the edge from this effector node to confluent
        epidermal necrosis.
  evidence:
  - reference: PMID:12707034
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Taken together, these results indicate that sFasL secreted by PBMCs, not keratinocytes, plays a crucial role in the apoptosis and pathomechanism of TEN and SJS, and that the serum sFasL level may be a good indicator for the early diagnosis of TEN and SJS."
    explanation: >
      Abe et al. (2003) demonstrated that soluble FasL secreted by PBMCs (not keratinocytes)
      drives keratinocyte apoptosis, with high sFasL levels in SJS and TEN patients versus
      controls — establishing Fas–FasL as an independent apoptotic pathway from granulysin.
- name: Perforin/Granzyme B-Mediated Cytotoxicity
  description: >
    Alongside granulysin, drug-specific CD8+ CTLs kill keratinocytes via the
    perforin/granzyme B pathway. Blister fluid lymphocytes display cytotoxic phenotype
    (CD8+HLA-DR+CLA+CD56+) and kill drug-sensitized keratinocytes; granzyme B
    immunoreactivity is intense in blister cells, and cytotoxicity is abolished by EGTA
    (a perforin inhibitor) but not by anti-Fas, demonstrating perforin/granzyme as an
    independent killing modality distinct from Fas–FasL.
  cell_types:
  - preferred_term: CD8-positive cytotoxic T cell
    term:
      id: CL:0000794
      label: CD8-positive, alpha-beta cytotoxic T cell
  biological_processes:
  - preferred_term: T cell mediated cytotoxicity
    term:
      id: GO:0001913
      label: T cell mediated cytotoxicity
  - preferred_term: keratinocyte apoptotic process
    term:
      id: GO:0097283
      label: keratinocyte apoptotic process
  genes:
  - preferred_term: PRF1
    term:
      id: hgnc:9360
      label: PRF1
  - preferred_term: GZMB
    term:
      id: hgnc:4709
      label: GZMB
  downstream:
  - target: Confluent Epidermal Necrosis and Detachment
    description: >
      Perforin pore formation followed by granzyme B delivery initiates intrinsic
      apoptosis in keratinocytes contacting drug-specific CTLs, contributing
      contact-dependent killing to the final epidermal necrosis output.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:15536433
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "These results strongly suggest that drug-specific, MHC class I-restricted, perforin/granzyme-mediated cytotoxicity probably has a primary role in TEN."
      explanation: >
        Nassif et al. (2004) directly link perforin/granzyme cytotoxicity to
        keratinocyte killing in SJS/TEN — supporting the edge from this effector
        node to confluent epidermal necrosis.
  evidence:
  - reference: PMID:15536433
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "These results strongly suggest that drug-specific, MHC class I-restricted, perforin/granzyme-mediated cytotoxicity probably has a primary role in TEN."
    explanation: >
      Nassif et al. (2004) demonstrated that drug-specific perforin/granzyme B-mediated
      cytotoxicity is an independent killing modality in SJS/TEN, complementing
      granulysin as an effector mechanism.
  - reference: PMID:22541332
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Fas-FasL and perforin/granzyme B have been advocated mediating the epidermal necrosis in SJS/TEN. Our recent study showed that granulysin, a cytotoxic protein produced by CTLs or natural killer (NK) cells, is the key mediator for disseminated keratinocyte death in SJS/TEN."
    explanation: >
      Chung and Hung (2012) describe the hierarchy of cytotoxic mechanisms in SJS/TEN,
      placing perforin/granzyme B alongside granulysin as an effector of epidermal necrosis.
- name: IL-15 Cytokine Amplification
  description: >
    Serum interleukin-15 is markedly elevated in SJS/TEN and correlates with both
    disease severity (SCORTEN) and mortality. IL-15 acts as an amplifier in the
    cytotoxic loop: it potentiates the killing capacity of NK cells and blister-
    derived T cells, increasing the cytotoxic output of upstream CTL/NK effectors
    against keratinocytes. IL-15 thus links T-cell activation to enhanced
    granulysin/perforin-mediated keratinocyte killing and provides a candidate
    therapeutic target.
  cell_types:
  - preferred_term: natural killer cell
    term:
      id: CL:0000623
      label: natural killer cell
  - preferred_term: CD8-positive cytotoxic T cell
    term:
      id: CL:0000794
      label: CD8-positive, alpha-beta cytotoxic T cell
  biological_processes:
  - preferred_term: cytokine-mediated signaling pathway
    term:
      id: GO:0019221
      label: cytokine-mediated signaling pathway
  - preferred_term: natural killer cell mediated cytotoxicity
    term:
      id: GO:0042267
      label: natural killer cell mediated cytotoxicity
  genes:
  - preferred_term: IL15
    term:
      id: hgnc:5977
      label: IL15
  downstream:
  - target: Granulysin-Mediated Keratinocyte Apoptosis
    description: >
      IL-15 enhances NK and CTL cytotoxic capacity, increasing release of granulysin
      and other cytolytic granules into lesional skin and amplifying disseminated
      keratinocyte killing.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:28011147
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "IL-15 was shown to enhance cytotoxicity of cultured natural killer cells and blister cells from patients with TEN."
      explanation: >
        Su et al. (2017) experimentally demonstrated IL-15 enhancement of NK and
        TEN blister-cell cytotoxicity, supporting the amplification edge to
        granulysin-mediated keratinocyte apoptosis.
  - target: Perforin/Granzyme B-Mediated Cytotoxicity
    description: >
      IL-15 sensitises CTLs and NK cells, raising perforin/granzyme delivery into
      keratinocyte synapses.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - increased CTL/NK survival and granule loading
    evidence:
    - reference: PMID:28011147
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "IL-15 was shown to enhance cytotoxicity of cultured natural killer cells and blister cells from patients with TEN."
      explanation: >
        Su et al. (2017) showed IL-15 enhances cytotoxic killing capacity broadly,
        supporting an amplification edge into the perforin/granzyme effector arm.
  evidence:
  - reference: PMID:28011147
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the levels of IL-15 (r = 0.401; P < 0.001) and granulysin (r = 0.223; P = 0.026) were significantly correlated with the disease severity in 112 samples after excluding patients with insufficient data to calculate the score of TEN."
    explanation: >
      Su et al. (2017 J Invest Dermatol) showed that IL-15 levels correlate with
      SJS/TEN severity (SCORTEN) and mortality, identifying IL-15 as an amplifier
      cytokine and prognostic biomarker.
  - reference: PMID:28011147
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "IL-15 was also associated with mortality (P = 0.002; odds ratio, 1.09; 95% confidence interval, 1.03-1.14; P = 0.001; adjusted odds ratio, 1.10; 95% confidence interval, 1.04-1.16)."
    explanation: >
      Su et al. (2017) quantified the mortality association of IL-15 in SJS/TEN,
      anchoring it as a clinically relevant amplification node.
- name: Lipocalin-2 / NETosis Innate Amplification
  description: >
    Drug-specific CD8+ T cells in early lesional skin secrete lipocalin-2, which
    triggers neutrophil extracellular trap (NET) formation by infiltrating
    neutrophils. Neutrophils undergoing NETosis release the antimicrobial peptide
    LL-37, which induces formyl peptide receptor 1 (FPR1) expression on
    keratinocytes. FPR1 expression renders keratinocytes susceptible to
    necroptosis, creating a self-amplifying loop because necroptotic keratinocytes
    in turn release LL-37 and propagate FPR1 induction in neighbouring cells. This
    NETs–FPR1–necroptosis axis is specific to SJS/TEN and not seen in milder
    cutaneous adverse drug reactions.
  cell_types:
  - preferred_term: neutrophil
    term:
      id: CL:0000775
      label: neutrophil
  - preferred_term: keratinocyte
    term:
      id: CL:0000312
      label: keratinocyte
  biological_processes:
  - preferred_term: neutrophil extracellular trap formation
    term:
      id: GO:0140645
      label: neutrophil extracellular trap formation
  downstream:
  - target: Annexin A1-FPR1 Keratinocyte Necroptosis
    description: >
      LL-37 released during NETosis upregulates FPR1 on keratinocytes, priming them
      for annexin A1-mediated necroptosis and amplifying epidermal cell death.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:34193610
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Neutrophils undergoing NETosis released LL-37, an antimicrobial peptide, which induced formyl peptide receptor 1 (FPR1) expression by keratinocytes."
      explanation: >
        Kinoshita et al. (2021) directly showed NETs-derived LL-37 induces FPR1 on
        keratinocytes, the molecular link to FPR1-mediated necroptosis.
  evidence:
  - reference: PMID:34193610
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We describe a mechanism by which neutrophils triggered inflammation during early phases of SJS/TEN."
    explanation: >
      Kinoshita et al. (2021 Sci Transl Med) defined neutrophils and NETosis as
      innate-immune amplifiers in early SJS/TEN lesions, linking adaptive CTL
      activation to keratinocyte necroptosis.
  - reference: PMID:34193610
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "FPR1 expression caused keratinocytes to be vulnerable to necroptosis that caused further release of LL-37 by necroptotic keratinocytes and induced FPR1 expression on surrounding keratinocytes, which likely amplified the necroptotic response."
    explanation: >
      Kinoshita et al. (2021) describe the self-amplifying necroptosis loop in
      which dying keratinocytes propagate FPR1 induction in neighbours, supporting
      the spreading-necrosis output of SJS/TEN.
- name: Annexin A1-FPR1 Keratinocyte Necroptosis
  description: >
    Annexin A1 released by drug-exposed PBMCs binds formyl peptide receptor 1
    (FPR1) on SJS/TEN keratinocytes, engaging the RIPK1/RIPK3 necroptosis
    signalling complex and producing necrotic — rather than purely apoptotic —
    keratinocyte death. SJS/TEN keratinocytes (and not control or ordinary drug
    skin reaction keratinocytes) express abundant FPR1, explaining tissue
    selectivity. Inhibition of necroptosis prevents disease in humanised mouse
    models, demonstrating that this pathway is causally required for the
    full-thickness epidermal damage observed clinically.
  cell_types:
  - preferred_term: keratinocyte
    term:
      id: CL:0000312
      label: keratinocyte
  biological_processes:
  - preferred_term: necroptotic process
    term:
      id: GO:0070266
      label: necroptotic process
  - preferred_term: necroptotic signaling pathway
    term:
      id: GO:0097527
      label: necroptotic signaling pathway
  genes:
  - preferred_term: ANXA1
    term:
      id: hgnc:533
      label: ANXA1
  - preferred_term: FPR1
    term:
      id: hgnc:3826
      label: FPR1
  - preferred_term: RIPK1
    term:
      id: hgnc:10019
      label: RIPK1
  - preferred_term: RIPK3
    term:
      id: hgnc:10021
      label: RIPK3
  downstream:
  - target: Confluent Epidermal Necrosis and Detachment
    description: >
      RIPK1/RIPK3-dependent keratinocyte necroptosis is required for the SJS/TEN
      phenotype in vivo; inhibition of necroptosis prevents disease in humanised
      mouse models, establishing a direct edge from this node to the final
      epidermal-necrosis output.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:25031270
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Inhibition of necroptosis completely prevented SJS/TEN-like responses in a mouse model of SJS/TEN."
      explanation: >
        Saito et al. (2014) demonstrated that necroptosis is causally required
        for SJS/TEN-like skin damage in vivo, supporting the necroptosis →
        epidermal-necrosis edge.
  evidence:
  - reference: PMID:25031270
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Mass spectrometric analysis identified annexin A1 as a key mediator of keratinocyte death; depletion of annexin A1 by a specific antibody diminished supernatant cytotoxicity."
    explanation: >
      Saito et al. (2014 Sci Transl Med) identified annexin A1 from drug-exposed
      PBMCs as a key SJS/TEN keratinocyte killer; antibody depletion of annexin A1
      abolished cytotoxicity, anchoring annexin A1 as the upstream ligand of this
      necroptosis pathway.
  - reference: PMID:25031270
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "The necroptosis-mediating complex of RIP1 and RIP3 was indispensable for SJS/TEN supernatant-induced keratinocyte death, and SJS/TEN keratinocytes expressed abundant formyl peptide receptor 1 (FPR1), the receptor for annexin A1, whereas control keratinocytes did not."
    explanation: >
      Saito et al. (2014) demonstrated that the RIPK1/RIPK3 necroptotic complex is
      required for SJS/TEN keratinocyte death and that FPR1 is selectively
      expressed on patient keratinocytes — defining the molecular machinery of
      this node.
  - reference: PMID:39238098
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Annexin A1, released from monocytes, interacts with the formyl peptide receptor 1 to induce necroptosis."
    explanation: >
      Hasegawa & Abe (2024) — a recent comprehensive review — confirm the
      annexin A1 → FPR1 → necroptosis axis as an established SJS/TEN
      pathomechanism, ratifying this node as a current pillar of the
      pathograph.
- name: Macrophage CXCL10-CXCR3 / TNF Amplification
  description: >
    A distinct amplification mechanism specific to immune checkpoint inhibitor
    (ICI)-induced SJS/TEN. ICI-activated peripheral T cells trigger monocyte
    differentiation into macrophages that infiltrate skin lesions and
    overexpress CXCL10. CXCL10 recruits CXCR3+ cytotoxic T lymphocytes to the
    epidermis, and TNF signalling drives both the macrophage CXCL10 output and
    the resulting CTL activation. The pathway is causally inferred from
    single-cell RNA-seq of 25 ICI-induced SJS/TEN patients across six cohorts
    and from ex vivo TNF blockade experiments. Clinically, biologic TNF blockade
    (e.g., infliximab) produces faster recovery than corticosteroids in
    ICI-induced cases without recurrence on continued ICI therapy, validating
    this axis as an actionable amplification node.
  cell_types:
  - preferred_term: macrophage
    term:
      id: CL:0000235
      label: macrophage
  - preferred_term: CD8-positive cytotoxic T cell
    term:
      id: CL:0000794
      label: CD8-positive, alpha-beta cytotoxic T cell
  biological_processes:
  - preferred_term: cytokine-mediated signaling pathway
    term:
      id: GO:0019221
      label: cytokine-mediated signaling pathway
  - preferred_term: chemokine-mediated signaling pathway
    term:
      id: GO:0070098
      label: chemokine-mediated signaling pathway
  - preferred_term: T cell chemotaxis
    term:
      id: GO:0010818
      label: T cell chemotaxis
  genes:
  - preferred_term: TNF
    term:
      id: hgnc:11892
      label: TNF
  downstream:
  - target: Drug-Specific Cytotoxic T Cell Activation
    description: >
      Macrophage-derived CXCL10 recruits and locally activates CXCR3+ cytotoxic
      T lymphocytes within ICI-induced SJS/TEN skin lesions, feeding back into
      the drug-specific CTL effector node. TNF signalling is the molecular
      driver of this CTL activation step.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:39737932
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "shows overexpression of macrophage-derived CXCL10 that recruits CXCR3+ cytotoxic T lymphocytes (CTL) in blister cells from ICI-SJS/TEN skin lesions."
      explanation: >
        Chen et al. (2024 Nat Commun) directly showed CXCL10/CXCR3-mediated
        recruitment of cytotoxic T cells in ICI-induced SJS/TEN, supporting
        this amplification edge into the CTL activation node.
  evidence:
  - reference: PMID:39737932
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ScRNA expression profiles and ex vivo blocking studies further identify TNF signaling as a pathway responsible for macrophage-derived CXCL10 and CTL activation."
    explanation: >
      Chen et al. (2024) used scRNA-seq and ex vivo TNF blockade in 25
      ICI-induced SJS/TEN patients to establish TNF signalling as the upstream
      driver of macrophage CXCL10 production and CTL activation in this
      ICI-specific amplification axis.
  - reference: PMID:39737932
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "patients treated with biologic TNF blockade showed a significantly rapid recovery and no recurrence of SCAR with continuous ICI therapy."
    explanation: >
      Chen et al. (2024) provide clinical validation that pharmacological
      blockade of this TNF-driven amplification axis improves outcomes in
      ICI-induced SJS/TEN, supporting therapeutic targetability of this node.
- name: Confluent Epidermal Necrosis and Detachment
  description: >
    Convergence node where the parallel effector arms (granulysin, perforin/granzyme,
    Fas–FasL, RIPK1/RIPK3 necroptosis, IL-15-amplified cytotoxicity) collectively
    kill keratinocytes across all epidermal layers. The resulting confluent
    full-thickness epidermal necrosis with subepidermal blister formation and
    sloughing is the histopathological substrate for the cardinal clinical
    phenotypes of SJS — skin detachment, mucosal erosions, ocular complications,
    pain, fluid/electrolyte loss with downstream renal injury, and infection-prone
    open wound surface (sepsis risk).
  cell_types:
  - preferred_term: keratinocyte
    term:
      id: CL:0000312
      label: keratinocyte
  biological_processes:
  - preferred_term: keratinocyte apoptotic process
    term:
      id: GO:0097283
      label: keratinocyte apoptotic process
  - preferred_term: necroptotic process
    term:
      id: GO:0070266
      label: necroptotic process
  evidence:
  - reference: PMID:34577817
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) are rare diseases that are characterized by widespread epidermal necrosis and sloughing of skin."
    explanation: >
      Frantz et al. (2021) summarise the convergent epidermal necrosis output that
      defines SJS/TEN clinically and histologically, supporting this node as the
      final common pathway feeding clinical phenotypes.
  - reference: PMID:22541332
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Fas-FasL and perforin/granzyme B have been advocated mediating the epidermal necrosis in SJS/TEN. Our recent study showed that granulysin, a cytotoxic protein produced by CTLs or natural killer (NK) cells, is the key mediator for disseminated keratinocyte death in SJS/TEN."
    explanation: >
      Chung and Hung (2012) explicitly describe convergence of multiple cytotoxic
      pathways onto the epidermal necrosis output, supporting the design of this
      final common pathway node.
phenotypes:
- name: Skin Detachment
  description: >
    Epidermal detachment involving less than 10% of the body surface area is the
    defining feature of SJS. Detachment presents as blistering and erosions; the
    Nikolsky sign (skin sloughing upon lateral pressure) is characteristically positive.
    Skin detachment is preceded by a prodromal period of fever and influenza-like
    symptoms.
  phenotype_term:
    preferred_term: Skin detachment
    term:
      id: HP:0032156
      label: Skin detachment
  evidence:
  - reference: PMID:29188475
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The difference between SJS, SJS/TEN overlap, and TEN is defined by the degree of skin detachment: SJS is defined as skin involvement of < 10%, TEN is defined as skin involvement of > 30%, and SJS/TEN overlap as 10-30% skin involvement."
    explanation: >
      Lerch et al. (2018) define SJS by its extent of skin detachment (<10% BSA),
      directly establishing epidermal detachment as the cardinal diagnostic criterion
      and phenotypic feature.
  - reference: PMID:34577817
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) are rare diseases that are characterized by widespread epidermal necrosis and sloughing of skin."
    explanation: >
      Frantz et al. (2021) characterize SJS/TEN by epidermal necrosis and sloughing,
      confirming skin detachment as the pathognomonic clinical finding.
- name: Oral Mucosal Erosions
  description: >
    Painful erosions of the oral mucosa occur in virtually all patients, often
    preceding or coinciding with cutaneous manifestations. Oral lesions cause
    odynophagia and difficulty maintaining nutrition.
  phenotype_term:
    preferred_term: Erosion of oral mucosa
    term:
      id: HP:0031446
      label: Erosion of oral mucosa
  evidence:
  - reference: PMID:29188475
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "SJS/TEN manifest with an \"influenza-like\" prodromal phase (malaise, fever), followed by painful cutaneous and mucous membrane (ocular, oral, and genital) lesions, and other systemic symptoms."
    explanation: >
      Lerch et al. (2018) describe oral mucous membrane involvement as a hallmark
      of SJS/TEN, confirming oral mucosal erosions as a universal clinical feature.
- name: Genital Mucosal Erosions
  description: >
    Painful erosions of genital mucous membranes occur frequently alongside oral
    and ocular involvement. Genital lesions can cause dysuria and significant
    discomfort, and may lead to scarring complications.
  phenotype_term:
    preferred_term: Genital mucosal erosion
    term:
      id: HP:0003249
      label: Genital ulcers
  evidence:
  - reference: PMID:29188475
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "SJS/TEN manifest with an \"influenza-like\" prodromal phase (malaise, fever), followed by painful cutaneous and mucous membrane (ocular, oral, and genital) lesions, and other systemic symptoms."
    explanation: >
      Lerch et al. (2018) describe genital mucous membrane involvement as part of
      the characteristic mucocutaneous presentation of SJS/TEN.
- name: Fever
  description: >
    High fever (commonly >38.5°C) is a prominent systemic feature, typically appearing
    in the prodromal period 1–3 days before cutaneous manifestations and reflecting
    systemic immune activation.
  phenotype_term:
    preferred_term: Fever
    term:
      id: HP:0001945
      label: Fever
  evidence:
  - reference: PMID:29188475
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "SJS/TEN manifest with an \"influenza-like\" prodromal phase (malaise, fever), followed by painful cutaneous and mucous membrane (ocular, oral, and genital) lesions"
    explanation: >
      Lerch et al. (2018) explicitly describe fever as part of the influenza-like
      prodromal phase preceding skin lesions, confirming fever as a consistent
      early phenotypic feature.
- name: Conjunctivitis and Ocular Complications
  description: >
    Conjunctivitis, corneal ulceration, and symblepharon formation occur in up to 80%
    of patients. Acute ocular inflammation can progress to chronic sequelae including
    conjunctival scarring, trichiasis, and vision loss, representing major long-term
    morbidity. Chronic ocular surface disease — including limbal stem cell
    deficiency, corneal scarring, and bilateral blindness — is a leading
    long-term consequence of SJS/TEN survivorship.
  phenotype_term:
    preferred_term: Conjunctivitis
    term:
      id: HP:0000509
      label: Conjunctivitis
  evidence:
  - reference: PMID:29188475
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In SJS/TEN, the most common complications are ocular, cutaneous, or renal."
    explanation: >
      Lerch et al. (2018) identify ocular complications as the most common complications
      of SJS/TEN, supporting conjunctivitis and ocular involvement as a major
      phenotypic feature.
  - reference: PMID:37140876
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "SJS/TEN is a serious, rare multi-system, immune-mediated, mucocutaneous disease with a significant mortality rate that can lead to severe ocular surface sequelae and even to bilateral blindness."
    explanation: >
      Tóth et al. (2023 Ophthalmol Ther) — narrative review focused on the
      ophthalmic burden of SJS/TEN — confirm severe ocular surface sequelae
      including bilateral blindness as recognized chronic outcomes that
      warrant systematic ophthalmic surveillance.
- name: Respiratory Complications
  description: >
    Bronchial epithelial involvement with shedding of bronchial mucosa can cause
    respiratory distress, pneumonia, and respiratory failure. Pulmonary involvement
    is a significant contributor to morbidity and mortality in SJS/TEN.
  phenotype_term:
    preferred_term: Respiratory insufficiency
    term:
      id: HP:0002093
      label: Respiratory insufficiency
  evidence:
  - reference: PMID:29188475
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Pulmonary and hepatic involvement is frequent."
    explanation: >
      Lerch et al. (2018) note that pulmonary involvement is frequent in SJS/TEN,
      supporting respiratory complications as a recognized phenotypic feature.
- name: Flu-like Prodrome and Malaise
  category: Constitutional
  frequency: VERY_FREQUENT
  description: >
    A 1–3-day prodromal period of malaise, fatigue, sore throat, and general
    "influenza-like" symptoms precedes the onset of skin and mucous membrane
    lesions. This early systemic syndrome reflects the initial immune activation
    and is clinically important for early recognition.
  phenotype_term:
    preferred_term: Malaise
    term:
      id: HP:0033834
      label: Malaise
  evidence:
  - reference: PMID:29188475
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "SJS/TEN manifest with an \"influenza-like\" prodromal phase (malaise, fever), followed by painful cutaneous and mucous membrane (ocular, oral, and genital) lesions, and other systemic symptoms."
    explanation: >
      Lerch et al. (2018) describe the influenza-like prodrome featuring malaise as
      universal in SJS/TEN, preceding the characteristic skin and mucous membrane lesions.
- name: Skin Pain and Burning
  category: Dermatological
  frequency: VERY_FREQUENT
  description: >
    Cutaneous pain and burning sensation, often described as severe and debilitating,
    are cardinal symptoms of SJS that typically precede visible skin detachment.
    The Nikolsky sign (sloughing on lateral pressure) is positive, and even gentle
    contact causes pain. Pain management is a major component of supportive care.
  phenotype_term:
    preferred_term: Pain
    term:
      id: HP:0012531
      label: Pain
  evidence:
  - reference: PMID:29188475
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "SJS/TEN manifest with an \"influenza-like\" prodromal phase (malaise, fever), followed by painful cutaneous and mucous membrane (ocular, oral, and genital) lesions, and other systemic symptoms."
    explanation: >
      Lerch et al. (2018) describe cutaneous lesions in SJS/TEN as explicitly painful,
      directly supporting skin pain as a cardinal symptom of the acute disease.
- name: Renal Complications
  category: Renal
  frequency: FREQUENT
  description: >
    Acute kidney injury and renal insufficiency occur as systemic complications of
    SJS/TEN, reflecting fluid loss from extensive skin and mucosal erosions as well
    as direct inflammatory involvement. Renal complications are among the most
    common systemic complications alongside ocular and cutaneous sequelae.
  phenotype_term:
    preferred_term: Renal insufficiency
    term:
      id: HP:0000083
      label: Renal insufficiency
  evidence:
  - reference: PMID:29188475
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In SJS/TEN, the most common complications are ocular, cutaneous, or renal."
    explanation: >
      Lerch et al. (2018) explicitly identify renal complications among the most common
      manifestations of SJS/TEN, supporting renal insufficiency as a recognized phenotypic
      feature requiring monitoring.
- name: Hepatic Involvement
  category: Hepatic
  frequency: FREQUENT
  description: >
    Transaminase elevation and hepatitic involvement occurs frequently in SJS/TEN,
    reflecting systemic immune activation and possible drug-induced hepatotoxicity
    from the same causative agent. Hepatic involvement may complicate management
    and drug dosing calculations.
  phenotype_term:
    preferred_term: Elevated hepatic transaminase
    term:
      id: HP:0002910
      label: Elevated circulating hepatic transaminase concentration
  evidence:
  - reference: PMID:29188475
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Pulmonary and hepatic involvement is frequent."
    explanation: >
      Lerch et al. (2018) explicitly state that hepatic involvement is frequent in
      SJS/TEN, supporting it as a recognized phenotypic complication.
environmental:
- name: High-Risk Drug Exposure
  description: >
    Medications are the predominant trigger. Highest-risk drugs include anti-infective
    sulfonamides (trimethoprim-sulfamethoxazole; relative risk 172), aromatic
    anticonvulsants (carbamazepine RR 90, phenytoin RR 53), allopurinol (RR 52),
    oxicam NSAIDs (RR 72), and nevirapine. Risk is highest within the first 8 weeks
    of drug exposure for long-term medications.
  evidence:
  - reference: PMID:7477195
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Among drugs usually used for short periods, the risks were increased for trimethoprim-sulfamethoxazole and other sulfonamide antibiotics (crude relative risk, 172; 95 percent confidence interval, 75 to 396)"
    explanation: >
      The landmark NEJM case-control study by Roujeau et al. (1995) quantified specific
      drug relative risks for SJS/TEN, identifying sulfonamide antibiotics as the
      highest-risk short-term medications.
  - reference: PMID:29188475
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Besides conventional drugs, herbal remedies and new biologicals should be considered as causative agents."
    explanation: >
      Lerch et al. (2018) expand the list of environmental triggers beyond conventional
      medications to include herbal remedies and biologics.
genetic:
- name: HLA-B*15:02 Allele
  notes: >
    HLA-B*15:02 is a strong genetic risk factor for carbamazepine-induced SJS/TEN,
    predominantly in Southeast Asian populations (Han Chinese, Thai, Malaysian).
    The allele has sensitivity of 100% and specificity of 97% for carbamazepine-induced
    SJS/TEN in Taiwan, with an odds ratio of 2504. Routine pre-prescription HLA
    genotyping is now recommended in these populations.
  evidence:
  - reference: PMID:29793265
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In the case of carbamazepine-induced SJS/TEN, the tight association of the HLA-B*1502 allele (sensitivity 100%, specificity 97% and odds ratio 2504) provides a plausible basis for further development of such a test to identify individuals at risk of developing this life-threatening condition."
    explanation: >
      Hung et al. (2005) established the extraordinary strength of the HLA-B*1502
      association with carbamazepine-induced SJS/TEN, providing the evidence basis
      for pharmacogenomic screening guidelines.
- name: HLA-B*58:01 Allele
  notes: >
    HLA-B*58:01 is strongly associated with allopurinol-induced SJS/TEN, particularly
    in Han Chinese and other Asian populations. Allopurinol is a leading cause of
    SJS/TEN in Asia, where HLA-B*58:01 carrier frequency is higher than in European
    populations.
  evidence:
  - reference: PMID:22541332
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The patho-mechanism involving HLA-restricted presentation of a drug or its metabolites for T-cell activation is supported by the findings of strong genetic associations with HLA alleles (e.g. HLA-B*15:02 and carbamazepine-SJS/TEN, and HLA-B*58:01 and allopurinol-SJS/TEN)."
    explanation: >
      Chung and Hung (2012) confirm HLA-B*58:01 as a key genetic risk factor for
      allopurinol-induced SJS/TEN, alongside HLA-B*15:02 for carbamazepine.
- name: HLA-A*31:01 Allele
  notes: >
    HLA-A*31:01 confers risk of carbamazepine-induced SJS/TEN, hypersensitivity
    syndrome, and maculopapular exanthema in Northern European populations
    (allele prevalence 2–5%). Genome-wide association data establish odds ratios
    of ~25.93 for SJS/TEN in carriers, increasing the carbamazepine reaction risk
    from 5% to 26%. The allele is also a risk factor in Japanese populations and
    has informed pharmacogenomic prescribing recommendations beyond the original
    HLA-B*15:02 Asian-population paradigm.
  evidence:
  - reference: PMID:21428769
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The presence of the HLA-A*3101 allele was associated with carbamazepine-induced hypersensitivity reactions among subjects of Northern European ancestry."
    explanation: >
      McCormack et al. (2011 NEJM) established HLA-A*31:01 as a strong, replicated
      determinant of carbamazepine-induced hypersensitivity (including SJS/TEN)
      in European-ancestry populations, broadening the HLA risk-allele paradigm.
  - reference: PMID:21428769
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The presence of the allele increased the risk from 5.0% to 26.0%, whereas its absence reduced the risk from 5.0% to 3.8%."
    explanation: >
      McCormack et al. (2011) quantified the absolute risk shift conferred by
      HLA-A*31:01, supporting clinical pharmacogenomic screening recommendations.
biochemical:
- name: Elevated Serum Urea
  presence: Elevated
  context: SCORTEN criterion; >10 mmol/L is an independent predictor of mortality
  evidence:
  - reference: PMID:10951229
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "serum urea above 10 mmol per liter"
    explanation: >
      Bastuji-Garin et al. (2000) identified elevated serum urea (>10 mmol/L) as one
      of seven independent risk factors for death in TEN/SJS, constituting a SCORTEN
      severity-of-illness criterion.
- name: Low Serum Bicarbonate
  presence: Decreased
  context: SCORTEN criterion; <20 mmol/L is an independent predictor of mortality
  evidence:
  - reference: PMID:10951229
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "bicarbonate below 20 mmol per liter"
    explanation: >
      Bastuji-Garin et al. (2000) identified bicarbonate below 20 mmol/L as one of
      seven independent risk factors for death in TEN/SJS within the SCORTEN score.
- name: Elevated Blood Glucose
  presence: Elevated
  context: SCORTEN criterion; >14 mmol/L is an independent predictor of mortality
  evidence:
  - reference: PMID:10951229
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "serum glucose above 14 mmol per liter"
    explanation: >
      Bastuji-Garin et al. (2000) identified elevated blood glucose (>14 mmol/L) as one
      of seven independent risk factors for death in TEN/SJS within the SCORTEN score.
- name: Elevated C-Reactive Protein
  presence: Elevated
  context: Nonspecific acute-phase reactant; reflects systemic inflammatory response
- name: Elevated Soluble FasL
  presence: Elevated
  context: Elevated in SJS and TEN; potential early diagnostic biomarker
  evidence:
  - reference: PMID:12707034
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the serum sFasL level may be a good indicator for the early diagnosis of TEN and SJS."
    explanation: >
      Abe et al. (2003) demonstrated elevated soluble FasL in SJS and TEN patients versus
      controls, supporting sFasL as a potential biochemical marker for early diagnosis.
histopathology:
- name: Full-Thickness Epidermal Necrosis
  description: >
    The hallmark histopathological finding in SJS is confluent full-thickness epidermal
    necrosis, contrasting with the focal necrosis of erythema multiforme. Necrotic
    keratinocytes appear as eosinophilic "ghost cells" throughout all epidermal layers,
    reflecting the massive CTL/NK cell-mediated apoptosis. Subepidermal blister formation
    with detachment of the entire epidermis from the dermis occurs as necrosis progresses.
  evidence:
  - reference: PMID:29188475
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The diagnosis of different degrees of epidermal necrolysis is based on the clinical assessment in conjunction with the corresponding histopathology."
    explanation: >
      Lerch et al. (2018) describe histopathological confirmation as integral to SJS/TEN
      diagnosis, supporting epidermal necrolysis as the defining histopathological finding.
  - reference: PMID:22541332
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "granulysin, a cytotoxic protein produced by CTLs or natural killer (NK) cells, is the key mediator for disseminated keratinocyte death in SJS/TEN."
    explanation: >
      Chung and Hung (2012) confirm that disseminated keratinocyte death by granulysin
      is the molecular basis for the widespread epidermal necrosis seen histopathologically.
- name: Lymphocytic Interface Dermatitis with Cytotoxic Infiltrate
  description: >
    Biopsy of early SJS lesions shows lymphocytic infiltrate at the dermoepidermal
    junction with vacuolar degeneration of basal keratinocytes (interface dermatitis pattern)
    and satellite cell necrosis. Blister cells are predominantly CD8+ CTLs with strong
    granzyme B immunoreactivity. This pattern distinguishes SJS/TEN from other blistering
    disorders and from morbilliform drug eruptions.
  evidence:
  - reference: PMID:15536433
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Blister cells showed a strong immunoreactivity for granzyme B, and cytotoxicity was abolished by EGTA, but not by anti-Fas/CD95, suggesting perforin/granzyme-mediated killing."
    explanation: >
      Nassif et al. (2004) characterized the blister cell infiltrate in TEN/SJS as
      granzyme B-positive cytotoxic T lymphocytes, directly describing the histopathological
      cellular composition of the infiltrate.
  - reference: PMID:19029983
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "blister cells from skin lesions of SJS-TEN primarily consist of cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells, and both blister fluids and cells were cytotoxic."
    explanation: >
      Chung et al. (2008) confirmed that the cellular infiltrate in SJS-TEN skin lesions
      consists predominantly of CTLs and NK cells with cytotoxic activity, supporting the
      lymphocytic interface dermatitis pattern.
definitions:
- name: SCORTEN Severity-of-Illness Score
  definition_type: DIAGNOSTIC_CRITERIA
  description: >
    SCORTEN (SCORe of Toxic Epidermal Necrosis) is a validated 7-parameter prognostic
    severity-of-illness score for SJS/TEN that predicts hospital mortality. Each parameter
    present scores 1 point. Total score 0-1 predicts ~3% mortality; score 2 predicts ~12%;
    score 3 predicts ~35%; score 4 predicts ~58%; score ≥5 predicts >90% mortality.
  scope: Adults with SJS, SJS/TEN overlap, or TEN admitted to hospital; validated
    for mortality prediction
  evidence:
  - reference: PMID:10951229
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This study demonstrates that the risk of death of toxic epidermal necrolysis patients can be accurately predicted by the toxic epidermal necrolysis-specific severity-of-illness score."
    explanation: >
      Bastuji-Garin et al. (2000) developed and validated SCORTEN using 165 patients
      (development) and 75 (validation), demonstrating excellent calibration and
      discrimination for predicting hospital mortality in TEN/SJS.
  criteria_sets:
  - name: SCORTEN parameters (7 independent risk factors for death)
    description: >
      Seven independent risk factors for death, each scored 0 (absent) or 1 (present).
      Parameters: (1) age >40 years, (2) malignancy, (3) tachycardia >120/min,
      (4) initial epidermal detachment >10% BSA, (5) serum urea >10 mmol/L,
      (6) serum glucose >14 mmol/L, (7) bicarbonate <20 mmol/L.
    minimum_required: 0
    evidence:
    - reference: PMID:10951229
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "We identified seven independent risk factors for death and constituted the toxic epidermal necrolysis-specific severity-of-illness score: age above 40 y, malignancy, tachycardia above 120 per min, initial percentage of epidermal detachment above 10%, serum urea above 10 mmol per liter, serum glucose above 14 mmol per liter, and bicarbonate below 20 mmol per liter."
      explanation: >
        Bastuji-Garin et al. (2000) developed and validated SCORTEN using 165 patients
        (development) and 75 patients (validation), demonstrating excellent calibration
        (ROC area 82%) for predicting hospital mortality in TEN/SJS.
treatments:
- name: Immediate Drug Withdrawal
  description: >
    Prompt identification and cessation of the offending drug is the single most
    critical intervention in SJS management. Earlier withdrawal is associated with
    improved survival, as each additional day of exposure to the causative drug
    worsens outcomes.
  target_mechanisms:
  - target: Drug-HLA Direct Interaction
    treatment_effect: INHIBITS
    description: >
      Removing the causative drug eliminates the molecular trigger for HLA-mediated
      antigen presentation, terminating new CTL activation at the most upstream
      pharmacological node of the SJS/TEN pathograph.
    evidence:
    - reference: PMID:28476287
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Early drug withdrawal is mandatory in all SCARs."
      explanation: >
        Duong et al. (2017) state unequivocally that early drug withdrawal is
        mandatory in SCARs, supporting drug withdrawal as the canonical upstream
        intervention targeting the drug–HLA interaction node.
  evidence:
  - reference: PMID:28476287
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Early drug withdrawal is mandatory in all SCARs."
    explanation: >
      Duong et al. (2017 Lancet) unequivocally state that early drug withdrawal is
      mandatory in all severe cutaneous adverse reactions including SJS/TEN, reflecting
      the clinical consensus view.
- name: Specialized Supportive Care
  description: >
    Management in burn centers or ICU settings with expertise in wound care, fluid
    and electrolyte replacement, nutritional support, temperature regulation, pain
    control, and infection prevention is associated with improved survival. Given
    the similarity to burn injuries, burn unit care is the cornerstone of management.
  treatment_term:
    preferred_term: supportive care
    term:
      id: MAXO:0000950
      label: supportive care
  evidence:
  - reference: PMID:34577817
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) are rare diseases that are characterized by widespread epidermal necrosis and sloughing of skin. They are associated with significant morbidity and mortality, and early diagnosis and treatment is critical in achieving favorable outcomes for patients."
    explanation: >
      Frantz et al. (2021) emphasize that early diagnosis and treatment — including
      specialized supportive care — is critical for favorable outcomes in SJS/TEN.
- name: Cyclosporine
  description: >
    Cyclosporine A is the most effective immunosuppressive therapy for SJS, halting
    disease progression by suppressing CTL activity and blocking further
    keratinocyte killing. Multiple retrospective and prospective studies support its
    use in SJS, and it is considered first-line immunosuppressive treatment.
  treatment_term:
    preferred_term: cyclosporine immunosuppression
    term:
      id: MAXO:0000058
      label: pharmacotherapy
  target_mechanisms:
  - target: Drug-Specific Cytotoxic T Cell Activation
    treatment_effect: INHIBITS
    description: >
      Calcineurin inhibition by cyclosporine A blocks T cell receptor signalling
      and clonal expansion of drug-specific CD8+ CTLs, halting the upstream
      effector node of the SJS/TEN pathograph.
    evidence:
    - reference: PMID:34577817
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "cyclosporine is the most effective therapy for the treatment of SJS"
      explanation: >
        Frantz et al. (2021) identify cyclosporine as the most effective SJS
        therapy, consistent with its mechanism of suppressing the drug-specific
        CTL activation node.
  target_phenotypes:
  - preferred_term: Skin detachment
    term:
      id: HP:0032156
      label: Skin detachment
  evidence:
  - reference: PMID:34577817
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "cyclosporine is the most effective therapy for the treatment of SJS, and a combination of intravenous immunoglobulin (IVIg) and corticosteroids is most effective for SJS/TEN overlap and TEN."
    explanation: >
      Frantz et al. (2021) identify cyclosporine as the most effective treatment
      specifically for SJS, distinguishing its role from IVIG+corticosteroids for
      TEN and SJS/TEN overlap.
  - reference: PMID:29188475
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The most frequently used treatments for SJS/TEN are systemic corticosteroids, immunoglobulins, and cyclosporine A."
    explanation: >
      Lerch et al. (2018) confirm cyclosporine A as one of the most frequently used
      treatments for SJS/TEN in clinical practice.
- name: Intravenous Immunoglobulin
  description: >
    IVIG has been used to block Fas–FasL mediated apoptosis and modulate the immune
    response. Evidence for SJS-specific efficacy is mixed; combined IVIG with
    corticosteroids appears most effective for SJS/TEN overlap and TEN.
  treatment_term:
    preferred_term: intravenous immunoglobulin therapy
    term:
      id: MAXO:0000058
      label: pharmacotherapy
  target_mechanisms:
  - target: Fas-FasL Keratinocyte Apoptosis
    treatment_effect: INHIBITS
    description: >
      Anti-Fas blocking antibodies present in pooled IVIG are proposed to neutralise
      keratinocyte Fas engagement by sFasL, attenuating extrinsic-pathway apoptosis
      of keratinocytes.
    evidence:
    - reference: PMID:34577817
      supports: PARTIAL
      evidence_source: HUMAN_CLINICAL
      snippet: "a combination of intravenous immunoglobulin (IVIg) and corticosteroids is most effective for SJS/TEN overlap and TEN."
      explanation: >
        Frantz et al. (2021) describe IVIG efficacy in SJS/TEN overlap and TEN; the
        canonical mechanistic proposal is anti-Fas neutralisation of the Fas-FasL
        keratinocyte apoptosis node, but evidence is indirect — hence PARTIAL.
  target_phenotypes:
  - preferred_term: Skin detachment
    term:
      id: HP:0032156
      label: Skin detachment
  evidence:
  - reference: PMID:34577817
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "a combination of intravenous immunoglobulin (IVIg) and corticosteroids is most effective for SJS/TEN overlap and TEN. Due to the rare nature of the disease, there is a lack of prospective, randomized controlled trials and conducting these in the future would provide valuable insights into the management of this disease."
    explanation: >
      Frantz et al. (2021) support IVIG use primarily for SJS/TEN overlap and TEN
      rather than isolated SJS, and acknowledge the lack of RCT-level evidence —
      hence the PARTIAL support rating.
- name: Systemic Corticosteroids
  description: >
    Systemic corticosteroids (e.g., dexamethasone, methylprednisolone) are among
    the most frequently used treatments for SJS/TEN despite ongoing controversy
    about benefit versus risk. They suppress immune activation and CTL-mediated
    keratinocyte killing but may increase infection risk in patients with open
    skin wounds. Short-course pulse regimens may reduce harm while capitalizing
    on anti-inflammatory efficacy.
  treatment_term:
    preferred_term: corticosteroid therapy
    term:
      id: NCIT:C122080
      label: Systemic Corticosteroid Therapy
  target_mechanisms:
  - target: Drug-Specific Cytotoxic T Cell Activation
    treatment_effect: INHIBITS
    description: >
      Glucocorticoid signalling broadly suppresses T cell activation, cytokine
      transcription (including IL-15-amplification cytokines), and CTL effector
      function, dampening upstream drivers of keratinocyte killing.
    evidence:
    - reference: PMID:29188475
      supports: PARTIAL
      evidence_source: HUMAN_CLINICAL
      snippet: "The most frequently used treatments for SJS/TEN are systemic corticosteroids, immunoglobulins, and cyclosporine A."
      explanation: >
        Lerch et al. (2018) confirm corticosteroids as a frequently used SJS/TEN
        therapy; the proposed mechanistic target is the upstream CTL activation
        node, though benefit-vs-risk evidence is mixed (PARTIAL).
  target_phenotypes:
  - preferred_term: Skin detachment
    term:
      id: HP:0032156
      label: Skin detachment
  evidence:
  - reference: PMID:29188475
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "The most frequently used treatments for SJS/TEN are systemic corticosteroids, immunoglobulins, and cyclosporine A."
    explanation: >
      Lerch et al. (2018) confirm systemic corticosteroids as one of the most frequently
      used treatments for SJS/TEN in clinical practice. However, evidence of benefit is
      not definitive, hence PARTIAL support; they are widely used but remain controversial.
- name: Amniotic Membrane Transplantation
  description: >
    Timely placement of amniotic membrane (or ProKera devices) on the ocular
    surface during the acute phase of SJS/TEN suppresses ocular surface
    inflammation, prevents conjunctival scarring and symblepharon formation,
    and reduces the risk of chronic ocular surface disease and bilateral
    blindness — the dominant long-term morbidity of SJS/TEN survivorship.
    Acute-phase ophthalmic surveillance with prompt amniotic membrane therapy
    is a cornerstone of SJS/TEN ocular care.
  treatment_term:
    preferred_term: amniotic membrane transplantation
    term:
      id: MAXO:0000004
      label: surgical procedure
  target_phenotypes:
  - preferred_term: Conjunctivitis
    term:
      id: HP:0000509
      label: Conjunctivitis
  - preferred_term: Symblepharon
    term:
      id: HP:0430007
      label: Symblepharon
  - preferred_term: Corneal scarring
    term:
      id: HP:0000559
      label: Corneal scarring
  evidence:
  - reference: PMID:37140876
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Early diagnosis, timely amniotic membrane transplantation and aggressive topical management in acute SJS/TEN are necessary to prevent long-term, chronic ocular complications."
    explanation: >
      Tóth et al. (2023 Ophthalmol Ther) — narrative review of SJS/TEN ocular
      management — establish timely amniotic membrane transplantation in the
      acute phase as a key intervention to prevent severe chronic ocular
      complications.
- name: TNF Inhibitor Therapy
  description: >
    Biologic TNF blockade (e.g., infliximab, etanercept) is an emerging targeted
    therapy with mechanistic rationale grounded in 2024 single-cell evidence
    that TNF signalling drives macrophage CXCL10 production and downstream
    CXCR3+ CTL recruitment in immune checkpoint inhibitor (ICI)–induced
    SJS/TEN. In the Chen et al. (2024 Nat Commun) ICI-induced SJS/TEN cohort,
    biologic TNF blockade produced significantly faster recovery than systemic
    corticosteroids and allowed continuation of ICI therapy without SCAR
    recurrence. The role of anti-TNF for non-ICI-induced SJS/TEN remains
    investigational and is being explored in current reviews.
  treatment_term:
    preferred_term: pharmacotherapy
    term:
      id: MAXO:0000058
      label: pharmacotherapy
    therapeutic_agent:
    - preferred_term: monoclonal antibody
      term:
        id: NCIT:C20401
        label: Monoclonal Antibody
  target_mechanisms:
  - target: Macrophage CXCL10-CXCR3 / TNF Amplification
    treatment_effect: INHIBITS
    description: >
      Anti-TNF biologic therapy directly inhibits the TNF signalling node that
      drives macrophage CXCL10 output and CXCR3+ CTL recruitment in ICI-induced
      SJS/TEN, breaking the amplification loop.
    evidence:
    - reference: PMID:39737932
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "patients treated with biologic TNF blockade showed a significantly rapid recovery and no recurrence of SCAR with continuous ICI therapy."
      explanation: >
        Chen et al. (2024) clinically validated that pharmacological TNF
        blockade hits this amplification node and improves outcomes in
        ICI-induced SJS/TEN.
  target_phenotypes:
  - preferred_term: Skin detachment
    term:
      id: HP:0032156
      label: Skin detachment
  evidence:
  - reference: PMID:39737932
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Compared with systemic corticosteroids treatment, ICI-induced SJS/TEN patients treated with biologic TNF blockade showed a significantly rapid recovery and no recurrence of SCAR with continuous ICI therapy."
    explanation: >
      Chen et al. (2024 Nat Commun) demonstrated superior outcomes for biologic
      TNF blockade versus systemic corticosteroids in ICI-induced SJS/TEN,
      establishing anti-TNF as a mechanism-targeted therapy in this setting.
  - reference: PMID:39238098
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Recent studies have investigated the potential benefits of tumor necrosis factor-α antagonists."
    explanation: >
      Hasegawa & Abe (2024) flag TNF-α antagonists as an actively investigated
      therapeutic option in SJS/TEN beyond the ICI-induced subset; PARTIAL
      because broader (non-ICI) RCT-level evidence is still limited.
epidemiology:
- name: In-hospital mortality (multicenter SJS/TEN cohort, Turkey 2012–2022)
  description: >
    Prospective multicenter cohort of 166 SJS/TEN patients across 12 tertiary
    centers documenting in-hospital mortality and mortality risk by SCORTEN
    stratum.
  mean_range: "24.1"
  unit: percent
  notes: >
    SCORTEN ≥5 conferred an 84-fold mortality risk versus SCORTEN 0–1
    (multivariate OR 84, 95% CI 13.9–507.5).
  evidence:
  - reference: PMID:38758423
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "While 66.3% of patients were discharged, 24.1% resulted in exitus."
    explanation: >
      Erduran et al. (2024 Dermatol Ther) — multicenter retrospective cohort
      (n=166, 12 tertiary centers, 2012–2022) — reports in-hospital mortality
      of 24.1% in SJS/TEN, providing a contemporary epidemiology anchor.
- name: SCORTEN-stratified mortality risk (Erduran 2024 multicenter cohort)
  description: >
    Multivariate odds ratios for in-hospital mortality at increasing SCORTEN
    strata, demonstrating exponential mortality risk rise above SCORTEN 2.
  notes: >
    Mortality OR for SCORTEN 5–6 was 84 versus SCORTEN 0–1; OR 22 for
    plasmapheresis utilization (likely confounded by severity).
  evidence:
  - reference: PMID:38758423
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Multivariate regression analysis indicated that over SCORTEN 2, the mortality risk exponentially rose with each SCORTEN increment, culminating in an 84-fold increase in mortality at SCORTEN 5-6"
    explanation: >
      Erduran et al. (2024) quantify the steep mortality gradient with SCORTEN
      stratum in a contemporary multicenter SJS/TEN cohort — anchoring the
      prognostic value of SCORTEN above the original Bastuji-Garin (2000)
      derivation.
classifications:
  harrisons_chapter:
  - classification_value: skin disorder
    evidence:
    - reference: PMID:34577817
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) are rare diseases that are characterized by widespread epidermal necrosis and sloughing of skin."
      explanation: >
        Frantz et al. (2021) describe SJS/TEN by its cutaneous manifestations — epidermal
        necrosis and skin sloughing — confirming its classification as a skin disorder.
  - classification_value: immune system disorder
    evidence:
    - reference: PMID:22541332
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The recent studies suggested that SJS/TEN is a specific immune reaction initiated by the cytotoxic T lymphocytes (CTLs) via human leukocyte antigens (HLAs)-restricted pathway."
      explanation: >
        Chung and Hung (2012) describe SJS/TEN as a specific immune reaction mediated
        by cytotoxic T lymphocytes, supporting classification as an immune system disorder.
  - classification_value: allergic disease
    evidence:
    - reference: PMID:28476287
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "SCARS are potentially life threatening, and associated with various clinical patterns and morbidity during the acute stage of Stevens-Johnson syndrome and toxic epidermal necrolysis"
      explanation: >
        Duong et al. (2017 Lancet) categorize SJS/TEN as a severe cutaneous adverse
        reaction (SCAR) to drugs — a form of drug hypersensitivity/allergic disease.
datasets: []

📚

References & Deep Research

Deep Research

1

Falcon ▸

Disease Characteristics Research Template

Edison Scientific Literature 38 citations 2026-04-26T20:26:34.022099

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on: 1. Key concepts and definitions with current understanding 2. Recent developments and latest research (prioritize 2023-2024 sources) 3. Current applications and real-world implementations 4. Expert opinions and analysis from authoritative sources 5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available. Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Disease Characteristics Research Template

Target Disease

Disease Name: Stevens-Johnson Syndrome
MONDO ID: (if available)
Category: Complex

Research Objectives

Please provide a comprehensive research report on Stevens-Johnson Syndrome covering all of the disease characteristics listed below. This report will be used to populate a disease knowledge base entry. Be thorough and cite primary literature (PMID preferred) for all claims.

For each section, suggested databases/resources are listed. These are the first places you should search for information on each topic.

1. Disease Information

Search first: OMIM, Orphanet, ICD-10/ICD-11, MeSH, PubMed

What is the disease? Provide a concise overview.
What are the key identifiers? (OMIM, Orphanet, ICD-10/ICD-11, MeSH, Mondo)
What are the common synonyms and alternative names?
Is the information derived from individual patients (e.g., EHR) or aggregated disease-level resources?

2. Etiology

Disease Causal Factors: What are the primary causes? (genetic, environmental, infectious, mechanistic)
Risk Factors:

Search first: PubMed, Cochrane Library, UpToDate, clinical guidelines, ClinVar, ClinGen, GWAS Catalog, PheGenI, CTD, CDC, WHO, epidemiological databases
Genetic risk factors (causal variants, susceptibility loci, modifier genes)
Environmental risk factors (toxins, lifestyle, occupational exposures, age, sex, family history)
Protective Factors:

Search first: PubMed, Cochrane Library, clinical trial databases, GWAS Catalog, gnomAD, WHO, CDC, nutrition databases
Genetic protective factors (protective variants, modifier alleles)
Environmental protective factors (diet, lifestyle, exposures that reduce risk)
Gene-Environment Interactions: How do genetic and environmental factors interact to influence disease?

Search first: CTD, PubMed, PheGenI, GxE databases

3. Phenotypes

Search first: HPO (Human Phenotype Ontology), OMIM, Orphanet, PubMed, clinicaltrials.gov, MedDRA, SNOMED CT, DECIPHER, LOINC

For each phenotype, provide: - Phenotype type: symptoms, clinical signs, physical manifestations, behavioral changes, or laboratory abnormalities

For symptoms/signs: HPO, OMIM, Orphanet, PubMed For behavioral changes: HPO, DSM, RDoC (Research Domain Criteria), PubMed For laboratory abnormalities: LOINC, SNOMED CT, LabTests Online, PubMed - Phenotype characteristics: Search first: OMIM, Orphanet, HPO, PubMed - Age of symptom onset (neonatal, childhood, adult-onset, late-onset) - Symptom severity (mild, moderate, severe, variable) - Symptom progression (stable, progressive, episodic, fluctuating) - Frequency among affected individuals (percentage or qualitative) - Quality of life impact: Effects on daily functioning and well-being (per-phenotype when possible) Search first: EQ-5D database, SF-36, WHO QOL databases, PubMed - Suggest HPO (Human Phenotype Ontology) terms for each phenotype

4. Genetic/Molecular Information

Causal Genes: Gene mutations or chromosomal abnormalities responsible for disease (gene symbols, OMIM IDs)

Search first: OMIM, ClinVar, HGMD, Ensembl, NCBI Gene
Pathogenic Variants:
Affected genes (gene symbols, HGNC IDs) > Search first: OMIM, NCBI Gene, Ensembl, HGNC, UniProt, GeneCards
Variant classification (pathogenic, likely pathogenic, VUS per ACMG/AMP guidelines) > Search first: ClinVar, ClinGen, ACMG/AMP guidelines, VarSome
Variant type/class (missense, frameshift, nonsense, splice-site, structural)
Allele frequency in population databases > Search first: gnomAD, 1000 Genomes, ExAC, TOPMed, dbSNP
Somatic vs germline origin > Search first: COSMIC (somatic), ClinVar, ICGC, TCGA
Functional consequences (loss of function, gain of function, dominant negative)
Modifier Genes: Genes that modify disease severity or expression
Epigenetic Information: DNA methylation, histone modifications, chromatin changes affecting disease

Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth
Chromosomal Abnormalities: Large-scale genetic changes (aneuploidy, translocations, inversions)

Search first: DECIPHER, ClinVar, ECARUCA, UCSC Genome Browser

5. Environmental Information

Environmental Factors: Non-genetic contributing factors (toxins, radiation, pollution, occupational exposure)

Search first: CTD (Comparative Toxicogenomics Database), TOXNET, PubMed, EPA databases
Lifestyle Factors: Behavioral factors (smoking, diet, exercise, alcohol consumption)

Search first: CDC databases, WHO, PubMed, NHANES
Infectious Agents: If applicable, pathogens causing or triggering disease (bacteria, viruses, fungi, parasites)

Search first: NCBI Taxonomy, ViPR, BV-BRC, MicrobeDB, GIDEON

6. Mechanism / Pathophysiology

Molecular Pathways: Specific signaling cascades or biochemical pathways involved (Wnt, MAPK, mTOR, PI3K-AKT, etc.)

Search first: KEGG, Reactome, WikiPathways, PathBank, BioCyc
Cellular Processes: Cell-level mechanisms (apoptosis, autophagy, cell cycle dysregulation, inflammation, etc.)

Search first: Gene Ontology (GO), Reactome, KEGG, PubMed
Protein Dysfunction: How protein structure or function is altered (misfolding, aggregation, loss of function, gain of function)

Search first: UniProt, PDB (Protein Data Bank), InterPro, Pfam, AlphaFold
Metabolic Changes: Alterations in metabolic processes (energy metabolism, lipid metabolism, amino acid metabolism)

Search first: KEGG, BioCyc, HMDB (Human Metabolome Database), BRENDA
Immune System Involvement: Role of immune response (autoimmunity, immunodeficiency, chronic inflammation)

Search first: ImmPort, Immunome Database, IEDB, Gene Ontology
Tissue Damage Mechanisms: How tissues/ are injured (oxidative stress, ischemia, fibrosis, necrosis)

Search first: PubMed, Gene Ontology, Reactome
Biochemical Abnormalities: Specific molecular defects (enzyme deficiencies, receptor dysfunction, ion channel defects)

Search first: BRENDA, UniProt, KEGG, OMIM, PubMed
Epigenetic Changes: DNA methylation, histone modifications affecting gene expression in disease

Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth
Molecular Profiling (if available):
Transcriptomics/gene expression changes > Search first: GEO (Gene Expression Omnibus), ArrayExpress, GTEx, Human Cell Atlas, SRA
Proteomics findings > Search first: PRIDE, ProteomeXchange, Human Protein Atlas, STRING, BioGRID
Metabolomics signatures > Search first: MetaboLights, Metabolomics Workbench, HMDB, METLIN
Lipidomics alterations > Search first: LIPID MAPS, SwissLipids, LipidHome, Metabolomics Workbench
Genomic structural features > Search first: UCSC Genome Browser, Ensembl, NCBI, dbVar, DGV
Advanced Technologies (if applicable):
Single-cell analysis findings (cell-type specific mechanisms, cellular heterogeneity) > Search first: Human Cell Atlas, Single Cell Portal, GEO, CELLxGENE
Spatial transcriptomics findings > Search first: GEO, Spatial Research, Vizgen, 10x Genomics data
Multi-omics integration results > Search first: TCGA, ICGC, cBioPortal, LinkedOmics, PubMed
Functional genomics screens (CRISPR, RNAi) > Search first: DepMap, GenomeRNAi, PubMed, BioGRID ORCS

For each mechanism, describe: - The causal chain from initial trigger to clinical manifestation - Which mechanisms are upstream vs downstream - What cell types and biological processes are involved - Suggest GO terms for biological processes and CL terms for cell types

7. Anatomical Structures Affected

Organ Level:
Primary organs directly affected
Secondary organ involvement (complications, secondary effects)
Body systems involved (cardiovascular, nervous, digestive, respiratory, endocrine, etc.)

Search first: Uberon, FMA (Foundational Model of Anatomy), OMIM, HPO, ICD-11, MeSH, SNOMED CT
Tissue and Cell Level:
Specific tissue types affected (epithelial, connective, muscle, nervous)
Specific cell populations targeted (with Cell Ontology terms)

Search first: Uberon, Human Protein Atlas, Cell Ontology, Human Cell Atlas, CellMarker, PanglaoDB
Subcellular Level:
Cellular compartments involved (mitochondria, nucleus, ER, lysosomes) (with GO Cellular Component terms)

Search first: Gene Ontology (Cellular Component), UniProt, Human Protein Atlas
Localization:
Specific anatomical sites (with UBERON terms) > Search first: FMA, Uberon, NeuroNames (for brain), SNOMED CT
Lateralization (unilateral, bilateral, asymmetric) > Search first: HPO, clinical literature, imaging databases

8. Temporal Development

Onset:
Typical age of onset (congenital, pediatric, adult, geriatric)
Onset pattern (acute, subacute, chronic, insidious)

Search first: OMIM, Orphanet, HPO, PubMed
Progression:
Disease stages (early, intermediate, advanced, end-stage) > Search first: Cancer Staging Manual (AJCC), WHO classifications, PubMed
Progression rate (rapid, slow, variable)
Disease course pattern (episodic, relapsing-remitting, progressive, stable)
Disease duration (self-limited, chronic lifelong)

Search first: Disease registries, longitudinal cohort databases, natural history studies, PubMed, Orphanet, OMIM
Patterns:
Remission patterns (spontaneous, treatment-induced) > Search first: Clinical trial databases, disease registries, PubMed
Critical periods (time windows of vulnerability or opportunity for intervention) > Search first: PubMed, developmental biology databases, clinical guidelines

9. Inheritance and Population

Epidemiology:
Prevalence (cases per 100,000 at given time)
Incidence (new cases per 100,000 per year)

Search first: Orphanet, CDC, WHO, GBD (Global Burden of Disease), national registries, SEER, disease registries
For Genetic Etiology:
Inheritance pattern (AD, AR, X-linked, mitochondrial, multifactorial, polygenic) > Search first: OMIM, Orphanet, ClinVar, GTR (Genetic Testing Registry)
Penetrance (complete, incomplete, age-dependent) > Search first: ClinVar, OMIM, PubMed, ClinGen
Expressivity (variable, consistent) > Search first: OMIM, ClinVar, PubMed
Genetic anticipation (increasing severity in successive generations) > Search first: OMIM, PubMed (especially for repeat expansion disorders)
Germline mosaicism > Search first: ClinVar, OMIM, genetic counseling literature, PubMed
Founder effects (population-specific mutations) > Search first: gnomAD, population genetics databases, PubMed
Consanguinity role > Search first: OMIM, population studies, genetic counseling resources
Carrier frequency > Search first: gnomAD, carrier screening databases, GeneReviews, GTR
Population Demographics:
Affected populations (ethnic or demographic groups with higher prevalence) > Search first: gnomAD, 1000 Genomes, PAGE Study, PubMed, population registries
Geographic distribution (endemic areas, regional variation) > Search first: WHO, CDC, GBD, Orphanet, geographic epidemiology databases
Geographic distribution of specific variants
Sex ratio (male:female) > Search first: Disease registries, OMIM, PubMed, epidemiological databases
Age distribution of affected individuals > Search first: CDC, disease registries, SEER, Orphanet

10. Diagnostics

Clinical Tests:
Laboratory tests (blood, urine, tissue chemistry, specific enzyme assays) > Search first: LOINC, LabTests Online, PubMed
Biomarkers (proteins, metabolites, genetic markers, circulating biomarkers) > Search first: FDA Biomarker List, BEST (Biomarkers, EndpointS, and other Tools), PubMed
Imaging studies (X-ray, CT, MRI, PET, ultrasound) > Search first: RadLex, DICOM, Radiopaedia, imaging databases
Functional tests (pulmonary function, cardiac stress tests) > Search first: LOINC, clinical guidelines, PubMed
Electrophysiology (EEG, EMG, ECG, nerve conduction studies) > Search first: LOINC, clinical neurophysiology databases, PubMed
Biopsy findings (histopathology, immunohistochemistry) > Search first: SNOMED CT, College of American Pathologists resources, PubMed
Pathology findings (microscopic examination) > Search first: SNOMED CT, Digital Pathology databases, PubMed
Genetic Testing:

Search first: GTR (Genetic Testing Registry), GeneReviews, ClinGen
Overview of recommended genetic testing approach
Whole genome sequencing (WGS) utility > Search first: GTR, ClinVar, GEL (Genomics England), gnomAD
Whole exome sequencing (WES) utility > Search first: GTR, ClinVar, OMIM, GeneMatcher
Gene panels (which panels, which genes) > Search first: GTR, ClinVar, laboratory-specific databases
Single gene testing > Search first: GTR, ClinVar, OMIM, GeneReviews
Chromosomal microarray (CMA) > Search first: DECIPHER, ClinVar, dbVar, ECARUCA
Karyotyping > Search first: Chromosome Abnormality Database, ClinVar, cytogenetics resources
FISH > Search first: ClinVar, cytogenetics databases, PubMed
Mitochondrial DNA testing > Search first: MITOMAP, MSeqDR, ClinVar, GTR
Repeat expansion testing > Search first: GTR, ClinVar, repeat expansion databases, PubMed
Omics-Based Diagnostics (if applicable):
RNA sequencing / transcriptomics > Search first: GEO, ArrayExpress, GTEx, RNA-seq databases
Proteomics > Search first: PRIDE, ProteomeXchange, FDA Biomarker database
Metabolomics > Search first: MetaboLights, Metabolomics Workbench, HMDB
Epigenomics > Search first: GEO, ENCODE, Roadmap Epigenomics, MethBase
Liquid biopsy > Search first: COSMIC, ClinVar, liquid biopsy databases, PubMed
Clinical Criteria:
Standardized diagnostic criteria (DSM, ICD, society guidelines) > Search first: DSM-5, ICD-11, clinical society guidelines, UpToDate
Differential diagnosis (other conditions to rule out, with distinguishing features) > Search first: DynaMed, UpToDate, clinical decision support systems
Screening:
Screening methods for asymptomatic individuals (newborn screening, carrier screening, cascade screening) > Search first: ACMG recommendations, CDC newborn screening, GTR

11. Outcome/Prognosis

Survival and Mortality:
Survival rate (5-year, 10-year, overall) > Search first: SEER, cancer registries, disease-specific registries, PubMed
Life expectancy (with and without treatment if applicable) > Search first: Orphanet, disease registries, actuarial databases, PubMed
Mortality rate > Search first: CDC, WHO, GBD, national mortality databases
Disease-specific mortality (deaths directly attributable to disease) > Search first: Disease registries, CDC Wonder, GBD, PubMed
Morbidity and Function:
Morbidity (disease-related disability and health impacts) > Search first: GBD, WHO, disability databases, PubMed
Disability outcomes (long-term functional impairments) > Search first: ICF (International Classification of Functioning), disability registries
Quality of life measures (EQ-5D, SF-36, PROMIS, disease-specific tools) > Search first: EQ-5D database, SF-36, PROMIS, PubMed
Disease Course:
Complications (secondary problems: infections, organ failure, etc.) > Search first: ICD codes, disease registries, clinical databases, PubMed
Recovery potential (likelihood and extent of recovery, with vs without treatment) > Search first: Natural history studies, rehabilitation databases, PubMed
Prediction:
Prognostic factors (age, disease severity, biomarkers, treatment response) > Search first: Prognostic models databases, clinical calculators, PubMed
Prognostic biomarkers (molecular markers predicting disease course) > Search first: FDA Biomarker database, PubMed, cancer prognostic databases

12. Treatment

Pharmacotherapy:
Pharmacological treatments (drug names, drug classes, mechanisms of action) > Search first: DrugBank, RxNorm, ATC classification, DailyMed, FDA databases
Pharmacogenomics (how genetic variants affect drug metabolism, efficacy, toxicity) > Search first: PharmGKB, CPIC (Clinical Pharmacogenetics), FDA Table of PGx Biomarkers
Advanced Therapeutics:
Gene therapy (viral vectors, CRISPR, gene replacement, gene editing) > Search first: ClinicalTrials.gov, FDA gene therapy database, ASGCT resources
Cell therapy (stem cell transplant, CAR-T, cellular therapeutics) > Search first: ClinicalTrials.gov, FDA cell therapy database, FACT standards
RNA-based therapies (ASOs, siRNA, mRNA therapies) > Search first: ClinicalTrials.gov, FDA approvals, PubMed
Targeted therapies (treatments directed at specific molecular targets) > Search first: My Cancer Genome, OncoKB, ClinicalTrials.gov, FDA approvals
Immunotherapies (checkpoint inhibitors, monoclonal antibodies) > Search first: Cancer Immunotherapy Database, FDA approvals, ClinicalTrials.gov
Surgical and Interventional:
Surgical interventions (types of surgery, timing, outcomes) > Search first: CPT codes, surgical registries, clinical guidelines, PubMed
Supportive and Rehabilitative:
Supportive care (symptom management, pain control, nutrition) > Search first: Clinical guidelines, Cochrane Library, PubMed
Rehabilitation (physical therapy, occupational therapy, speech therapy) > Search first: Rehabilitation medicine databases, clinical guidelines, PubMed
Experimental:
Experimental treatments in clinical trials (with NCT identifiers if available) > Search first: ClinicalTrials.gov, EU Clinical Trials Register, WHO ICTRP
Treatment Outcomes:
Treatment response rates > Search first: Clinical trial databases, FDA reviews, systematic reviews, PubMed
Side effects and adverse events > Search first: FDA Adverse Event Reporting System (FAERS), MedWatch, PubMed
Treatment Strategy:
Treatment algorithms (clinical pathways, decision trees) > Search first: Clinical practice guidelines, NCCN Guidelines, UpToDate
Combination therapies > Search first: ClinicalTrials.gov, treatment guidelines, PubMed
Personalized medicine approaches (genotype-guided treatment) > Search first: My Cancer Genome, CIViC, PharmGKB, precision medicine databases

For each treatment, suggest MAXO (Medical Action Ontology) terms where applicable.

13. Prevention

Prevention Levels:
Primary prevention (preventing disease occurrence: vaccination, risk factor modification) > Search first: CDC, WHO, USPSTF recommendations, Cochrane Library
Secondary prevention (early detection and treatment: screening programs, early intervention) > Search first: USPSTF, CDC screening guidelines, WHO
Tertiary prevention (preventing complications in those with disease) > Search first: Clinical guidelines, disease management protocols, PubMed
Immunization: Vaccine strategies (if applicable)

Search first: CDC vaccine schedules, WHO immunization, FDA vaccine database
Screening and Early Detection:
Screening programs (population-based: newborn screening, cancer screening) > Search first: CDC screening programs, USPSTF, cancer screening databases
Genetic screening (carrier screening, preimplantation genetic diagnosis, prenatal testing) > Search first: ACMG recommendations, ACOG guidelines, GTR
Risk stratification (identifying high-risk individuals for targeted prevention) > Search first: Risk prediction models, clinical calculators, PubMed
Behavioral Interventions: Lifestyle modifications to reduce risk

Search first: CDC, WHO, behavioral intervention databases, Cochrane Library
Counseling: Genetic counseling (risk assessment, family planning guidance)

Search first: NSGC resources, ACMG guidelines, GeneReviews
Public Health:
Public health interventions (sanitation, vector control, health education) > Search first: CDC, WHO, public health databases, PubMed
Environmental interventions (reducing environmental risk factors) > Search first: EPA databases, WHO environmental health, PubMed
Prophylaxis: Preventive medications or procedures

Search first: Clinical guidelines, FDA approvals, PubMed

14. Other Species / Natural Disease

Taxonomy: Species affected (with NCBI Taxon identifiers)

Search first: NCBI Taxonomy
Breed: Specific breeds affected (with VBO identifiers if applicable)

Search first: VBO (Vertebrate Breed Ontology)
Gene: Orthologous genes in other species (with NCBI Gene IDs)

Search first: NCBI Gene
Natural Disease:
Naturally occurring disease in other species (companion animals, wildlife) > Search first: OMIA (Online Mendelian Inheritance in Animals), VetCompass, PubMed
Veterinary relevance and importance in animal health > Search first: OMIA, veterinary databases, PubMed
Comparative Biology:
Comparative pathology (similarities and differences across species) > Search first: OMIA, comparative pathology databases, PubMed
Evolutionary conservation of disease mechanisms > Search first: HomoloGene, OrthoMCL, Alliance of Genome Resources
Transmission (if applicable):
Zoonotic potential > Search first: CDC zoonotic diseases, WHO zoonoses, GIDEON
Cross-species susceptibility > Search first: NCBI Taxonomy, veterinary databases, PubMed

15. Model Organisms

Model Types:
Model organism type (mammalian, invertebrate, cellular, in vitro) > Search first: Alliance of Genome Resources, model organism databases
Specific model systems (mouse, rat, zebrafish, Drosophila, C. elegans, yeast, cell lines, organoids, iPSCs) > Search first: MGI, RGD, ZFIN, FlyBase, WormBase, SGD, ATCC, Cellosaurus
Induced models (drug treatment, surgical intervention, environmental manipulation) > Search first: MGI, model organism databases, PubMed
Genetic Models:
Types available (knockout, knock-in, transgenic, conditional, humanized) > Search first: MGI, IMPC, KOMP, EuMMCR, IMSR
Model Characteristics:
Phenotype recapitulation (how well model reproduces human disease features) > Search first: Model organism databases, comparative studies, PubMed
Model limitations (aspects of human disease not captured) > Search first: Model organism databases, PubMed, review articles
Applications:
Research applications (what aspects of disease can be studied) > Search first: Model organism databases, PubMed
Resources:
Model databases > Search first: MGI, RGD, ZFIN, FlyBase, WormBase, IMSR, EMMA, MMRRC

Citation Requirements

Cite primary literature (PMID preferred) for all mechanistic and clinical claims
Prioritize recent reviews and landmark papers
Include direct quotes from abstracts where possible to support key statements
Distinguish evidence source types: human clinical, model organism, in vitro, computational

Output Format

Structure your response as a comprehensive narrative organized by the sections above. For each section, provide: - Factual content with specific details (numbers, percentages, gene names, variant nomenclature) - Ontology term suggestions (HPO, GO, CL, UBERON, CHEBI, MAXO, MONDO) where applicable - Evidence citations with PMIDs - Direct quotes from abstracts to support key claims - Clear indication when information is not available or not applicable for this disease

This report will be used to populate a disease knowledge base entry with: - Pathophysiology descriptions with causal chains - Gene/protein annotations (HGNC, GO terms) - Phenotype associations (HP terms) with frequencies - Cell type involvement (CL terms) - Anatomical locations (UBERON terms) - Chemical entities (CHEBI terms) - Treatment annotations (MAXO terms) - Evidence items with PMIDs and exact abstract quotes - Epidemiology, prognosis, diagnostic, and prevention information - Animal model descriptions with phenotype recapitulation details

Stevens–Johnson Syndrome (SJS) / Toxic Epidermal Necrolysis (TEN): Comprehensive Disease Characteristics Report (2023–2024 emphasis)

Executive summary

Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are rare, life-threatening, immune-mediated mucocutaneous reactions—most often drug-triggered—characterized by keratinocyte death with epidermal detachment and prominent mucosal involvement. They are best understood as a single disease spectrum defined by the percentage of detached/detachable body surface area (BSA): SJS <10% BSA, SJS/TEN overlap 10–30%, TEN >30%. (hasegawa2024stevens–johnsonsyndromeand pages 1-2, abulatan2023acompilationof pages 1-2)

Recent (2024) multi-omic single-cell studies reinforce that SJS/TEN pathogenesis is dominated by HLA class I–restricted, clonally expanded cytotoxic CD8+ T cells and an inflamed keratinocyte microenvironment; for immune checkpoint inhibitor (ICI)–triggered epidermal necrolysis, macrophage-derived CXCL10–CXCR3 recruitment of cytotoxic T cells and TNF signaling emerge as actionable drivers, with TNF blockade suggested as a targeted strategy. (gibson2024multiomicsinglecellsequencing pages 1-2, chen2024immunecheckpointinhibitorinduced pages 1-2)

1. Disease information

1.1 What is the disease?

SJS/TEN is a dermatologic emergency with epidermal necrosis and detachment plus mucosal erosions. Definitions by detached/detachable BSA are consistent across recent reviews: SJS (<10%), overlap (10–30%), TEN (>30%). (hasegawa2024stevens–johnsonsyndromeand pages 1-2, abulatan2023acompilationof pages 1-2)

Clinical hallmarks emphasized in 2023–2024 sources include fever, painful erythematous rash with blistering and detachment, and mucositis (ocular/oral/genital) with positive Nikolsky sign. (hasegawa2024stevens–johnsonsyndromeand pages 1-2, thong2023druginducedstevensjohnson pages 1-2)

Abstract quote (definition/etiology framing): a 2024 multicenter cohort describes SJS/TEN as “life-threatening acute mucocutaneous disorders usually triggered by drugs.” (erduran2024evaluationofthe pages 1-3)

1.2 Key identifiers (OMIM, Orphanet, ICD-10/11, MeSH, MONDO)

The retrieved corpus did not include ontology identifier tables (MeSH/MONDO/Orphanet/ICD-11) in accessible text; therefore, these cannot be cited from the evidence provided in this run.

Non-evidence supplemental identifiers commonly used in practice (not cited here due to retrieval limits): ICD-10 includes L51.1 (Stevens-Johnson syndrome) and L51.2 (toxic epidermal necrolysis).

1.3 Synonyms / alternative names

Epidermal necrolysis (EN) is commonly used to refer to the spectrum (SJS, overlap, TEN). (erduran2024evaluationofthe pages 1-3)
Lyell syndrome is commonly used for TEN (noted in background and review literature). (abulatan2023acompilationof pages 1-2)

1.4 Evidence source type

The report is derived from aggregated disease-level resources (peer-reviewed reviews, systematic reviews, multicenter cohorts, pharmacovigilance registries, and mechanistic multi-omics studies), not single EHR extractions; individual case reports appear only as supporting context in some review sources.

2. Etiology

2.1 Disease causal factors

Primary cause: drug-triggered immune-mediated cytotoxic reaction is dominant. - A 2023 ophthalmic review estimates medicines account for ~75% of etiologies. (toth2023ophthalmicaspectsof pages 1-2) - Drug-induced SJS/TEN is described as a non-IgE-mediated severe cutaneous adverse reaction with tissue-level cytotoxic T-cell responses. (thong2023druginducedstevensjohnson pages 1-2)

Other triggers described in recent reviews include infections and (more rarely) vaccination. (abulatan2023acompilationof pages 1-2)

2.2 Risk factors

Drug triggers (real-world pharmacovigilance)

A 2024 analysis of the Russian national pharmacovigilance database (2019–2023; n=170 spontaneous reports) found the top suspected drugs were: - lamotrigine 23.5% (n=40) - ibuprofen 12.9% (n=22) - ceftriaxone 8.8% (n=15) - amoxicillin/amoxicillin + beta-lactam inhibitors 8.8% (n=15) - paracetamol 7.6% (n=13) - carbamazepine 5.9% (n=10) (plus azithromycin, valproate, omeprazole, levetiracetam at lower frequencies). (zyryanov2024stevens–johnsonsyndromeand pages 4-5)

Drug classes most often implicated were anti-infectives for systemic use and nervous system agents. (zyryanov2024stevens–johnsonsyndromeand pages 1-2, zyryanov2024stevens–johnsonsyndromeand pages 4-5)

Pharmacogenomic risk factors (gene–drug)

A major determinant of risk is HLA genotype, which shapes drug-antigen presentation and CD8 T-cell activation.

DPWG guideline (Nov 2023; DOI: https://doi.org/10.21203/rs.3.rs-3255043/v1) provides explicit implementation recommendations: - “Carbamazepine should not be used in an HLA-B*15:02 positive patient.” (nijenhuis2023dutchpharmacogeneticsworking pages 1-5) - For HLA-B15:02, HLA-B15:11, or HLA-A31:01 positive patients, DPWG recommends choosing an alternative AED; if unavoidable, advise immediate reporting of rash. (nijenhuis2023dutchpharmacogeneticsworking pages 1-5) - For phenytoin, DPWG considers CYP2C9 genotyping ‘essential’ and recommends maintenance dose reductions with monitoring after 7–10 days. (nijenhuis2023dutchpharmacogeneticsworking pages 1-5) - DPWG phenytoin dose guidance includes reductions to ~70–75% (intermediate metabolizers) and ~40–50% (poor metabolizers), with genotype-specific examples (e.g., 3/*3 ~40%). (nijenhuis2023dutchpharmacogeneticsworking pages 13-16, nijenhuis2023dutchpharmacogeneticsworking pages 16-18)

HLA associations beyond classic AEDs (beta-lactam SCARs): In Thai patients with beta-lactam antibiotic–related SCARs (Frontiers in Pharmacology 2023; DOI https://doi.org/10.3389/fphar.2023.1248386), elevated SJS/TEN risk was reported for multiple alleles, including: - HLA-B*46:02 OR 17.5 (95% CI 1.5–201.6) - HLA-B*57:01 OR 9.5 (95% CI 1.3–71.5) - HLA-DQB1*03:02 OR 7.5 (95% CI 1.8–30.9) - HLA-C*06:02 OR 4.9 (95% CI 1.1–21.4) Protective signal: HLA-A*02:07 OR 0.1 (95% CI 0.0–0.5) (noting multiple associations did not survive Bonferroni correction and require validation). (wattanachai2023associationbetweenhla pages 1-2, wattanachai2023associationbetweenhla pages 6-8)

Demographic/clinical risk signals

In the 2024 multicenter cohort (n=166), diabetes and comorbidities were more common in deceased patients, and positive blood cultures and fever were associated with higher mortality in multivariable modeling. (erduran2024evaluationofthe pages 8-10)

2.3 Protective factors

Genetic protective alleles are not well established broadly, but one study reported HLA-A*02:07 as protective for beta-lactam–related SCARs (OR 0.1). (wattanachai2023associationbetweenhla pages 6-8)

2.4 Gene–environment interactions

SJS/TEN is a paradigmatic gene–environment interaction: exposure to a culprit drug (environment) in a genetically susceptible host (HLA risk allele) drives HLA class I–restricted cytotoxic T-cell responses. This concept is explicit in 2023–2024 expert reviews and single-cell studies. (thong2023druginducedstevensjohnson pages 1-2, gibson2024multiomicsinglecellsequencing pages 1-2)

3. Phenotypes

3.1 Phenotype spectrum and characteristics

Key clinical phenotypes and suggested ontologies are summarized below. Frequencies are included when available.

1) Prodrome / systemic symptoms - Influenza-like illness and fever are common early. (abulatan2023acompilationof pages 1-2) - HPO suggestions: Fever (HP:0001945), Malaise (HP:0033834), Odynophagia (HP:0012531).

2) Cutaneous lesions and epidermal detachment - Painful erythematous rash progressing to bullae and sloughing; positive Nikolsky sign. (hasegawa2024stevens–johnsonsyndromeand pages 1-2, thong2023druginducedstevensjohnson pages 1-2) - HPO: Skin blistering (HP:0008064), Skin erosion (HP:0001070), Epidermal detachment (no single perfect HPO term; may use Skin exfoliation/desquamation—HP:0001009).

3) Mucosal involvement (multisite mucositis) - ≥2 mucosal sites (ocular/oral/genital) emphasized as hallmark; >90% mucosal involvement in drug-induced SJS/TEN is commonly stated in reviews. (thong2023druginducedstevensjohnson pages 1-2, abulatan2023acompilationof pages 1-2) - HPO: Oral ulceration (HP:0000217), Conjunctivitis (HP:0000509), Genital ulceration (HP:0000130).

4) Ocular involvement and sequelae - 2023 ophthalmic review: acute ocular signs in 50–80%; severe early ocular complications ~50%; and ~90% develop chronic ocular disease after the acute phase. (toth2023ophthalmicaspectsof pages 1-2) - HPO: Photophobia (HP:0000613), Dry eye (HP:0001097), Symblepharon (HP:0100789), Corneal opacity (HP:0007957), Blindness (HP:0000618).

3.2 Anatomy affected (organ/tissue/cell)

Primary tissue: epidermis and mucosal epithelia. (hasegawa2024stevens–johnsonsyndromeand pages 1-2)
UBERON suggestions: Skin epidermis (UBERON:0001003), Oral mucosa (UBERON:0000344), Conjunctiva (UBERON:0000970).

Cell types (CL terms; best-effort): - Cytotoxic CD8+ T cells (CL:0000625), keratinocytes (CL:0000312), monocytes (CL:0000576), macrophages (CL:0000235). Mechanistic studies emphasize enriched CD8+ T cells in blister fluid and affected skin. (gibson2024multiomicsinglecellsequencing pages 2-3, chen2024immunecheckpointinhibitorinduced pages 1-2)

4. Genetic / molecular information

4.1 Causal genes

SJS/TEN is generally not a monogenic disorder; it is a complex, drug-triggered immune reaction with strong associations to HLA alleles and other pharmacogenomic markers.

4.2 Pathogenic / susceptibility variants and gene products

Key susceptibility loci include HLA class I alleles (e.g., HLA-B15:02 for carbamazepine) and, in some contexts, class II alleles (e.g., DQB103:02 in beta-lactam SCARs). (nijenhuis2023dutchpharmacogeneticsworking pages 1-5, wattanachai2023associationbetweenhla pages 6-8)

4.3 Molecular mediators and pathways (overview)

Expert reviews summarize that cytotoxic T cells mediate keratinocyte death via granzyme B, perforin, granulysin, IFN-γ, TNF-α, and related pathways. (thong2023druginducedstevensjohnson pages 1-2)

A 2024 review notes epidermal cell death is mediated through Fas–FasL and perforin/granzyme, and adds that necroptosis may also contribute. (hasegawa2024stevens–johnsonsyndromeand pages 1-2)

GO biological process suggestions (best-effort): - T cell mediated cytotoxicity (GO:0001913), regulation of apoptotic process (GO:0042981), necroptotic process (GO:0070266), antigen processing and presentation of peptide antigen via MHC class I (GO:0002474).

5. Environmental information

The main “environmental” exposure is a culprit medication (or, less often, infection/vaccination). Pharmacovigilance and review data support dominant medication triggers. (toth2023ophthalmicaspectsof pages 1-2, zyryanov2024stevens–johnsonsyndromeand pages 4-5)

6. Mechanism / pathophysiology

6.1 Causal chain (drug-triggered SJS/TEN)

Upstream: culprit drug exposure in a susceptible host → drug–HLA presentation → activation/expansion of oligoclonal CD8+ cytotoxic T cells in tissue. (thong2023druginducedstevensjohnson pages 1-2, gibson2024multiomicsinglecellsequencing pages 1-2)

Downstream: cytotoxic effector molecules (granulysin, perforin/granzyme; Fas–FasL; TNF/IFN programs) → keratinocyte death, epidermal necrosis/detachment → barrier loss, fluid loss, infection risk → systemic complications. (hasegawa2024stevens–johnsonsyndromeand pages 1-2, thong2023druginducedstevensjohnson pages 1-2)

6.2 Recent developments (2024 multi-omics / single-cell)

Multiomic single-cell atlas (Nature Communications, Oct 2024; DOI https://doi.org/10.1038/s41467-024-52990-3): - Abstract quote: “SJS/TEN … is a rare but life-threatening cutaneous drug reaction mediated by human leukocyte antigen (HLA) class I-restricted CD8+ T-cells.” (gibson2024multiomicsinglecellsequencing pages 1-2) - Blister fluid is “a rich reservoir of oligoclonal CD8+ T-cells with an effector phenotype” and keratinocytes in affected skin upregulate HLA and interferon-response genes. (gibson2024multiomicsinglecellsequencing pages 1-2) - Quantitatively, blister fluid averaged ~70% CD8+ T cells and affected skin had higher CD8+ T-cell proportion than unaffected skin. (gibson2024multiomicsinglecellsequencing pages 2-3)

ICI-induced epidermal necrolysis mechanism (Nature Communications, accepted Nov 2024; DOI https://doi.org/10.1038/s41467-024-54180-7): - Abstract quote: scRNA-seq “shows overexpression of macrophage-derived CXCL10 that recruits CXCR3+ cytotoxic T lymphocytes (CTL)” and identifies TNF signaling as responsible for macrophage-derived CXCL10 and CTL activation. (chen2024immunecheckpointinhibitorinduced pages 1-2) - The study included “6 cohorts including 25 ICI-induced SJS/TEN patients” (chen2024immunecheckpointinhibitorinduced pages 1-2) - Treatment implication (from abstract): compared with systemic corticosteroids, “patients treated with biologic TNF blockade showed a significantly rapid recovery and no recurrence of SCAR with continuous ICI therapy.” (chen2024immunecheckpointinhibitorinduced pages 1-2)

7. Anatomical structures affected

Skin and mucosa: epidermis, oral mucosa, conjunctiva, genital mucosa. (hasegawa2024stevens–johnsonsyndromeand pages 1-2, thong2023druginducedstevensjohnson pages 1-2)
UBERON suggestions: Skin epidermis (UBERON:0001003), Conjunctiva (UBERON:0000970), Oral mucosa (UBERON:0000344), Genital mucosa (UBERON term depends on site).

8. Temporal development (onset and course)

Drug-triggered SJS/TEN typically occurs after a latency following drug start. - A 2023 review notes a “median of 2 weeks” latency (range 4 days–8 weeks) for drug-induced SJS/TEN. (thong2023druginducedstevensjohnson pages 1-2)

Clinical course features include acute epidermal necrolysis and re-epithelialization over weeks (review synthesis). (abulatan2023acompilationof pages 1-2)

9. Inheritance and population

SJS/TEN is not inherited in a Mendelian fashion; risk is strongly influenced by population HLA allele frequencies and drug exposure.

Population variation is especially important for HLA-B*15:02–associated AED risk, with DPWG highlighting higher prevalence in South/East Asian ancestries and recommending targeted genotyping before specific AEDs in these populations. (nijenhuis2023dutchpharmacogeneticsworking pages 16-18)

10. Diagnostics

10.1 Clinical criteria and classification

BSA thresholds define SJS/overlap/TEN. (hasegawa2024stevens–johnsonsyndromeand pages 1-2, abulatan2023acompilationof pages 1-2)
Hallmarks: fever, ≥2 mucosal involvements, positive Nikolsky sign, epidermal detachment. (thong2023druginducedstevensjohnson pages 1-2)

10.2 Histopathology

SJS/TEN biopsy classically shows full-thickness epidermal necrosis with mononuclear infiltration and dermo-epidermal separation. (chuenwipasakul2023correlationsbetweenhistopathologic pages 1-2)

10.3 Causality assessment (drug attribution)

The ALDEN algorithm is described in a 2023 review as a structured drug causality approach based on time lag, drug presence, (re)challenge, dechallenge, notoriety, and alternatives. (abulatan2023acompilationof pages 9-10)

10.4 Severity and prognosis scoring: SCORTEN

A 2023 review notes: “total SCORTEN ≥5 is associated with 90% mortality.” (thong2023druginducedstevensjohnson pages 1-2)

A 2024 review contains SCORTEN variable tables (risk factors and predicted mortality by score); extracted figure/table evidence is available. (hasegawa2024stevens–johnsonsyndromeand media be19cccd)

11. Outcome / prognosis

11.1 Mortality and complications

Recent multicenter cohort (Turkey; 12 tertiary centers; 2012–2022; n=166; published May 2024; DOI https://doi.org/10.1007/s13555-024-01180-6): - Abstract quote: “Forty (24.1%) of our patients died in hospital.” (erduran2024evaluationofthe pages 10-12) - Mean SCORTEN in first 24h: 2.44 ± 1.42. (erduran2024evaluationofthe pages 1-3) - Strong SCORTEN–mortality association: compared with SCORTEN 0–1, mortality ORs were 12 at SCORTEN 3, 22 at SCORTEN 4, and 84 at SCORTEN 5–6. (erduran2024evaluationofthe pages 8-10) - Complications occurred in 51.8%, including sepsis 14.5%, intubation 13.9%, acute renal failure 12.7%, UTI 11.4%, bacteremia (percentage not fully extractable across excerpts). (erduran2024evaluationofthe pages 10-12)

11.2 Ocular long-term outcomes

Ocular disease is a major morbidity driver; a 2023 narrative review reports chronic ocular disease in ~90% after acute phase. (toth2023ophthalmicaspectsof pages 1-2)

A 2024 SJS surgical series (BMC Ophthalmology; DOI https://doi.org/10.1186/s12886-024-03461-2) reported that corneal sight-rehabilitating surgery improved vision: pre-op VA 1.96 ± 0.43 logMAR to optimal 0.74 ± 0.60 and endpoint 1.06 ± 0.82, mean follow-up 50.6 ± 28.1 months, with 86.7% success rate; 88.9% (8/9) were no longer blind. (peng2024theoutcomesof pages 1-2)

12. Treatment

12.1 Supportive care (cornerstone; real-world implementation)

Modern reviews and cohorts emphasize near-universal supportive care including early withdrawal of the offending drug, ICU/burn-unit level wound and fluid management, infection monitoring, nutrition, and multidisciplinary care. (thong2023druginducedstevensjohnson pages 2-3, erduran2024evaluationofthe pages 1-3)

12.2 Systemic immunomodulatory therapies (evidence and expert interpretation)

Evidence remains limited by rarity and heterogeneous observational designs; authoritative reviews emphasize uncertainty.

A 2023 expert commentary states: “The role of immunomodulatory treatments in SJS/TEN is at present not supported by robust evidence from systematic reviews given the lack of randomized controlled trials.” (thong2023druginducedstevensjohnson pages 1-2)

Real-world usage (2024 multicenter cohort, n=166): - systemic steroids used in 84.3% - IVIG in 49.4% - cyclosporine in 38.6% but “no effect” of systemic steroids/IVIG/cyclosporine on mortality was observed in comparative analyses. (erduran2024evaluationofthe pages 1-3)

12.3 Anti-TNF therapy (emerging targeted strategy)

Mechanistic and clinical evidence increasingly implicates TNF in epidermal necrolysis. - The 2024 ICI-induced SJS/TEN study suggests TNF blockade as a pathway-level intervention and reports faster recovery/no recurrence relative to systemic corticosteroids in that setting. (chen2024immunecheckpointinhibitorinduced pages 1-2)

12.4 Ocular acute interventions (amniotic membrane / ProKera)

A 2023 ophthalmic review states that “Timely amniotic membrane transplantation as a patch combined with conformer, symblepharon ring or ProKera can prevent severe chronic complications.” (toth2023ophthalmicaspectsof pages 1-2)

12.5 MAXO suggestions (best-effort)

Drug withdrawal (MAXO: drug discontinuation)
Intensive supportive care (MAXO: supportive therapy)
Systemic corticosteroid therapy (MAXO)
Intravenous immunoglobulin therapy (MAXO)
Cyclosporine therapy (MAXO)
TNF inhibitor therapy (MAXO)
Amniotic membrane transplantation (MAXO: surgical procedure / tissue transplantation)

(Exact MAXO IDs are not present in retrieved corpus; terms provided for knowledge-base mapping.)

13. Prevention

13.1 Pharmacogenomic prevention (real-world implementation)

Preemptive HLA screening is one of the clearest implementable prevention strategies.

DPWG guidance recommends avoiding carbamazepine in HLA-B*15:02 carriers and considering genotyping as beneficial in higher-prevalence ancestries. (nijenhuis2023dutchpharmacogeneticsworking pages 1-5, nijenhuis2023dutchpharmacogeneticsworking pages 16-18)

A 2023 expert review notes that preventive HLA genotype screening before carbamazepine and allopurinol prescriptions “may further reduce the incidence of SJS/TEN.” (thong2023druginducedstevensjohnson pages 1-2)

14. Other species / natural disease

The retrieved evidence in this run did not provide veterinary/natural disease descriptions across other species.

15. Model organisms / model systems

Recent mechanistic work emphasizes human tissue-based and single-cell approaches. A practical disease-relevant model system is the human skin/blister-fluid cellular ecosystem characterized by multiomic single-cell sequencing. (gibson2024multiomicsinglecellsequencing pages 1-2)

(Additional ex vivo skin explant models are discussed in other retrieved articles but were not fully extracted in this run.)

Key quantitative reference table

Domain	Item	Key data	Source / setting
Definition / diagnostic threshold	Stevens–Johnson syndrome (SJS)	Epidermal detachment <10% body surface area (BSA); part of the SJS/TEN spectrum with extensive mucosal involvement common (hasegawa2024stevens–johnsonsyndromeand pages 1-2, abulatan2023acompilationof pages 1-2, chuenwipasakul2023correlationsbetweenhistopathologic pages 1-2)	Review/clinical summaries (2023–2024)
Definition / diagnostic threshold	SJS/TEN overlap	Epidermal detachment 10–30% BSA (hasegawa2024stevens–johnsonsyndromeand pages 1-2, abulatan2023acompilationof pages 1-2)	Review/clinical summaries (2023–2024)
Definition / diagnostic threshold	Toxic epidermal necrolysis (TEN)	Epidermal detachment >30% BSA (hasegawa2024stevens–johnsonsyndromeand pages 1-2, abulatan2023acompilationof pages 1-2)	Review/clinical summaries (2023–2024)
Epidemiology / mortality	Japan	Incidence about 2.5/million for SJS and 1.0/million for TEN; mortality 4.1% for SJS and 29.9% for TEN (hasegawa2024stevens–johnsonsyndromeand pages 1-2)	Japan-focused review citing national data
Epidemiology / mortality	International review summary	Overall incidence about 2–7/million/year; female:male about 2:1; mortality 10–50%, higher for TEN (abulatan2023acompilationof pages 1-2)	Multi-country review synthesis
Epidemiology / mortality	UK	Incidence 5.76/million/year (abulatan2023acompilationof pages 1-2, toth2023ophthalmicaspectsof pages 1-2)	Review summaries citing UK data
Epidemiology / mortality	France (TEN)	Incidence 1.2–1.3/million/year for TEN (abulatan2023acompilationof pages 1-2)	Review summary citing French data
Epidemiology / mortality	Germany	Incidence 0.93/million (toth2023ophthalmicaspectsof pages 1-2)	Ophthalmic narrative review
Epidemiology / mortality	USA	Incidence 12.35/million (toth2023ophthalmicaspectsof pages 1-2)	Ophthalmic narrative review
Epidemiology / mortality	Europe lethality estimate	Overall lethality 34%; 24% for SJS and 49% for TEN (toth2023ophthalmicaspectsof pages 1-2)	Ophthalmic narrative review
Epidemiology / mortality	Prospective-cohort summary	Reported mortality 5–12.5% for SJS and 25–35% for TEN (gong2023apoa4asa pages 1-2)	Proteomics/prognosis study background
Prognosis tool	SCORTEN high-risk threshold	SCORTEN ≥5 is associated with about 90% mortality (thong2023druginducedstevensjohnson pages 1-2)	Prognostic summary / review
Prognosis tool	SCORTEN in multicenter cohort	In 166 patients, mean day-1 SCORTEN 2.44 ± 1.42; mortality 24.1% (40/166) overall (erduran2024evaluationofthe pages 1-3, erduran2024evaluationofthe pages 10-12, erduran2024evaluationofthe pages 4-6)	Erduran et al. 2024 multicenter study
Prognosis tool	Erduran 2024 ORs by SCORTEN category	Versus SCORTEN 0–1, mortality OR for SCORTEN 3 = 12 (95% CI 2.363–60.948), SCORTEN 4 = 22 (95% CI 4.293–112.740), SCORTEN 5–6 = 84 (95% CI 13.902–507.537); SCORTEN 2 not significant (p=0.38) (erduran2024evaluationofthe pages 8-10)	Erduran et al. 2024 multicenter study
Prognosis tool	Other mortality predictors in Erduran 2024	Fever OR 2.825; positive blood cultures OR 3.664; diabetes mellitus OR 6.273; comorbidity OR 3.326; plasmapheresis associated with about 22-fold higher mortality (95% CI 1.96–247.2) (erduran2024evaluationofthe pages 8-10, erduran2024evaluationofthe pages 10-12)	Erduran et al. 2024 multicenter study

Table: This table condenses the key diagnostic thresholds, representative recent epidemiology and mortality statistics, and the main prognostic information for SJS/TEN, including SCORTEN and the 2024 multicenter mortality odds ratios. It is useful as a quick reference for disease classification and risk stratification.

Notes on evidence limitations (important for knowledge base curation)

1) PMIDs were not consistently available in the retrieved full-text snippets; where absent, the report provides DOI/URL and publication month/year from the papers’ metadata. 2) Ontology IDs (MeSH/MONDO/Orphanet/ICD-11) were not present in the retrieved documents; therefore, identifier fields should be completed by direct lookup in the relevant ontology portals in a subsequent curation step. 3) Several 2023–2024 potentially high-value sources (e.g., formal S3 guidelines; CRISTEN score paper) were listed as “unobtainable” in retrieval and thus could not be cited.

References

(hasegawa2024stevens–johnsonsyndromeand pages 1-2): Akito Hasegawa and Riichiro Abe. Stevens–johnson syndrome and toxic epidermal necrolysis: updates in pathophysiology and management. Chinese Medical Journal, 137:2294-2307, Sep 2024. URL: https://doi.org/10.1097/cm9.0000000000003250, doi:10.1097/cm9.0000000000003250. This article has 34 citations and is from a peer-reviewed journal.
(abulatan2023acompilationof pages 1-2): Isaac T Abulatan, Sage G Ben-David, Lery A Morales-Colon, Elisabeth Beason, and Adegbenro O Fakoya. A compilation of drug etiologies of stevens-johnson syndrome and toxic epidermal necrolysis. Cureus, Nov 2023. URL: https://doi.org/10.7759/cureus.48728, doi:10.7759/cureus.48728. This article has 19 citations.
(gibson2024multiomicsinglecellsequencing pages 1-2): Andrew Gibson, Ramesh Ram, Rama Gangula, Yueran Li, Eric Mukherjee, Amy M. Palubinsky, Chelsea N. Campbell, Michael Thorne, Katherine C. Konvinse, Phuti Choshi, Pooja Deshpande, Sarah Pedretti, Mark W. Fear, Fiona M. Wood, Richard T. O’Neil, Celestine N. Wanjalla, Spyros A. Kalams, Silvana Gaudieri, Rannakoe J. Lehloenya, Samuel S. Bailin, Abha Chopra, Jason A. Trubiano, Jason Trubiano, Jonny G. Peter, Simon A. Mallal, and Elizabeth J. Phillips. Multiomic single-cell sequencing defines tissue-specific responses in stevens-johnson syndrome and toxic epidermal necrolysis. Nature Communications, Oct 2024. URL: https://doi.org/10.1038/s41467-024-52990-3, doi:10.1038/s41467-024-52990-3. This article has 31 citations and is from a highest quality peer-reviewed journal.
(chen2024immunecheckpointinhibitorinduced pages 1-2): Chun-Bing Chen, Shuen-Iu Hung, John Wen-Cheng Chang, Chan-Keng Yang, David Hui-Kang Ma, Yu-Chuan Teng, Chun-Wei Lu, Wei-Ti Chen, Hsiao-Yin Yang, Cheng-Chang Tsai, Chih Liang Wang, Pin-Hsuan Chiang, Jennifer Wu, Ya-Wen Tsai, Lai-Ying Lu, Yang Yu-Wei Lin, Rosaline Chung-Yee Hui, Fu-Mei Hsieh, Chao-Kai Hsu, Chaw-Ning Lee, Yi-Ju Chen, Chih-Chiang Chen, Yilei Cui, Hung-Chih Hsu, Ya-Ching Chang, Chih-Jung Chang, Ho-Chen Lin, Chee Jen Chang, Yu-Jr Lin, Cheng-Lung Ku, Chuang-Wei Wang, and Wen-Hung Chung. Immune checkpoint inhibitor-induced severe epidermal necrolysis mediated by macrophage-derived cxcl10 and abated by tnf blockade. Nature Communications, Dec 2024. URL: https://doi.org/10.1038/s41467-024-54180-7, doi:10.1038/s41467-024-54180-7. This article has 20 citations and is from a highest quality peer-reviewed journal.
(thong2023druginducedstevensjohnson pages 1-2): Bernard Yu-Hor Thong. Drug-induced stevens johnson syndrome and toxic epidermal necrolysis: interpreting the systematic reviews on immunomodulatory therapies. Asia Pacific Allergy, 13:72-76, Jun 2023. URL: https://doi.org/10.5415/apallergy.0000000000000101, doi:10.5415/apallergy.0000000000000101. This article has 14 citations.
(erduran2024evaluationofthe pages 1-3): Funda Erduran, Esra Adışen, Selma Emre, Yıldız Hayran, Emel Bülbül Başkan, Serkan Yazıcı, Aslı Bilgiç, Erkan Alpsoy, Sibel Doğan Günaydın, Leyla Elmas, Melih Akyol, RukiyeYasak Güner, Deniz Aksu Arıca, Yağmur Aypek, Tülin Ergun, Dilan Karavelioğlu, Ayça Cordan Yazıcı, Kübra Aydoğan, Dilek Bayramgürler, Rebiay Kıran, Hilal Kaya Erdoğan, Ersoy Acer, and Akın Aktaş. Evaluation of the factors influencing mortality in patients with stevens-johnson syndrome and toxic epidermal necrolysis: a multicenter study of 166 patients. Dermatology and Therapy, 14:1547-1560, May 2024. URL: https://doi.org/10.1007/s13555-024-01180-6, doi:10.1007/s13555-024-01180-6. This article has 8 citations.
(toth2023ophthalmicaspectsof pages 1-2): Gábor Tóth, Andrea Lukács, Frank Schirra, Gábor L. Sándor, Petra Killik, Otto A. Maneschg, Zoltán Z. Nagy, and Nóra Szentmáry. Ophthalmic aspects of stevens–johnson syndrome and toxic epidermal necrolysis: a narrative review. Ophthalmology and Therapy, 12:1795-1811, May 2023. URL: https://doi.org/10.1007/s40123-023-00725-w, doi:10.1007/s40123-023-00725-w. This article has 38 citations and is from a peer-reviewed journal.
(zyryanov2024stevens–johnsonsyndromeand pages 4-5): Sergey Zyryanov, Irina Asetskaya, Olga Butranova, Elizaveta Terekhina, Vitaly Polivanov, Alexander Yudin, and Kristina Samsonova. Stevens–johnson syndrome and toxic epidermal necrolysis: analysis of the russian database of spontaneous reports. Pharmaceuticals, 17:675, May 2024. URL: https://doi.org/10.3390/ph17060675, doi:10.3390/ph17060675. This article has 11 citations.
(zyryanov2024stevens–johnsonsyndromeand pages 1-2): Sergey Zyryanov, Irina Asetskaya, Olga Butranova, Elizaveta Terekhina, Vitaly Polivanov, Alexander Yudin, and Kristina Samsonova. Stevens–johnson syndrome and toxic epidermal necrolysis: analysis of the russian database of spontaneous reports. Pharmaceuticals, 17:675, May 2024. URL: https://doi.org/10.3390/ph17060675, doi:10.3390/ph17060675. This article has 11 citations.
(nijenhuis2023dutchpharmacogeneticsworking pages 1-5): Marga Nijenhuis, Lisanne Manson, Bianca Soree, Nienke de Boer-Veger, Anne Marie Buunk, Elisa Houwink, Arne Risselada, Gerard Rongen, Ron van Schaik, Jesse Swen, Daniel Touw, Roos van Westrhenen, Vera Deneer, and Henk-Jan Guchelaar. Dutch pharmacogenetics working group (dpwg) guideline for the gene-drug interaction of cyp2c9, hla-a and hla-b with anti-epileptic drugs. Nov 2023. URL: https://doi.org/10.21203/rs.3.rs-3255043/v1, doi:10.21203/rs.3.rs-3255043/v1.
(nijenhuis2023dutchpharmacogeneticsworking pages 13-16): Marga Nijenhuis, Lisanne Manson, Bianca Soree, Nienke de Boer-Veger, Anne Marie Buunk, Elisa Houwink, Arne Risselada, Gerard Rongen, Ron van Schaik, Jesse Swen, Daniel Touw, Roos van Westrhenen, Vera Deneer, and Henk-Jan Guchelaar. Dutch pharmacogenetics working group (dpwg) guideline for the gene-drug interaction of cyp2c9, hla-a and hla-b with anti-epileptic drugs. Nov 2023. URL: https://doi.org/10.21203/rs.3.rs-3255043/v1, doi:10.21203/rs.3.rs-3255043/v1.
(nijenhuis2023dutchpharmacogeneticsworking pages 16-18): Marga Nijenhuis, Lisanne Manson, Bianca Soree, Nienke de Boer-Veger, Anne Marie Buunk, Elisa Houwink, Arne Risselada, Gerard Rongen, Ron van Schaik, Jesse Swen, Daniel Touw, Roos van Westrhenen, Vera Deneer, and Henk-Jan Guchelaar. Dutch pharmacogenetics working group (dpwg) guideline for the gene-drug interaction of cyp2c9, hla-a and hla-b with anti-epileptic drugs. Nov 2023. URL: https://doi.org/10.21203/rs.3.rs-3255043/v1, doi:10.21203/rs.3.rs-3255043/v1.
(wattanachai2023associationbetweenhla pages 1-2): Pansakon Wattanachai, Warayuwadee Amornpinyo, Parinya Konyoung, Danklai Purimart, Usanee Khunarkornsiri, Oranuch Pattanacheewapull, Wichittra Tassaneeyakul, and Nontaya Nakkam. Association between hla alleles and beta-lactam antibiotics-related severe cutaneous adverse reactions. Frontiers in Pharmacology, Sep 2023. URL: https://doi.org/10.3389/fphar.2023.1248386, doi:10.3389/fphar.2023.1248386. This article has 18 citations.
(wattanachai2023associationbetweenhla pages 6-8): Pansakon Wattanachai, Warayuwadee Amornpinyo, Parinya Konyoung, Danklai Purimart, Usanee Khunarkornsiri, Oranuch Pattanacheewapull, Wichittra Tassaneeyakul, and Nontaya Nakkam. Association between hla alleles and beta-lactam antibiotics-related severe cutaneous adverse reactions. Frontiers in Pharmacology, Sep 2023. URL: https://doi.org/10.3389/fphar.2023.1248386, doi:10.3389/fphar.2023.1248386. This article has 18 citations.
(erduran2024evaluationofthe pages 8-10): Funda Erduran, Esra Adışen, Selma Emre, Yıldız Hayran, Emel Bülbül Başkan, Serkan Yazıcı, Aslı Bilgiç, Erkan Alpsoy, Sibel Doğan Günaydın, Leyla Elmas, Melih Akyol, RukiyeYasak Güner, Deniz Aksu Arıca, Yağmur Aypek, Tülin Ergun, Dilan Karavelioğlu, Ayça Cordan Yazıcı, Kübra Aydoğan, Dilek Bayramgürler, Rebiay Kıran, Hilal Kaya Erdoğan, Ersoy Acer, and Akın Aktaş. Evaluation of the factors influencing mortality in patients with stevens-johnson syndrome and toxic epidermal necrolysis: a multicenter study of 166 patients. Dermatology and Therapy, 14:1547-1560, May 2024. URL: https://doi.org/10.1007/s13555-024-01180-6, doi:10.1007/s13555-024-01180-6. This article has 8 citations.
(gibson2024multiomicsinglecellsequencing pages 2-3): Andrew Gibson, Ramesh Ram, Rama Gangula, Yueran Li, Eric Mukherjee, Amy M. Palubinsky, Chelsea N. Campbell, Michael Thorne, Katherine C. Konvinse, Phuti Choshi, Pooja Deshpande, Sarah Pedretti, Mark W. Fear, Fiona M. Wood, Richard T. O’Neil, Celestine N. Wanjalla, Spyros A. Kalams, Silvana Gaudieri, Rannakoe J. Lehloenya, Samuel S. Bailin, Abha Chopra, Jason A. Trubiano, Jason Trubiano, Jonny G. Peter, Simon A. Mallal, and Elizabeth J. Phillips. Multiomic single-cell sequencing defines tissue-specific responses in stevens-johnson syndrome and toxic epidermal necrolysis. Nature Communications, Oct 2024. URL: https://doi.org/10.1038/s41467-024-52990-3, doi:10.1038/s41467-024-52990-3. This article has 31 citations and is from a highest quality peer-reviewed journal.
(chuenwipasakul2023correlationsbetweenhistopathologic pages 1-2): Donlaporn Chuenwipasakul, Chanudda Washrawirul, Rawiphan Panpruk, Jade Wititsuwannakul, Kridipop Charoenchaipiyakul, Supranee Buranapraditkun, Vilavun Puangsricharern, Jettanong Klaewsongkram, and Pawinee Rerknimitr. Correlations between histopathologic findings, serum biomarker levels, and clinical outcomes in stevens–johnson syndrome/toxic epidermal necrolysis (sjs/ten). Scientific Reports, Aug 2023. URL: https://doi.org/10.1038/s41598-023-40812-3, doi:10.1038/s41598-023-40812-3. This article has 17 citations and is from a peer-reviewed journal.
(abulatan2023acompilationof pages 9-10): Isaac T Abulatan, Sage G Ben-David, Lery A Morales-Colon, Elisabeth Beason, and Adegbenro O Fakoya. A compilation of drug etiologies of stevens-johnson syndrome and toxic epidermal necrolysis. Cureus, Nov 2023. URL: https://doi.org/10.7759/cureus.48728, doi:10.7759/cureus.48728. This article has 19 citations.
(hasegawa2024stevens–johnsonsyndromeand media be19cccd): Akito Hasegawa and Riichiro Abe. Stevens–johnson syndrome and toxic epidermal necrolysis: updates in pathophysiology and management. Chinese Medical Journal, 137:2294-2307, Sep 2024. URL: https://doi.org/10.1097/cm9.0000000000003250, doi:10.1097/cm9.0000000000003250. This article has 34 citations and is from a peer-reviewed journal.
(erduran2024evaluationofthe pages 10-12): Funda Erduran, Esra Adışen, Selma Emre, Yıldız Hayran, Emel Bülbül Başkan, Serkan Yazıcı, Aslı Bilgiç, Erkan Alpsoy, Sibel Doğan Günaydın, Leyla Elmas, Melih Akyol, RukiyeYasak Güner, Deniz Aksu Arıca, Yağmur Aypek, Tülin Ergun, Dilan Karavelioğlu, Ayça Cordan Yazıcı, Kübra Aydoğan, Dilek Bayramgürler, Rebiay Kıran, Hilal Kaya Erdoğan, Ersoy Acer, and Akın Aktaş. Evaluation of the factors influencing mortality in patients with stevens-johnson syndrome and toxic epidermal necrolysis: a multicenter study of 166 patients. Dermatology and Therapy, 14:1547-1560, May 2024. URL: https://doi.org/10.1007/s13555-024-01180-6, doi:10.1007/s13555-024-01180-6. This article has 8 citations.
(peng2024theoutcomesof pages 1-2): Rongmei Peng, Miaomiao Chi, Gege Xiao, Hongqiang Qu, Zhan Shen, Yinghan Zhao, and Jing Hong. The outcomes of corneal sight rehabilitating surgery in stevens-johnson syndrome: case series. BMC Ophthalmology, May 2024. URL: https://doi.org/10.1186/s12886-024-03461-2, doi:10.1186/s12886-024-03461-2. This article has 3 citations and is from a peer-reviewed journal.
(thong2023druginducedstevensjohnson pages 2-3): Bernard Yu-Hor Thong. Drug-induced stevens johnson syndrome and toxic epidermal necrolysis: interpreting the systematic reviews on immunomodulatory therapies. Asia Pacific Allergy, 13:72-76, Jun 2023. URL: https://doi.org/10.5415/apallergy.0000000000000101, doi:10.5415/apallergy.0000000000000101. This article has 14 citations.
(gong2023apoa4asa pages 1-2): Ting Gong, Peng Zhang, Shi-Fan Ruan, Zhixun Xiao, Wen Chen, Min Lin, Qingmei Zhong, Renwei Luo, Qiuyun Xu, Jiamei Peng, Bo Cheng, Fa Chen, Lihong Chen, Wen-Hung Chung, and Chao Ji. Apoa4 as a novel predictor of prognosis in stevens-johnson syndrome/toxic epidermal necrolysis: a proteomics analysis from two prospective cohorts. Journal of the American Academy of Dermatology, 89:45-52, Jul 2023. URL: https://doi.org/10.1016/j.jaad.2023.02.058, doi:10.1016/j.jaad.2023.02.058. This article has 15 citations and is from a domain leading peer-reviewed journal.
(erduran2024evaluationofthe pages 4-6): Funda Erduran, Esra Adışen, Selma Emre, Yıldız Hayran, Emel Bülbül Başkan, Serkan Yazıcı, Aslı Bilgiç, Erkan Alpsoy, Sibel Doğan Günaydın, Leyla Elmas, Melih Akyol, RukiyeYasak Güner, Deniz Aksu Arıca, Yağmur Aypek, Tülin Ergun, Dilan Karavelioğlu, Ayça Cordan Yazıcı, Kübra Aydoğan, Dilek Bayramgürler, Rebiay Kıran, Hilal Kaya Erdoğan, Ersoy Acer, and Akın Aktaş. Evaluation of the factors influencing mortality in patients with stevens-johnson syndrome and toxic epidermal necrolysis: a multicenter study of 166 patients. Dermatology and Therapy, 14:1547-1560, May 2024. URL: https://doi.org/10.1007/s13555-024-01180-6, doi:10.1007/s13555-024-01180-6. This article has 8 citations.

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Classifications

Definitions

Subtypes

Pathophysiology

Histopathology

Pathograph

Phenotypes

Genetic Associations

Treatments

Environmental Factors

Biochemical Markers

Source YAML

References & Deep Research

Deep Research

Disease Characteristics Research Template

Target Disease

Research Objectives

1. Disease Information

2. Etiology

3. Phenotypes

4. Genetic/Molecular Information

5. Environmental Information

6. Mechanism / Pathophysiology

7. Anatomical Structures Affected

8. Temporal Development

9. Inheritance and Population

10. Diagnostics

11. Outcome/Prognosis

12. Treatment

13. Prevention

14. Other Species / Natural Disease

15. Model Organisms

Citation Requirements

Output Format

Stevens–Johnson Syndrome (SJS) / Toxic Epidermal Necrolysis (TEN): Comprehensive Disease Characteristics Report (2023–2024 emphasis)

Executive summary

1. Disease information

1.1 What is the disease?

1.2 Key identifiers (OMIM, Orphanet, ICD-10/11, MeSH, MONDO)

1.3 Synonyms / alternative names

1.4 Evidence source type

2. Etiology

2.1 Disease causal factors

2.2 Risk factors

Drug triggers (real-world pharmacovigilance)

Pharmacogenomic risk factors (gene–drug)

Demographic/clinical risk signals

2.3 Protective factors

2.4 Gene–environment interactions

3. Phenotypes

3.1 Phenotype spectrum and characteristics

3.2 Anatomy affected (organ/tissue/cell)

4. Genetic / molecular information

4.1 Causal genes

4.2 Pathogenic / susceptibility variants and gene products

4.3 Molecular mediators and pathways (overview)

5. Environmental information

6. Mechanism / pathophysiology

6.1 Causal chain (drug-triggered SJS/TEN)

6.2 Recent developments (2024 multi-omics / single-cell)

7. Anatomical structures affected

8. Temporal development (onset and course)

9. Inheritance and population

10. Diagnostics

10.1 Clinical criteria and classification

10.2 Histopathology

10.3 Causality assessment (drug attribution)

10.4 Severity and prognosis scoring: SCORTEN

11. Outcome / prognosis

11.1 Mortality and complications

11.2 Ocular long-term outcomes

12. Treatment

12.1 Supportive care (cornerstone; real-world implementation)

12.2 Systemic immunomodulatory therapies (evidence and expert interpretation)

12.3 Anti-TNF therapy (emerging targeted strategy)

12.4 Ocular acute interventions (amniotic membrane / ProKera)

12.5 MAXO suggestions (best-effort)

13. Prevention