Paraneoplastic Pemphigus

Autoimmune MONDO:0018974 Pathograph 15 Show in embeddings browser Pemphigus Autoimmune Bullous Disease Paraneoplastic Syndrome

A highly fatal autoimmune blistering disease arising in patients with an underlying neoplasm, most often a lymphoproliferative disorder. Also called paraneoplastic autoimmune multiorgan syndrome, and the second name is the more accurate one: the disease is not confined to skin. What distinguishes it from the other paraneoplastic autoimmune syndromes is where the antibody comes from. In most of them the immune system mounts a response against a tumour antigen and that response cross-reacts with a host protein. Here, tumour cells of Castleman disease have been shown to secrete antibodies against plakin family proteins directly, and those antibodies detach cultured keratinocytes. The neoplasm is not the provocation for an autoimmune response; it is, at least in that setting, the factory. Two things follow that the entry is built around. Removing the tumour removes the antibody source, which is why tumour control is the first therapeutic move. And it does not reverse bronchiolitis obliterans, the airway complication that drives the mortality - once the small airways have scarred, lung transplantation is often the only option left.

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5
Pathophys.
4
Phenotypes
2
Gaps
15
Pathograph
5
Medical Actions
4
Differentials
2
Models
8
References
1
Deep Research
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Discussions and Knowledge Gaps

2
Which of the many autoantibodies in paraneoplastic pemphigus actually cause the disease, given that the most reliably detected ones are not the demonstrably pathogenic ones?
KNOWLEDGE GAP OPEN gap_which_autoantibody_is_pathogenic
Attached to
pathophysiology#Autoantibody Binding to Desmosomal Plakins and Desmogleins pathophysiology#Desmosome Disruption and Keratinocyte Acantholysis
Patients carry autoantibodies against desmoglein 1 and 3, alpha-2-macroglobulin-like-1, and a long list of plakins - epiplakin, plectin, desmoplakin, bullous pemphigoid antigen 1, envoplakin and periplakin. Detectability and pathogenicity do not line up. Envoplakin and periplakin are almost universally detected by immunoblotting, and their major epitopes have been mapped - yet patient antibodies purified against those two proteins failed to produce any pathological change in animal models. Anti-desmoglein 3 antibodies are demonstrably pathogenic by passive transfer, but a significant proportion of patients have low or absent anti-desmoglein 3, so they cannot be the general explanation. Anti-desmoplakin C-terminus antibodies were shown pathogenic only in 2022, and desmoplakin is the plakin most frequently detected by immunoprecipitation. So the serological profile that defines the disease diagnostically is not the profile that explains it mechanistically, and the entry curates the antibody node without claiming to know which specificity drives which lesion. This matters for treatment: a therapy targeting one specificity would be expected to work only in the subset it explains, and there is currently no way to identify that subset prospectively.
Proposed experiments
Passive transfer of individually purified autoantibody specificities from stratified patient sera
specificity_resolved_passive_transfer_panel
Purify each major specificity separately from sera of patients stratified by anti-desmoglein 3 status, and passively transfer each into the neonatal mouse model with the dose-response and electron-microscopy readouts already validated for desmoplakin. The question is not whether any antibody is pathogenic but which ones account for disease in the anti-desmoglein-3-negative subset.
Show evidence (4 references)
PMID:35911677 SUPPORT Model Organism
"However, patients’ antibodies purified by these two proteins failed to cause any pathological changes in animal models."
The negative result for envoplakin and periplakin, which is the crux of this gap and is easy to miss because it is a negative.
PMID:35911677 SUPPORT Model Organism
"the animal model has demonstrated the pathogenetic role of anti-desmoglein 3 antibodies"
The established half: this specificity is pathogenic by passive transfer. Split from the human-serology half of the same sentence so each item carries one evidence_source.
PMID:35911677 SUPPORT Human Clinical
"it cannot explain the absence or low levels of anti-desmoglein 3 antibodies in a significant portion of PNP patients"
The coverage problem in patients, which is a serological observation rather than a model-organism one.
+ 1 more reference
Why does bronchiolitis obliterans not remit when the neoplasm producing the autoantibodies is controlled?
KNOWLEDGE GAP OPEN gap_irreversible_airway_disease
Attached to
pathophysiology#Bronchiolar Epithelial Injury and Obliterative Airway Scarring treatments#Treatment of the Underlying Neoplasm
This entry's mechanism predicts that removing the tumour should remove the disease, because the tumour is the antibody source. Mucocutaneous disease does behave roughly that way. The airways do not: bronchiolitis obliterans is described as leaving lung transplantation as often the only viable option specifically once the neoplasm has been controlled. The possibilities are not distinguished by anything curated here. The scarring may simply be structurally irreversible once established, in which case the failure is one of timing rather than of mechanism and the implication is that airway disease must be detected earlier. Or the airway lesion may be sustained by a process that outlives the antibody - the cell-mediated arm, or a self-perpetuating fibrotic response of the kind seen in obliterative bronchiolitis after transplantation, which would make it a different disease from the mucocutaneous one sharing a trigger. Nothing in the cited work establishes even that the airway lesion is antibody-mediated at all, which is why the edge to this node is curated with unknown intermediates.
Proposed experiments
Serial physiological and histological airway assessment through tumour control
serial_airway_assessment_after_tumour_control
Follow lung function and, where tissue is available, airway histology in patients from before tumour control through remission, to establish whether early airway disease is reversible and at what point it ceases to be. If early disease remits, the failure is one of detection; if it never remits at any stage, the airway arm is driven by something the antibody does not control.
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Pathophysiology

5
Underlying Neoplasm with Autoantibody Production
The disease requires a neoplasm, benign or malignant, most commonly lymphoproliferative. Castleman disease and non-Hodgkin lymphoma are the two that matter most, and they sit at opposite ends of the prognosis. The mechanistic claim here is stronger than association. Tumour cells from Castleman disease occurring with paraneoplastic pemphigus were shown to secrete antibodies against plakin family proteins, and those antibodies caused detachment of cultured keratinocytes. That makes the tumour an antibody source rather than merely the stimulus for one - which is the mechanistic difference between this disease and the cross-reactivity paraneoplastic syndromes.
Downstream
Autoantibody Binding to Desmosomal Plakins and Desmogleins The antibodies the tumour produces are the ones that bind epithelial adhesion proteins.
Cell-Mediated Interface Mucositis The cellular arm. Curated with unknown intermediates because the sources establish that cell-mediated immunity contributes to pathogenesis and that interface mucositis is seen histologically, without demonstrating the steps from the neoplasm to the T-cell attack.
Show evidence (7 references)
PMID:37597771 SUPPORT Human Clinical
"The condition occurs in patients with underlying benign or malignant neoplasms, most commonly lymphoproliferative disorders."
Establishes the neoplasm as a requirement and names the dominant tumour class.
PMID:35911677 SUPPORT In Vitro
"we investigated the role of the plakin family in PNP and proved that tumor cells of Castleman disease with PNP could secrete antibodies against plakin family proteins and cause detachment of cultured keratinocytes"
The tumour-as-antibody-source claim, which is the specific mechanism this node asserts and the reason it is curated as a trigger rather than a comorbidity.
ORPHA:63455 SUPPORT Other
"generally associated with lymphoma or chronic lymphoid leukemia"
Orphanet's own characterisation of the tumour association. Note that ORPHA:63455 carries a definition and cross-references but no epidemiology or phenotype table, so it contributes nothing to prevalence for this disorder.
+ 4 more references
Autoantibody Binding to Desmosomal Plakins and Desmogleins
Autoantibodies against plakin family proteins are the serological signature of the disease, alongside antibodies against desmoglein 3 and desmoglein 1. Direct immunofluorescence shows IgG and complement deposited both between epithelial cells and along the basement membrane zone - the two-compartment pattern that distinguishes this from pemphigus vulgaris. Which of these antibodies actually does the damage is not settled, and the entry treats that as an open question rather than smoothing it over. See the knowledge gap below.
desmosome GO:0030057 Gene Ontology (GO) Relation: this pathophysiological event involves this cellular component This pathophysiological event involves desmosome (GO:0030057). GO:0030057 is a cellular component from the Gene Ontology.
Animal models
Neonatal mouse passive transfer (anti-envoplakin / anti-periplakin IgG) Mouse fails to recapitulate Purified anti-envoplakin and anti-periplakin patient antibodies produced no pathological change. The model therefore does not support these specificities as pathogenic effectors, while supporting anti-desmoplakin and anti-desmoglein 3 in the same system. This is the structural form of the entry's sharpest open question: the marker that predicts mortality is not the one that reproduces disease. Either it reports on something else that kills, or the model misses how it acts.
Downstream
Desmosome Disruption and Keratinocyte Acantholysis Antibody binding to desmosomal components disrupts the junction.
Show evidence (3 references)
PMID:37597771 SUPPORT Human Clinical
"Both humoral and cell-mediated immunities contribute to the pathogenesis, and autoantibodies against plakin family proteins are characteristic."
Names the plakin autoantibodies as characteristic and, in the same sentence, establishes that the humoral arm is not the whole story.
PMID:41483625 SUPPORT Human Clinical
"Immunofluorescence and serologic studies revealed IgG and complement deposition within intercellular epithelial spaces and along the basement membrane zone, together with circulating anti-plakin antibodies, establishing a diagnosis of paraneoplastic pemphigus."
The deposition pattern in tissue plus the circulating antibody, which together are diagnostic.
PMID:35911677 SUPPORT Human Clinical
"Paraneoplastic pemphigus (PNP) is an autoimmune bullous disease associated with underlying neoplasms and characterized by antibodies against desmoglein 3 (Dsg 3) and plakins."
The two antibody families this node covers.
Desmosome Disruption and Keratinocyte Acantholysis
The rate-limiting lesion, and the one with direct experimental support. Passive transfer of purified anti-desmoplakin C-terminus IgG into neonatal mice produced blisters and acantholysis in a dose-dependent way. Electron microscopy showed what the antibody actually does: keratin intermediate filaments disconnect from the desmosome, so the junction loses its cytoskeletal anchorage rather than being dissolved. Keratinocyte apoptosis followed on TUNEL staining. Anti-desmoglein 3 antibodies from patient sera had already been shown to cause acantholysis in the same model, so at least two distinct autoantibody specificities are independently pathogenic.
keratinocyte CL:0000312 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves keratinocyte (CL:0000312). CL:0000312 is a cell type from the Cell Ontology.
cell-cell adhesion GO:0098609 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased cell-cell adhesion (GO:0098609). GO:0098609 is a biological process from the Gene Ontology. ↓ DECREASED apoptotic process GO:0006915 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased apoptotic process (GO:0006915). GO:0006915 is a biological process from the Gene Ontology. ↑ INCREASED
Animal models
Neonatal mouse passive transfer (anti-desmoplakin C-terminus IgG) Mouse recapitulates Reproduces the node's three curated components - blistering, ultrastructural loss of keratin anchorage, and keratinocyte apoptosis - from purified antibody alone, with a dose-response.
Downstream
Severe Stomatitis Mucosal acantholysis, which is where the disease characteristically begins.
Cutaneous Blistering The same lesion in skin.
Acantholysis The histopathological expression of this node.
Bronchiolar Epithelial Injury and Obliterative Airway Scarring The respiratory arm. Curated with unknown intermediates deliberately: the sources establish that bronchiolitis obliterans is a frequent complication driving mortality, and a lung wedge resection in one case showed bronchiolar scarring, but nothing cited here demonstrates that the airway lesion is produced by the same autoantibodies acting on respiratory epithelium.
Show evidence (4 references)
PMID:35911677 SUPPORT Model Organism
"We found that anti-C terminus of desmoplakin autoantibodies caused blisters and acantholysis in mice skin at a dose-dependent manner."
Passive transfer with a dose-response, which is the strongest form of evidence available for an autoantibody-mediated disease.
PMID:35911677 SUPPORT Model Organism
"The electronic microscopy examination showed the disconnection of keratin intermediate filaments from desmosomes."
The ultrastructural mechanism - loss of cytoskeletal anchorage rather than dissolution of the junction - which is what this node claims.
PMID:35911677 SUPPORT Model Organism
"Lastly, apoptosis of keratinocytes in the TUNEL assay was all detected in the skins of neonatal mice after injection of the anti-C terminus of desmoplakin autoantibodies."
The apoptotic component, which is why this node carries an apoptosis process annotation alongside the adhesion one.
+ 1 more reference
Cell-Mediated Interface Mucositis
The cellular arm, which the humoral account alone does not cover. Biopsies show intraepithelial clefting together with interface mucositis - a lichenoid, T-cell-mediated pattern of injury at the epithelial-stromal junction that antibody deposition does not explain. Its prognostic behaviour is counterintuitive and worth curating for that reason: lichenoid or interface dermatitis is associated with *longer* survival, and remains so in multivariable analysis. A histological pattern that indicates more immune attack predicts a better outcome, which is the kind of finding a purely antibody-centred model of this disease would not anticipate.
Downstream
Severe Stomatitis Interface mucositis is an oral lesion in its own right, and oral involvement is where the disease characteristically starts.
Show evidence (3 references)
PMID:37597771 SUPPORT Human Clinical
"Both humoral and cell-mediated immunities contribute to the pathogenesis, and autoantibodies against plakin family proteins are characteristic."
Establishes the cell-mediated contribution this node models.
PMID:41483625 SUPPORT Human Clinical
"Biopsy of the oral lesions showed intraepithelial clefting and interface mucositis."
The histology, showing the acantholytic and the interface patterns together in the same lesion.
PMID:39426525 SUPPORT Human Clinical
"In the multifactorial Cox proportional hazards regression model, non-Hodgkin lymphoma (hazard ratio, 1.959; 95% CI, 1.286-2.985; P = .002) and lichenoid/interface dermatitis (hazard ratio, 0.555; 95% CI, 0.362-0.850; P = .007) remained associated with the prognosis of PNP/PAMS patients."
The protective association of the interface pattern, surviving multivariable adjustment, which is the counterintuitive finding this node's description flags.
Bronchiolar Epithelial Injury and Obliterative Airway Scarring
The complication that determines survival. Small airways scar and obliterate, producing progressive dyspnoea and respiratory failure. It is curated as a node rather than only as a phenotype because of what it implies for treatment. The scarring is structural and does not reverse when the antibody source is removed, so controlling the neoplasm - which is otherwise the definitive move in this disease - leaves this arm behind. Lung transplantation is often the only option once the tumour is controlled.
Downstream
Bronchiolitis Obliterans The clinical and radiological expression of this node.
Show evidence (3 references)
PMID:37597771 SUPPORT Human Clinical
"Bronchiolitis obliterans (BO) is a frequent complication which contributes to the high mortality rate of PNP/PAMS."
Frequency and mortality contribution, which is what makes this node the prognostically decisive one.
PMID:41483625 SUPPORT Human Clinical
"Wedge resection of the lung showed focal bronchiolar scarring supporting the clinical impression of bronchiolitis obliterans."
Tissue confirmation of the airway lesion, rather than a clinical impression alone.
PMID:41483625 SUPPORT Human Clinical
"Bronchiolitis obliterans, in particular, has been identified as a marker of poor prognosis in patients with PAMS and lung transplantation often represents the only viable treatment option once the underlying neoplasm has been controlled."
The irreversibility claim on which this node's therapeutic significance rests, in the source's own words.
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Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Paraneoplastic Pemphigus Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
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Phenotypes

4
Integument 1
Cutaneous Blistering VERY_FREQUENT Abnormal blistering of the skin HP:0008066 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Abnormal blistering of the skin (HP:0008066). HP:0008066 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:37597771 SUPPORT Human Clinical
"Patients typically present with severe stomatitis and polymorphous skin lesions, which are often resistant to treatment."
The cutaneous half of the presenting picture.
Other 3
Severe Stomatitis VERY_FREQUENT HP:0010280 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Stomatitis (HP:0010280), qualified as severity severe. HP:0010280 is a phenotype from the Human Phenotype Ontology.
Severity: SEVERE
Show evidence (1 reference)
PMID:37597771 SUPPORT Human Clinical
"Patients typically present with severe stomatitis and polymorphous skin lesions, which are often resistant to treatment."
The presenting picture and its treatment resistance. "Typically present" supports the VERY_FREQUENT band for a presenting feature.
Acantholysis HP:0100792 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Acantholysis (HP:0100792). HP:0100792 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:41483625 SUPPORT Human Clinical
"Biopsy of the oral lesions showed intraepithelial clefting and interface mucositis."
The histological finding in a patient, which is what this phenotype records.
Bronchiolitis Obliterans FREQUENT HP:0011946 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Bronchiolitis obliterans (HP:0011946), qualified as course progressive. HP:0011946 is a phenotype from the Human Phenotype Ontology.
Course: PROGRESSIVE
Show evidence (2 references)
PMID:37597771 SUPPORT Human Clinical
"Bronchiolitis obliterans (BO) is a frequent complication which contributes to the high mortality rate of PNP/PAMS."
Direct support for the FREQUENT band ("a frequent complication") and for the mortality significance.
PMID:41483625 SUPPORT Human Clinical
"PAMS often presents as paraneoplastic pemphigus, an autoimmune bullous disease affecting the skin and mucosal surfaces and bronchiolitis obliterans, a small airway disease that can result in respiratory failure and death."
Names the outcome of the airway disease.
💊

Medical Actions

5
Treatment of the Underlying Neoplasm
Action: tumour-directed therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is tumour-directed therapy, annotated with Therapeutic Procedure (NCIT:C49236). NCIT:C49236 is a clinical intervention from the NCI Thesaurus. Ontology label: Therapeutic Procedure NCIT:C49236
The move that follows from the mechanism: if the tumour is producing the autoantibody, removing it removes the source. In the worked Castleman case the paratracheal mass was resected. That reasoning holds much less often than the mechanism suggests, and the entry now says so rather than letting the inference stand. The EADV guideline states that treatment of the underlying neoplasia *rarely* has a favourable impact on the clinical course - while also stating, in a later section, that treating the malignancy is always recommended because it can result in improvement. Those two sentences are in tension within one document, and the reconciliation the guideline implies is anatomical rather than immunological: a *resectable* tumour, such as Castleman disease or thymoma, can be removed outright and remission follows in up to half of such patients, whereas a disseminated haematological malignancy is controlled rather than eliminated and the antibody source persists. So the tumour-as-factory model predicts the outcome of surgery, not the outcome of chemotherapy. The entry curates the distinction because a reader who took the mechanism at face value would over-predict benefit. A second limit is mechanistic in the other direction. Tumour control does not reverse established airway scarring, so even when it works it treats the cause without treating the complication that determines survival.
Mechanism Target:
INHIBITS Underlying Neoplasm with Autoantibody Production — Removes or controls the source of the pathogenic autoantibodies. Acts on the trigger node, which is why it is the only treatment here that is disease-modifying rather than suppressive.
Show evidence (4 references)
PMID:41483625 SUPPORT Human Clinical
"Bronchiolitis obliterans, in particular, has been identified as a marker of poor prognosis in patients with PAMS and lung transplantation often represents the only viable treatment option once the underlying neoplasm has been controlled."
PARTIAL because it establishes tumour control as the expected first step while stating in the same sentence what that step does not achieve.
PMID:36965110 SUPPORT Other
"Despite the strong association with malignancy, treatment of the underlying neoplasia rarely has a favorable impact on the clinical course of PNP/PAMS"
The qualification that keeps this treatment from being read as curative. PARTIAL rather than REFUTE because the same guideline recommends treating the malignancy anyway, and the next quote gives the setting in which it does work.
PMID:36965110 SUPPORT Other
"in patients with an underlying resectable tumor, curative surgery may result in remission in up to half of patients"
The setting in which removing the source does remit the disease, which is what makes the split above anatomical rather than arbitrary.
+ 1 more reference
Rituximab
Action: immunotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is immunotherapy (NCIT:C15262). NCIT:C15262 is a clinical intervention from the NCI Thesaurus. Ontology label: Immunotherapy NCIT:C15262
Agent: rituximab NCIT:C1702 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses rituximab (NCIT:C1702). NCIT:C1702 is a therapeutic agent from the NCI Thesaurus.
Anti-CD20 B-cell depletion, and the treatment whose rationale fits this disease's mechanism most exactly: in lymphoproliferative-associated disease the same drug depletes the neoplastic B cells and the autoreactive ones, which in the tumour-as-factory model are largely the same cells. The guideline calls it the preferred strategy in that setting for precisely this dual action. Split from corticosteroids, which were previously bundled with it. The two act on different things and have different evidence, and the guideline reports a differential organ response for steroids that would be hidden by a combined entry. The overarching caveat is the guideline's own: there is no evidence supporting any specific therapy in this disease, because it is too rare for any to have been tested.
Mechanism Target:
INHIBITS Underlying Neoplasm with Autoantibody Production — The dual action. In B-cell-malignancy-associated disease rituximab depletes the neoplastic compartment that is producing the antibody, so it acts on the trigger node and not only on the antibody it makes.
Show evidence (1 reference)
PMID:36965110 SUPPORT Other
"B-cell depleting therapies such as rituximab represent the preferred strategy by targeting both neoplastic and autoaggressive lymphocytes"
States the dual target explicitly, which is what justifies wiring this drug to the trigger node as well as to the antibody node.
INHIBITS Autoantibody Binding to Desmosomal Plakins and Desmogleins — B-cell depletion reduces production of the pathogenic autoantibodies themselves.
Show evidence (1 reference)
PMID:41483625 SUPPORT Human Clinical
"The patient was treated with steroids and rituximab and recently underwent bilateral lung transplantation due to progressive respiratory symptoms."
Establishes the regimen in use. Note the same sentence records that the respiratory disease progressed regardless.
Show evidence (1 reference)
PMID:36965110 SUPPORT Other
"There is no evidence supporting the use of any specific therapy due to the rarity of the condition"
The guideline's blanket statement about therapy in this disease, curated on the treatment rather than only in notes so the limitation travels with it. PARTIAL because it neither supports nor refutes this drug - it says the question is unanswered.
Systemic Corticosteroids
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: corticosteroid CHEBI:50858 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses corticosteroid (CHEBI:50858). CHEBI:50858 is a therapeutic agent from Chemical Entities of Biological Interest. prednisolone CHEBI:8378 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses prednisolone (CHEBI:8378). CHEBI:8378 is a therapeutic agent from Chemical Entities of Biological Interest.
First-line despite inconsistent responses, and curated separately from rituximab because the guideline reports something a combined entry would hide: steroids usually help the skin, while the mucositis and the bronchiolitis obliterans - the two features that drive morbidity and mortality - may be less responsive. That differential maps onto the pathograph. Steroids act on the arm this entry curates as reversible and not on the arm it curates as irreversible, which is the same shape as the lung transplantation entry below. Prednisolone 0.5 to 1.5 mg/kg/day, usually with a steroid-sparing agent, and at the cost of infection risk in a disease whose commonest cause of death is infection under immunosuppression.
Mechanism Target:
INHIBITS Cell-Mediated Interface Mucositis — Broad suppression of the inflammatory response. Curated as acting on the cell-mediated arm rather than on antibody production, and the guideline's own report that mucositis is among the less responsive features is attached rather than omitted.
Show evidence (1 reference)
PMID:36965110 SUPPORT Other
"Systemic steroids usually have a beneficial effect on cutaneous lesions, while PNP/PAMS-associated mucositis and bronchiolitis obliterans may be less responsive."
PARTIAL, and the reason this treatment is split out: the same sentence supports benefit in skin and reports its absence in the two features that matter most.
Show evidence (1 reference)
PMID:36965110 SUPPORT Other
"systemic corticosteroids still remain the first line of treatment for patients with PNP/PAMS"
Establishes first-line status. PARTIAL because the guideline states it immediately after conceding that responses are inconsistent and may carry life-threatening complications.
Intravenous Immunoglobulin
Action: intravenous immunoglobulin therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is intravenous immunoglobulin therapy (NCIT:C121331). NCIT:C121331 is a clinical intervention from the NCI Thesaurus. Ontology label: Intravenous Immunoglobulin Therapy NCIT:C121331
Curated at the strength the guideline states it, which is low: high doses have "also been employed", with no efficacy claim and no comparison. It is listed here rather than omitted because a reader looking for what has been tried should find it, and because the alternative - leaving it out - would imply it has not been. Deliberately carries no target_mechanisms. IVIG in autoantibody-mediated disease is usually rationalised as accelerating IgG catabolism and blocking Fc receptors, but nothing cited here says which node it acts on in this disease, and inventing an edge would assert a mechanism the sources do not. A peri-operative rationale - giving IVIG around tumour resection to blunt antibody-mediated bronchiolar injury at the moment of tumour lysis - was raised by the deep-research report and is NOT curated. It would bear directly on this entry's second knowledge gap, which is exactly why it needs a primary source; the EADV guideline does not make the claim, and a PubMed search for it did not surface one. Recorded so the lead is not lost.
Show evidence (1 reference)
PMID:36965110 SUPPORT Other
"High doses of intravenous immunoglobulins (IVIG) have also been employed"
PARTIAL because it establishes use and nothing else - no dose comparison, no outcome, no control. That is the whole of what the guideline says about IVIG.
Lung Transplantation
Action: lung transplantationNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is lung transplantation (NCIT:C15274). NCIT:C15274 is a clinical intervention from the NCI Thesaurus. Ontology label: Lung Transplantation NCIT:C15274
The salvage option for established bronchiolitis obliterans, and one that only makes sense once the neoplasm is controlled - transplanting into an uncontrolled antibody source would reproduce the disease in the graft. That it is described as often the only viable option is the clearest statement of this disease's shape: the cause is treatable and one of its consequences is not.
Mechanism Target:
BYPASSES Bronchiolar Epithelial Injury and Obliterative Airway Scarring — Replaces the scarred airways rather than reversing the scarring. Curated as BYPASSES rather than INHIBITS because it does not act on the mechanism at all - it substitutes the organ the mechanism destroyed.
Show evidence (1 reference)
PMID:41483625 SUPPORT Human Clinical
"Bronchiolitis obliterans, in particular, has been identified as a marker of poor prognosis in patients with PAMS and lung transplantation often represents the only viable treatment option once the underlying neoplasm has been controlled."
States both the indication and its precondition, which is why this treatment is curated as acting on the airway node and sequenced after tumour control.
🔬

Biochemical Markers

5
Anti-envoplakin and anti-periplakin autoantibodies (Present in almost all patients by immunoblotting)
Context: The serological hallmark of the disease and the basis of its diagnostic criteria - almost universally detectable by immunoblotting, with epitopes mapped. They are also the sharpest thing in the entry, because two findings about them point in opposite directions. Their presence is independently associated with death in the largest series of haematologic-malignancy-associated cases; and purified patient antibodies against them failed to produce any pathological change in animal models. A marker that predicts mortality without being demonstrably pathogenic is either a reporter of something else or a pathogenic mechanism the models do not capture, and nothing curated here distinguishes those.
Show evidence (3 references)
PMID:35911677 SUPPORT Human Clinical
"especially envoplakin and periplakin (5), which were almost universally detected by immunoblotting (IB)"
Establishes near-universal detectability, and the assay it depends on.
PMID:30981429 SUPPORT Human Clinical
"Multivariate analysis showed that (1) the presence of antienvoplakin antibodies and BO were significantly associated with death"
The prognostic half of the tension described in the context field, from a systematic review of 144 patients and surviving multivariable adjustment.
PMID:35911677 REFUTE Model Organism
"However, patients’ antibodies purified by these two proteins failed to cause any pathological changes in animal models."
REFUTE against pathogenicity, not against the marker. This is the other half of the tension: the antibody that predicts death did nothing when transferred.
Anti-desmoglein 3 autoantibodies (Variably present; absent or low in a significant proportion of patients)
Context: The one specificity whose pathogenic role is established by passive transfer, and the one that cannot serve as the general explanation - it is absent or low in a significant proportion of patients who nonetheless have the disease.
Show evidence (1 reference)
PMID:35911677 SUPPORT Human Clinical
"it cannot explain the absence or low levels of anti-desmoglein 3 antibodies in a significant portion of PNP patients"
The coverage problem, quoted separately from the animal-model half of the same sentence so each evidence item carries a single evidence_source.
Anti-desmoplakin autoantibodies
Context: Most frequently detected by immunoprecipitation. Pathogenicity of the C-terminal specificity was only demonstrated in 2022, by passive transfer with dose-dependent blistering - which is why this entry's central effector node rests on desmoplakin rather than on the more commonly assayed plakins.
Show evidence (1 reference)
PMID:35911677 SUPPORT Human Clinical
"Among the plakin family, DP, most frequently detected by immunoprecipitation (IP), shares high homology with the others"
The assay by which this specificity is usually found, and its homology to the others - which is what makes specificity-resolved passive transfer the experiment the knowledge gap asks for.
Anti-alpha-2-macroglobulin-like protein 1 (A2ML1) autoantibodies
Context: Reported in up to 70% of sera, originally described as the p170 kDa antigen of the classical five-antigen immunoprecipitation complex. Curated because it is the one frequent target that is not a plakin or a cadherin, so a purely desmosomal account of the serology is incomplete.
Show evidence (1 reference)
PMID:36965110 SUPPORT Human Clinical
"Up to 70% of PNP/PAMS sera show reactivity to"
The frequency. The antigen name in the source uses a mathematical minus sign in "α−2-macroglobulin-like protein 1", so the quote stops before it rather than risk a character-level mismatch; the antigen is named in this record's own name field.
Anti-bullous pemphigoid 230 (BP230) autoantibodies
Context: A less frequent target, curated because it is an adverse prognostic factor rather than a diagnostic one - it predicted shorter survival in the 504-patient systematic review. Previously this fact existed only as prose inside a progression note, where nothing could query it.
Show evidence (1 reference)
PMID:39426525 SUPPORT Human Clinical
"it was found that older age, circulating bullous pemphigoid 230 autoantibodies, non-Hodgkin lymphoma, and possible history of causative drugs were associated with shorter survival time"
The prognostic association, as a structured biomarker rather than as free text.
🔬

Diagnosis

3
Consensus diagnostic characteristics (EADV S2k)
There is no validated diagnostic criterion set for this disease, and the guideline that proposes one says so about its own proposal. What most patients share is a combination: severe chronic stomatitis with multi-site mucosal involvement and variable skin lesions, an underlying neoplasm known or later found, a mixed histology, immunoreactant deposits on direct immunofluorescence, rat-bladder reactivity on indirect immunofluorescence, and binding to a variable set of autoantigens. The variability is the point. No single test defines the disease, and the antigen panel is explicitly "a variable set" - which is the diagnostic face of the same problem the knowledge gap below states mechanistically.
Show evidence (3 references)
PMID:36965110 SUPPORT Other
"severe chronic stomatitis with multi-site mucosal involvement accompanied by variable cutaneous lesions"
The first and most constant of the six consensus characteristics.
PMID:36965110 SUPPORT Other
"these criteria have been proposed by consensus agreement among experts, and thereby will require validation by large multicentric prospective investigations in the near future"
PARTIAL, and deliberately curated alongside the criteria rather than after them: the guideline states that its own criteria are unvalidated.
PMID:35911677 SUPPORT Human Clinical
"The criteria we applied included progressive stomatitis, histologic features of acantholysis or lichenoid or interface dermatitis, demonstration of serum antiplakin autoantibodies by immunoblotting or immunoprecipitation, and the presence of an underlying lymphoproliferative neoplasm"
An independent group's applied criteria, which agree with the consensus set on stomatitis, histology, antiplakin serology and the neoplasm - useful because it shows the criteria in operational use rather than only as a proposal.
Indirect immunofluorescence on rat bladder epithelium
The test that most specifically separates this disease from the other pemphigus variants. Rat bladder transitional epithelium expresses plakins but little desmoglein, so a serum that binds it is reporting anti-plakin reactivity rather than the anti-desmoglein reactivity of pemphigus vulgaris.
indirect immunofluorescence on rat bladder epithelium NCIT:C25294 NCI Thesaurus (NCIT)
Results: Positive on rat bladder substrate; titre 1:160 in the flagship case
Show evidence (2 references)
PMID:36965110 SUPPORT Other
"reactivity with rat bladder transitional epithelia by indirect immunofluorescence (IIF) studies"
The consensus characteristic naming the substrate.
PMID:35911677 SUPPORT Human Clinical
"IIF using rat bladder as substrate was also positive and the titer was 1:160"
The test in use, with a titre, in the patient whose serum supplied the passive-transfer experiment this entry's central effector rests on.
Immunoblotting and immunoprecipitation for antiplakin autoantibodies
The assays that identify the antigen panel, and the practical bottleneck in diagnosing this disease - the guideline names their limited availability as one of three reasons diagnosis remains challenging.
immunoblotting and immunoprecipitation for antiplakin autoantibodies NCIT:C25294 NCI Thesaurus (NCIT)
Markers: envoplakin, periplakin, desmoplakin, desmoglein 3, A2ML1
Show evidence (2 references)
PMID:36965110 SUPPORT Other
"the fact that the detection of circulating autoantibodies may require highly specialized tools, such as IB/IP, which are not broadly available"
The availability constraint, which is a fact about diagnosing the disease rather than about the disease.
PMID:37714216 SUPPORT Other
"Evaluating PNP/PAMS requires knowledge of its findings on histopathology, direct immunofluorescence, indirect immunofluorescence, and enzyme-linked immunosorbent assay."
The full modality list, and the one thing the CME review adds that the guideline section above does not name: ELISA alongside the immunoblot and immunoprecipitation assays. No single test defines the disease, which is why this entry curates the workup as a set rather than as a gold standard.
📈

Progression

3
Survival and prognostic determinants
A systematic review of 290 articles covering 504 patients, with survival data on 281, is the largest synthesis available and the source of what is known about prognosis. Older age, circulating bullous pemphigoid 230 autoantibodies, non-Hodgkin lymphoma and a possible history of causative drugs predicted shorter survival; initial oral mucosal involvement, lichenoid or interface dermatitis, Castleman disease and epithelial-derived tumours predicted longer survival. Only two survived multivariable adjustment: non-Hodgkin lymphoma as a hazard, and lichenoid/interface dermatitis as a protective factor. The tumour type is therefore the dominant prognostic variable, which is consistent with the entry's framing of the neoplasm as the driver rather than the setting.
Show evidence (2 references)
PMID:39426525 SUPPORT Human Clinical
"After drawing the Kaplan-Meier survival curves for 281 patients with available survival information, it was found that older age, circulating bullous pemphigoid 230 autoantibodies, non-Hodgkin lymphoma, and possible history of causative drugs were associated with shorter survival time."
The adverse prognostic factors, with the cohort size behind them.
PMID:39426525 SUPPORT Human Clinical
"Initial oral mucosal involvement, lichenoid/interface dermatitis, Castleman disease, and epithelial-derived tumors were associated with longer survival time."
The favourable factors, including the Castleman-versus-lymphoma split this entry's trigger node describes.
Mortality
Three independent estimates, and they do not agree - which is itself the finding, since all three are syntheses of case reports rather than cohorts. The earliest review put mortality at 90% of 33 patients within two years. A French multicentre series of 53 patients gave one-year and five-year overall survival of 49% and 38%. A systematic review restricted to haematologic-malignancy-associated disease (144 patients) gave 57%, with most deaths in the first year. What is consistent across them is the timing rather than the rate: death is concentrated early, and the causes named are infection under immunosuppression, bronchiolitis obliterans-related respiratory failure, and progression of the underlying malignancy - in that order in the French series. So the disease, its treatment and its tumour each kill a share of patients, which is why no single node in the pathograph carries the prognosis.
Show evidence (3 references)
PMID:36965110 SUPPORT Other
"While in a first review by Anhalt et al45, 90% of 33 PNP/PAMS patients died within two years after diagnosis"
The earliest and highest estimate. Tagged OTHER because it is a guideline's citation of a historical review rather than primary data.
PMID:36965110 SUPPORT Human Clinical
"In the latter study, the main cause of death was severe infection due to the immunosuppressive treatment, followed by bronchiolitis obliterans-related respiratory failure and progression of the underlying malignancy"
The ranked causes of death, which is what makes the prognosis multi-causal rather than attributable to one arm of the pathograph.
PMID:30981429 SUPPORT Human Clinical
"The mortality rate was 57%, and most deaths occurred within the first year after the diagnosis of PNP."
The haematologic-malignancy-restricted estimate and the timing, from 144 patients.
Bronchiolitis obliterans as an independent survival factor
The airway arm is not merely a complication that happens to be serious - it survives multivariable adjustment as a determinant of both death and shortened survival, alongside a toxic-epidermal-necrolysis-like and a bullous-pemphigoid-like clinical pattern. This is the quantitative support for the entry's second spine: the consequence that tumour control does not reverse is also the consequence that decides the outcome.
Show evidence (2 references)
PMID:30981429 SUPPORT Human Clinical
"a toxic epidermal necrolysis-like clinical pattern, bullous pemphigoid-like clinical pattern, and BO were significantly associated with decreased survival"
The multivariable result for the airway arm and the two cutaneous patterns.
PMID:30981429 SUPPORT Human Clinical
"The toxic epidermal necrolysis-like and BO-associated forms are independent survival factors in PNP associated with HMs."
The authors' own conclusion, stating independence explicitly.
📊

Prevalence

1
Worldwide
Annual Incidence ≤0.1 per 100,000 <1 in 1,000,000
An upper bound, not a point estimate, and the guideline says so in the preceding sentence: there is little data allowing an estimate at all. Recorded as rate_high only, since "less than one new case per million inhabitants per year" gives a ceiling of 0.1 per 100,000 per year and no lower bound. Note that Orphanet has no epidemiology record for this disorder. ORPHA:63455 carries a definition and cross-references but no prevalence table and no HPO frequency table, so this figure comes from the EADV S2k guideline instead.
Show evidence (2 references)
PMID:36965110 SUPPORT Other
"Based on published reports, one may nevertheless estimate that the incidence of PNP/PAMS is less than one new case per million inhabitants per year."
The figure and its epistemic status - an estimate from published reports, in a consensus guideline rather than a population study. Tagged OTHER for that reason.
PMID:36965110 SUPPORT Other
"It is a very rare disease and there is little data allowing an estimation of its incidence and prevalence"
The guideline's own qualification of the figure above, curated so the limitation travels with the number.
🔀

Differential Diagnoses

4

Conditions with similar clinical presentations that must be differentiated from Paraneoplastic Pemphigus:

Good syndrome
Overlapping Features The closest mimic in the thymoma setting, and the one distinguished by a negative rather than a positive: both direct and indirect immunofluorescence are negative. Curated because a thymoma plus lichenoid oral and cutaneous lesions is otherwise a plausible presentation of this disease.
Distinguishing Features
  • Combined B-cell and T-cell immunodeficiency of adult onset
  • Direct and indirect immunofluorescence both negative, where paraneoplastic pemphigus requires immunoreactant deposition and rat-bladder reactivity
Show evidence (1 reference)
PMID:36965110 SUPPORT Other
"These patients have thymoma and combined B-cell and T-cell immunodeficiency of adult onset and may present with lichenoid oral and cutaneous lesions. Both DIF and IIF are negative in this syndrome."
The presentation and the discriminating test result.
Oral lichen planus
Overlapping Features The mucosal lesions can mimic true oral lichen planus both clinically and histopathologically, in erosive and reticular forms alike - which matters because the lichenoid/interface pattern is simultaneously a favourable prognostic factor in this disease and the feature that makes it look like something else.
Distinguishing Features
  • No underlying neoplasm
  • No antiplakin serology
  • No rat-bladder indirect immunofluorescence reactivity
Show evidence (1 reference)
PMID:36965110 SUPPORT Other
"Mucous membrane lesions of PNP/PAMS may closely mimic “true” oral lichen planus both clinically and histopathologically with both erosive and lichenoid reticular lesions"
The clinical and histological overlap.
Anti-plakin dermatosis
Overlapping Features A reported eruption with envoplakin and periplakin antibodies but negative immunofluorescence and no malignancy, read by the guideline as a variant of relapsing erythema multiforme rather than as this disease. It matters to the entry's central claim: antiplakin antibodies without a tumour do not reproduce the syndrome, which is consistent with the tumour being the source rather than a bystander.
Distinguishing Features
  • Negative immunofluorescence
  • No underlying malignancy
  • Transient rather than chronic course
Show evidence (1 reference)
PMID:36965110 SUPPORT Other
"However, these disorders are usually transient, compared to the chronic course of PNP/PAMS."
The distinguishing course.
Acute cutaneous graft-versus-host disease
Overlapping Features Clinically and pathologically similar, and separated by history and timing rather than by any test. Worth curating because both are immune attacks on stratified epithelium with mucosal and cutaneous involvement.
Distinguishing Features
  • Clinical history and timing after allogeneic haematopoietic stem cell transplantation
Show evidence (1 reference)
PMID:36965110 SUPPORT Other
"GVHD is differentiated from PNP/PAMS on the ground of the clinical history and timing after allogeneic hematopoietic stem cell transplantation"
The basis of the distinction, which is circumstantial rather than serological.
🐁

Animal Models

2
Neonatal mouse passive transfer (anti-desmoplakin C-terminus IgG)
The experiment this entry's central effector rests on. Serum was obtained by plasmapheresis from a 16-year-old patient with paraneoplastic pemphigus, the anti-desmoplakin C-terminus IgG purified from it, and injected into neonatal mice. The donor's tumour was never characterised, and the entry does not claim otherwise. She met the study's inclusion criterion of an underlying lymphoproliferative neoplasm on the strength of a 5 x 4 cm mediastinal mass, and died of sepsis while being prepared for surgery, so no histology was obtained. A mediastinal mass in an adolescent with this disease is suggestive of Castleman disease, but that is an inference, not the reported diagnosis - and the distinction matters here, because this entry's organising thesis is that Castleman tumour cells are the antibody factory. That thesis rests on the group's separate earlier work on Castleman tumour cells, not on this donor. It is also a passive-transfer model rather than a disease model: it reproduces the effector step, not the disease. There is no tumour, no antibody production, and no airway involvement - so it speaks to whether an antibody specificity is pathogenic and to nothing else.
Species
Mouse
Genotype
Wild-type neonatal mouse; passive transfer of patient IgG purified against the desmoplakin C-terminus
Background
Neonatal mice
Publication
PMID:35911677
Pathograph links
Desmosome Disruption and Keratinocyte Acantholysis recapitulates fidelity: high Reproduces the node's three curated components - blistering, ultrastructural loss of keratin anchorage, and keratinocyte apoptosis - from purified antibody alone, with a dose-response.
Limitations: Neonatal mouse skin, a single donor patient, and an effector step isolated from its cause. The model cannot address the airway arm, which is where this disease's mortality sits, and it says nothing about which specificities dominate in unselected patients.
Readouts
Blister formation and acantholysis in skin
Direction: INCREASED
Interpretation: Dose-dependence is what raises this from association to causation for this specificity.
Show evidence (1 reference)
PMID:35911677 SUPPORT Model Organism
"We found that anti-C terminus of desmoplakin autoantibodies caused blisters and acantholysis in mice skin at a dose-dependent manner."
The measurement and its dose-response.
Keratin intermediate filament attachment to desmosomes on electron microscopy
Direction: DECREASED
Interpretation: Identifies the lesion as loss of cytoskeletal anchorage rather than dissolution of the junction itself.
Show evidence (1 reference)
PMID:35911677 SUPPORT Model Organism
"The electronic microscopy examination showed the disconnection of keratin intermediate filaments from desmosomes."
The ultrastructural readout.
Keratinocyte apoptosis by TUNEL assay
Direction: INCREASED
Interpretation: The apoptotic component, which is why the node carries an apoptosis annotation alongside the adhesion one.
Show evidence (1 reference)
PMID:35911677 SUPPORT Model Organism
"Lastly, apoptosis of keratinocytes in the TUNEL assay was all detected in the skins of neonatal mice after injection of the anti-C terminus of desmoplakin autoantibodies."
The apoptosis readout in the same model.
Show evidence (1 reference)
PMID:35911677 SUPPORT Model Organism
"Autoantibodies against desmoglein 3 in sera of patients with PNP have been proven to cause acantholysis in vivo in neonatal mice."
Establishes the model as an accepted assay for this node before this study used it, which is what makes it informative rather than bespoke.
Neonatal mouse passive transfer (anti-envoplakin / anti-periplakin IgG)
The same assay, the same species, a different antibody specificity - and no disease. This is curated as its own model entry rather than as a caveat on the one above because it is a substantive negative claim, and because the specificity that failed here is the one that is almost universally detectable in patients and independently predicts death. A negative result in a model that demonstrably works for other specificities is informative in a way that a negative result in an untested model is not.
Species
Mouse
Genotype
Wild-type neonatal mouse; passive transfer of patient IgG purified against envoplakin and periplakin
Background
Neonatal mice
Publication
PMID:35911677
Pathograph links
Autoantibody Binding to Desmosomal Plakins and Desmogleins fails to recapitulate fidelity: moderate Purified anti-envoplakin and anti-periplakin patient antibodies produced no pathological change. The model therefore does not support these specificities as pathogenic effectors, while supporting anti-desmoplakin and anti-desmoglein 3 in the same system. This is the structural form of the entry's sharpest open question: the marker that predicts mortality is not the one that reproduces disease. Either it reports on something else that kills, or the model misses how it acts.
Limitations: A negative passive-transfer result cannot distinguish a non-pathogenic antibody from one whose pathogenicity requires a cofactor the model lacks - a second specificity, a cell-mediated arm, a target the neonatal mouse does not express in the same form, or a duration longer than the assay. The result constrains the claim; it does not settle it.
Show evidence (1 reference)
PMID:35911677 REFUTE Model Organism
"Still, our previous study failed in observing any phenotype in mouse skin to prove the pathogenesis of antibodies against envoplakin and periplakin."
The negative result, in the source's species-specific phrasing - mouse skin rather than "animal models" - which is what this entry's species assertion actually needs. The broader statement of the same result is curated on the envoplakin/periplakin biomarker record.
{ }

Source YAML

click to show 
name: Paraneoplastic Pemphigus
creation_date: "2026-08-22T04:20:00Z"
category: Autoimmune
disease_term:
  preferred_term: paraneoplastic pemphigus
  term:
    id: MONDO:0018974
    label: paraneoplastic pemphigus
description: >-
  A highly fatal autoimmune blistering disease arising in patients with an underlying
  neoplasm, most often a lymphoproliferative disorder. Also called paraneoplastic
  autoimmune multiorgan syndrome, and the second name is the more accurate one: the
  disease is not confined to skin.

  What distinguishes it from the other paraneoplastic autoimmune syndromes is where the
  antibody comes from. In most of them the immune system mounts a response against a
  tumour antigen and that response cross-reacts with a host protein. Here, tumour cells of
  Castleman disease have been shown to secrete antibodies against plakin family proteins
  directly, and those antibodies detach cultured keratinocytes. The neoplasm is not the
  provocation for an autoimmune response; it is, at least in that setting, the factory.

  Two things follow that the entry is built around. Removing the tumour removes the
  antibody source, which is why tumour control is the first therapeutic move. And it does
  not reverse bronchiolitis obliterans, the airway complication that drives the mortality -
  once the small airways have scarred, lung transplantation is often the only option left.

parents:
- Pemphigus
- Autoimmune Bullous Disease
- Paraneoplastic Syndrome

pathophysiology:

- name: Underlying Neoplasm with Autoantibody Production
  role: trigger
  biological_scale: ORGANISM
  description: >-
    The disease requires a neoplasm, benign or malignant, most commonly lymphoproliferative.
    Castleman disease and non-Hodgkin lymphoma are the two that matter most, and they sit
    at opposite ends of the prognosis.

    The mechanistic claim here is stronger than association. Tumour cells from Castleman
    disease occurring with paraneoplastic pemphigus were shown to secrete antibodies
    against plakin family proteins, and those antibodies caused detachment of cultured
    keratinocytes. That makes the tumour an antibody source rather than merely the stimulus
    for one - which is the mechanistic difference between this disease and the
    cross-reactivity paraneoplastic syndromes.
  evidence:
  - reference: PMID:37597771
    reference_title: "Paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome: Part I. Clinical overview and pathophysiology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The condition occurs in patients with underlying benign or malignant neoplasms, most
      commonly lymphoproliferative disorders.
    explanation: >-
      Establishes the neoplasm as a requirement and names the dominant tumour class.
  - reference: PMID:35911677
    reference_title: "Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      we investigated the role of the plakin family in PNP and proved that tumor cells of
      Castleman disease with PNP could secrete antibodies against plakin family proteins
      and cause detachment of cultured keratinocytes
    explanation: >-
      The tumour-as-antibody-source claim, which is the specific mechanism this node
      asserts and the reason it is curated as a trigger rather than a comorbidity.
  - reference: ORPHA:63455
    reference_title: "Paraneoplastic pemphigus"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      generally associated with lymphoma or chronic lymphoid leukemia
    explanation: >-
      Orphanet's own characterisation of the tumour association. Note that ORPHA:63455
      carries a definition and cross-references but no epidemiology or phenotype table, so
      it contributes nothing to prevalence for this disorder.
  - reference: PMID:36965110
    reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Castleman disease, which has been observed in up to 56% of PNP/PAMS patients, is more
      frequent in Asian countries
    explanation: >-
      The frequency of the tumour type in which the antibody-secretion mechanism was
      demonstrated, plus the geographic variation - which means the flagship mechanistic
      case is drawn from the commonest association in some populations and an uncommon one
      in others.
  - reference: PMID:36965110
    reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Solid tumors have been found in 14.8%−17% of PNP/PAMS patients
    explanation: >-
      The minority of cases in which the tumour is not lymphoproliferative, which bounds
      how far the B-cell-directed treatment rationale extends.
  - reference: PMID:36965110
    reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Few cases of PNP/PAMS have been diagnosed in the absence of an underlying malignancy
    explanation: >-
      PARTIAL, and the reason this node says the disease requires a neoplasm rather than
      that it always has one. The guideline reads these cases as a possible marker of
      occult malignancy requiring extended follow-up rather than as a tumour-free form of
      the disease, but it does not settle that.
  - reference: PMID:41483625
    reference_title: "From the archives of MD Anderson Cancer Center: Paraneoplastic autoimmune multiorgan syndrome (PAMS) associated with stroma-rich Castleman disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Resection of the paratracheal mass revealed lymphoid tissue with follicular and
      interfollicular stromal changes, atretic germinal centers and thickened mantle zones,
      consistent with unicentric Castleman disease, stroma-rich hyaline vascular variant.
    explanation: >-
      A worked case in which the causative neoplasm was identified and resected, with the
      Castleman histology that characterises it.
  downstream:
  - target: Autoantibody Binding to Desmosomal Plakins and Desmogleins
    causal_link_type: DIRECT
    description: >-
      The antibodies the tumour produces are the ones that bind epithelial adhesion
      proteins.
  - target: Cell-Mediated Interface Mucositis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The cellular arm. Curated with unknown intermediates because the sources establish
      that cell-mediated immunity contributes to pathogenesis and that interface mucositis
      is seen histologically, without demonstrating the steps from the neoplasm to the
      T-cell attack.

- name: Autoantibody Binding to Desmosomal Plakins and Desmogleins
  conforms_to: "desmosomal_adhesion_failure#Desmosomal Component Loss or Blockade"
  role: amplifier
  biological_scale: MOLECULAR
  description: >-
    Autoantibodies against plakin family proteins are the serological signature of the
    disease, alongside antibodies against desmoglein 3 and desmoglein 1. Direct
    immunofluorescence shows IgG and complement deposited both between epithelial cells and
    along the basement membrane zone - the two-compartment pattern that distinguishes this
    from pemphigus vulgaris.

    Which of these antibodies actually does the damage is not settled, and the entry treats
    that as an open question rather than smoothing it over. See the knowledge gap below.
  cellular_components:
  - preferred_term: desmosome
    term:
      id: GO:0030057
      label: desmosome
  evidence:
  - reference: PMID:37597771
    reference_title: "Paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome: Part I. Clinical overview and pathophysiology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Both humoral and cell-mediated immunities contribute to the pathogenesis, and
      autoantibodies against plakin family proteins are characteristic.
    explanation: >-
      Names the plakin autoantibodies as characteristic and, in the same sentence,
      establishes that the humoral arm is not the whole story.
  - reference: PMID:41483625
    reference_title: "From the archives of MD Anderson Cancer Center: Paraneoplastic autoimmune multiorgan syndrome (PAMS) associated with stroma-rich Castleman disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Immunofluorescence and serologic studies revealed IgG and complement deposition
      within intercellular epithelial spaces and along the basement membrane zone, together
      with circulating anti-plakin antibodies, establishing a diagnosis of paraneoplastic
      pemphigus.
    explanation: >-
      The deposition pattern in tissue plus the circulating antibody, which together are
      diagnostic.
  - reference: PMID:35911677
    reference_title: "Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Paraneoplastic pemphigus (PNP) is an autoimmune bullous disease associated with
      underlying neoplasms and characterized by antibodies against desmoglein 3 (Dsg 3) and
      plakins.
    explanation: >-
      The two antibody families this node covers.
  downstream:
  - target: Desmosome Disruption and Keratinocyte Acantholysis
    causal_link_type: DIRECT
    description: >-
      Antibody binding to desmosomal components disrupts the junction.

- name: Desmosome Disruption and Keratinocyte Acantholysis
  conforms_to: "desmosomal_adhesion_failure#Acantholysis and Mechanical Failure of Desmosome-Dependent Tissues"
  role: central_effector
  biological_scale: CELLULAR
  description: >-
    The rate-limiting lesion, and the one with direct experimental support. Passive
    transfer of purified anti-desmoplakin C-terminus IgG into neonatal mice produced
    blisters and acantholysis in a dose-dependent way. Electron microscopy showed what the
    antibody actually does: keratin intermediate filaments disconnect from the desmosome,
    so the junction loses its cytoskeletal anchorage rather than being dissolved.
    Keratinocyte apoptosis followed on TUNEL staining.

    Anti-desmoglein 3 antibodies from patient sera had already been shown to cause
    acantholysis in the same model, so at least two distinct autoantibody specificities are
    independently pathogenic.
  cell_types:
  - preferred_term: keratinocyte
    term:
      id: CL:0000312
      label: keratinocyte
  biological_processes:
  - preferred_term: cell-cell adhesion
    term:
      id: GO:0098609
      label: cell-cell adhesion
    modifier: DECREASED
  - preferred_term: apoptotic process
    term:
      id: GO:0006915
      label: apoptotic process
    modifier: INCREASED
  evidence:
  - reference: PMID:35911677
    reference_title: "Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      We found that anti-C terminus of desmoplakin autoantibodies caused blisters and
      acantholysis in mice skin at a dose-dependent manner.
    explanation: >-
      Passive transfer with a dose-response, which is the strongest form of evidence
      available for an autoantibody-mediated disease.
  - reference: PMID:35911677
    reference_title: "Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      The electronic microscopy examination showed the disconnection of keratin
      intermediate filaments from desmosomes.
    explanation: >-
      The ultrastructural mechanism - loss of cytoskeletal anchorage rather than
      dissolution of the junction - which is what this node claims.
  - reference: PMID:35911677
    reference_title: "Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Lastly, apoptosis of keratinocytes in the TUNEL assay was all detected in the skins of
      neonatal mice after injection of the anti-C terminus of desmoplakin autoantibodies.
    explanation: >-
      The apoptotic component, which is why this node carries an apoptosis process
      annotation alongside the adhesion one.
  - reference: PMID:35911677
    reference_title: "Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Autoantibodies against desmoglein 3 in sera of patients with PNP have been proven to
      cause acantholysis in vivo in neonatal mice.
    explanation: >-
      The prior demonstration for a different antibody specificity, establishing that more
      than one is pathogenic.
  downstream:
  - target: Severe Stomatitis
    causal_link_type: DIRECT
    description: >-
      Mucosal acantholysis, which is where the disease characteristically begins.
  - target: Cutaneous Blistering
    causal_link_type: DIRECT
    description: >-
      The same lesion in skin.
  - target: Acantholysis
    causal_link_type: DIRECT
    description: >-
      The histopathological expression of this node.
  - target: Bronchiolar Epithelial Injury and Obliterative Airway Scarring
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The respiratory arm. Curated with unknown intermediates deliberately: the sources
      establish that bronchiolitis obliterans is a frequent complication driving mortality,
      and a lung wedge resection in one case showed bronchiolar scarring, but nothing cited
      here demonstrates that the airway lesion is produced by the same autoantibodies
      acting on respiratory epithelium.

- name: Cell-Mediated Interface Mucositis
  role: amplifier
  biological_scale: TISSUE
  description: >-
    The cellular arm, which the humoral account alone does not cover. Biopsies show
    intraepithelial clefting together with interface mucositis - a lichenoid,
    T-cell-mediated pattern of injury at the epithelial-stromal junction that antibody
    deposition does not explain.

    Its prognostic behaviour is counterintuitive and worth curating for that reason:
    lichenoid or interface dermatitis is associated with *longer* survival, and remains so
    in multivariable analysis. A histological pattern that indicates more immune attack
    predicts a better outcome, which is the kind of finding a purely antibody-centred model
    of this disease would not anticipate.
  evidence:
  - reference: PMID:37597771
    reference_title: "Paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome: Part I. Clinical overview and pathophysiology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Both humoral and cell-mediated immunities contribute to the pathogenesis, and
      autoantibodies against plakin family proteins are characteristic.
    explanation: >-
      Establishes the cell-mediated contribution this node models.
  - reference: PMID:41483625
    reference_title: "From the archives of MD Anderson Cancer Center: Paraneoplastic autoimmune multiorgan syndrome (PAMS) associated with stroma-rich Castleman disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Biopsy of the oral lesions showed intraepithelial clefting and interface mucositis.
    explanation: >-
      The histology, showing the acantholytic and the interface patterns together in the
      same lesion.
  - reference: PMID:39426525
    reference_title: "A systematic review of paraneoplastic pemphigus and paraneoplastic autoimmune multiorgan syndrome: Clinical features and prognostic factors."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In the multifactorial Cox proportional hazards regression model, non-Hodgkin lymphoma
      (hazard ratio, 1.959; 95% CI, 1.286-2.985; P = .002) and lichenoid/interface
      dermatitis (hazard ratio, 0.555; 95% CI, 0.362-0.850; P = .007) remained associated
      with the prognosis of PNP/PAMS patients.
    explanation: >-
      The protective association of the interface pattern, surviving multivariable
      adjustment, which is the counterintuitive finding this node's description flags.
  downstream:
  - target: Severe Stomatitis
    causal_link_type: DIRECT
    description: >-
      Interface mucositis is an oral lesion in its own right, and oral involvement is where
      the disease characteristically starts.

- name: Bronchiolar Epithelial Injury and Obliterative Airway Scarring
  role: consequence
  biological_scale: TISSUE
  description: >-
    The complication that determines survival. Small airways scar and obliterate, producing
    progressive dyspnoea and respiratory failure.

    It is curated as a node rather than only as a phenotype because of what it implies for
    treatment. The scarring is structural and does not reverse when the antibody source is
    removed, so controlling the neoplasm - which is otherwise the definitive move in this
    disease - leaves this arm behind. Lung transplantation is often the only option once
    the tumour is controlled.
  evidence:
  - reference: PMID:37597771
    reference_title: "Paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome: Part I. Clinical overview and pathophysiology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Bronchiolitis obliterans (BO) is a frequent complication which contributes to the high
      mortality rate of PNP/PAMS.
    explanation: >-
      Frequency and mortality contribution, which is what makes this node the prognostically
      decisive one.
  - reference: PMID:41483625
    reference_title: "From the archives of MD Anderson Cancer Center: Paraneoplastic autoimmune multiorgan syndrome (PAMS) associated with stroma-rich Castleman disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Wedge resection of the lung showed focal bronchiolar scarring supporting the clinical
      impression of bronchiolitis obliterans.
    explanation: >-
      Tissue confirmation of the airway lesion, rather than a clinical impression alone.
  - reference: PMID:41483625
    reference_title: "From the archives of MD Anderson Cancer Center: Paraneoplastic autoimmune multiorgan syndrome (PAMS) associated with stroma-rich Castleman disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Bronchiolitis obliterans, in particular, has been identified as a marker of poor
      prognosis in patients with PAMS and lung transplantation often represents the only
      viable treatment option once the underlying neoplasm has been controlled.
    explanation: >-
      The irreversibility claim on which this node's therapeutic significance rests, in the
      source's own words.
  downstream:
  - target: Bronchiolitis Obliterans
    causal_link_type: DIRECT
    description: >-
      The clinical and radiological expression of this node.

phenotypes:

- category: Mucosal
  name: Severe Stomatitis
  description: >-
    Intractable oral mucosal involvement, characteristically the presenting feature and
    often the most treatment-resistant. Initial oral involvement is associated with longer
    survival, probably because it brings patients to attention earlier.
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Stomatitis
    term:
      id: HP:0010280
      label: Stomatitis
    severity: SEVERE
  evidence:
  - reference: PMID:37597771
    reference_title: "Paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome: Part I. Clinical overview and pathophysiology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Patients typically present with severe stomatitis and polymorphous skin lesions, which
      are often resistant to treatment.
    explanation: >-
      The presenting picture and its treatment resistance. "Typically present" supports the
      VERY_FREQUENT band for a presenting feature.

- category: Dermatological
  name: Cutaneous Blistering
  description: >-
    Polymorphous skin lesions - the polymorphism itself is diagnostically important, since
    the eruption can be lichenoid, bullous, or erythema-multiforme-like in the same patient.
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Abnormal blistering of the skin
    term:
      id: HP:0008066
      label: Abnormal blistering of the skin
  evidence:
  - reference: PMID:37597771
    reference_title: "Paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome: Part I. Clinical overview and pathophysiology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Patients typically present with severe stomatitis and polymorphous skin lesions, which
      are often resistant to treatment.
    explanation: >-
      The cutaneous half of the presenting picture.

- category: Histopathological
  name: Acantholysis
  description: >-
    Loss of keratinocyte-keratinocyte adhesion producing intraepithelial clefting, seen on
    biopsy alongside the interface pattern.
  phenotype_term:
    preferred_term: Acantholysis
    term:
      id: HP:0100792
      label: Acantholysis
  evidence:
  - reference: PMID:41483625
    reference_title: "From the archives of MD Anderson Cancer Center: Paraneoplastic autoimmune multiorgan syndrome (PAMS) associated with stroma-rich Castleman disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Biopsy of the oral lesions showed intraepithelial clefting and interface mucositis.
    explanation: >-
      The histological finding in a patient, which is what this phenotype records.

- category: Respiratory
  name: Bronchiolitis Obliterans
  description: >-
    Small airway obliteration causing progressive dyspnoea and respiratory failure. The
    single most prognostically important feature of the disease, and the one that survives
    control of the underlying tumour.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Bronchiolitis obliterans
    term:
      id: HP:0011946
      label: Bronchiolitis obliterans
    clinical_course: PROGRESSIVE
  evidence:
  - reference: PMID:37597771
    reference_title: "Paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome: Part I. Clinical overview and pathophysiology."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Bronchiolitis obliterans (BO) is a frequent complication which contributes to the high
      mortality rate of PNP/PAMS.
    explanation: >-
      Direct support for the FREQUENT band ("a frequent complication") and for the mortality
      significance.
  - reference: PMID:41483625
    reference_title: "From the archives of MD Anderson Cancer Center: Paraneoplastic autoimmune multiorgan syndrome (PAMS) associated with stroma-rich Castleman disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      PAMS often presents as paraneoplastic pemphigus, an autoimmune bullous disease
      affecting the skin and mucosal surfaces and bronchiolitis obliterans, a small airway
      disease that can result in respiratory failure and death.
    explanation: >-
      Names the outcome of the airway disease.

animal_models:

- name: Neonatal mouse passive transfer (anti-desmoplakin C-terminus IgG)
  species: Mouse
  genotype: >-
    Wild-type neonatal mouse; passive transfer of patient IgG purified against the
    desmoplakin C-terminus
  background: Neonatal mice
  publication: PMID:35911677
  description: >-
    The experiment this entry's central effector rests on. Serum was obtained by
    plasmapheresis from a 16-year-old patient with paraneoplastic pemphigus, the
    anti-desmoplakin C-terminus IgG purified from it, and injected into neonatal mice.

    The donor's tumour was never characterised, and the entry does not claim otherwise. She
    met the study's inclusion criterion of an underlying lymphoproliferative neoplasm on the
    strength of a 5 x 4 cm mediastinal mass, and died of sepsis while being prepared for
    surgery, so no histology was obtained. A mediastinal mass in an adolescent with this
    disease is suggestive of Castleman disease, but that is an inference, not the reported
    diagnosis - and the distinction matters here, because this entry's organising thesis is
    that Castleman tumour cells are the antibody factory. That thesis rests on the group's
    separate earlier work on Castleman tumour cells, not on this donor.

    It is also a passive-transfer model rather than a disease model: it reproduces the
    effector step, not the disease. There is no tumour, no antibody production, and no
    airway involvement - so it speaks to whether an antibody specificity is pathogenic and
    to nothing else.
  modeled_mechanisms:
  - target: Desmosome Disruption and Keratinocyte Acantholysis
    relationship: RECAPITULATES
    fidelity: HIGH
    description: >-
      Reproduces the node's three curated components - blistering, ultrastructural loss of
      keratin anchorage, and keratinocyte apoptosis - from purified antibody alone, with a
      dose-response.
    limitations: >-
      Neonatal mouse skin, a single donor patient, and an effector step isolated from its
      cause. The model cannot address the airway arm, which is where this disease's
      mortality sits, and it says nothing about which specificities dominate in unselected
      patients.
    readouts:
    - name: Blister formation and acantholysis in skin
      target: Desmosome Disruption and Keratinocyte Acantholysis
      direction: INCREASED
      interpretation: >-
        Dose-dependence is what raises this from association to causation for this
        specificity.
      evidence:
      - reference: PMID:35911677
        reference_title: "Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          We found that anti-C terminus of desmoplakin autoantibodies caused blisters and
          acantholysis in mice skin at a dose-dependent manner.
        explanation: >-
          The measurement and its dose-response.
    - name: Keratin intermediate filament attachment to desmosomes on electron microscopy
      target: Desmosome Disruption and Keratinocyte Acantholysis
      direction: DECREASED
      interpretation: >-
        Identifies the lesion as loss of cytoskeletal anchorage rather than dissolution of
        the junction itself.
      evidence:
      - reference: PMID:35911677
        reference_title: "Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          The electronic microscopy examination showed the disconnection of keratin
          intermediate filaments from desmosomes.
        explanation: >-
          The ultrastructural readout.
    - name: Keratinocyte apoptosis by TUNEL assay
      target: Desmosome Disruption and Keratinocyte Acantholysis
      direction: INCREASED
      interpretation: >-
        The apoptotic component, which is why the node carries an apoptosis annotation
        alongside the adhesion one.
      evidence:
      - reference: PMID:35911677
        reference_title: "Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          Lastly, apoptosis of keratinocytes in the TUNEL assay was all detected in the skins
          of neonatal mice after injection of the anti-C terminus of desmoplakin
          autoantibodies.
        explanation: >-
          The apoptosis readout in the same model.
    evidence:
    - reference: PMID:35911677
      reference_title: "Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Autoantibodies against desmoglein 3 in sera of patients with PNP have been proven to
        cause acantholysis in vivo in neonatal mice.
      explanation: >-
        Establishes the model as an accepted assay for this node before this study used it,
        which is what makes it informative rather than bespoke.

- name: Neonatal mouse passive transfer (anti-envoplakin / anti-periplakin IgG)
  species: Mouse
  genotype: >-
    Wild-type neonatal mouse; passive transfer of patient IgG purified against envoplakin
    and periplakin
  background: Neonatal mice
  publication: PMID:35911677
  description: >-
    The same assay, the same species, a different antibody specificity - and no disease.

    This is curated as its own model entry rather than as a caveat on the one above because
    it is a substantive negative claim, and because the specificity that failed here is the
    one that is almost universally detectable in patients and independently predicts death.
    A negative result in a model that demonstrably works for other specificities is
    informative in a way that a negative result in an untested model is not.
  modeled_mechanisms:
  - target: Autoantibody Binding to Desmosomal Plakins and Desmogleins
    relationship: FAILS_TO_RECAPITULATE
    fidelity: MODERATE
    description: >-
      Purified anti-envoplakin and anti-periplakin patient antibodies produced no
      pathological change. The model therefore does not support these specificities as
      pathogenic effectors, while supporting anti-desmoplakin and anti-desmoglein 3 in the
      same system.

      This is the structural form of the entry's sharpest open question: the marker that
      predicts mortality is not the one that reproduces disease. Either it reports on
      something else that kills, or the model misses how it acts.
    limitations: >-
      A negative passive-transfer result cannot distinguish a non-pathogenic antibody from
      one whose pathogenicity requires a cofactor the model lacks - a second specificity, a
      cell-mediated arm, a target the neonatal mouse does not express in the same form, or a
      duration longer than the assay. The result constrains the claim; it does not settle
      it.
    evidence:
    - reference: PMID:35911677
      reference_title: "Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo."
      supports: REFUTE
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Still, our previous study failed in observing any phenotype in mouse skin to prove
        the pathogenesis of antibodies against envoplakin and periplakin.
      explanation: >-
        The negative result, in the source's species-specific phrasing - mouse skin rather
        than "animal models" - which is what this entry's species assertion actually needs.
        The broader statement of the same result is curated on the envoplakin/periplakin
        biomarker record.

biochemical:

- name: Anti-envoplakin and anti-periplakin autoantibodies
  context: >-
    The serological hallmark of the disease and the basis of its diagnostic criteria -
    almost universally detectable by immunoblotting, with epitopes mapped.

    They are also the sharpest thing in the entry, because two findings about them point in
    opposite directions. Their presence is independently associated with death in the
    largest series of haematologic-malignancy-associated cases; and purified patient
    antibodies against them failed to produce any pathological change in animal models. A
    marker that predicts mortality without being demonstrably pathogenic is either a
    reporter of something else or a pathogenic mechanism the models do not capture, and
    nothing curated here distinguishes those.
  presence: Present in almost all patients by immunoblotting
  specificity: >-
    Highly specific for paraneoplastic pemphigus among the pemphigus group; anti-plakin
    reactivity is one of the consensus diagnostic characteristics.
  biomarker_term:
    preferred_term: circulating anti-envoplakin and anti-periplakin IgG autoantibodies
  evidence:
  - reference: PMID:35911677
    reference_title: "Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      especially envoplakin and periplakin (5), which were almost universally detected by
      immunoblotting (IB)
    explanation: >-
      Establishes near-universal detectability, and the assay it depends on.
  - reference: PMID:30981429
    reference_title: "Risk factors for death and survival in paraneoplastic pemphigus associated with hematologic malignancies in adults."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Multivariate analysis showed that (1) the presence of antienvoplakin antibodies and BO
      were significantly associated with death
    explanation: >-
      The prognostic half of the tension described in the context field, from a systematic
      review of 144 patients and surviving multivariable adjustment.
  - reference: PMID:35911677
    reference_title: "Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo."
    supports: REFUTE
    evidence_source: MODEL_ORGANISM
    snippet: >-
      However, patients’ antibodies purified by these two proteins failed to cause any
      pathological changes in animal models.
    explanation: >-
      REFUTE against pathogenicity, not against the marker. This is the other half of the
      tension: the antibody that predicts death did nothing when transferred.

- name: Anti-desmoglein 3 autoantibodies
  context: >-
    The one specificity whose pathogenic role is established by passive transfer, and the
    one that cannot serve as the general explanation - it is absent or low in a significant
    proportion of patients who nonetheless have the disease.
  presence: Variably present; absent or low in a significant proportion of patients
  biomarker_term:
    preferred_term: circulating anti-desmoglein 3 IgG autoantibodies
  evidence:
  - reference: PMID:35911677
    reference_title: "Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      it cannot explain the absence or low levels of anti-desmoglein 3 antibodies in a
      significant portion of PNP patients
    explanation: >-
      The coverage problem, quoted separately from the animal-model half of the same
      sentence so each evidence item carries a single evidence_source.

- name: Anti-desmoplakin autoantibodies
  context: >-
    Most frequently detected by immunoprecipitation. Pathogenicity of the C-terminal
    specificity was only demonstrated in 2022, by passive transfer with dose-dependent
    blistering - which is why this entry's central effector node rests on desmoplakin
    rather than on the more commonly assayed plakins.
  biomarker_term:
    preferred_term: circulating anti-desmoplakin IgG autoantibodies
  evidence:
  - reference: PMID:35911677
    reference_title: "Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Among the plakin family, DP, most frequently detected by immunoprecipitation (IP),
      shares high homology with the others
    explanation: >-
      The assay by which this specificity is usually found, and its homology to the others -
      which is what makes specificity-resolved passive transfer the experiment the knowledge
      gap asks for.

- name: Anti-alpha-2-macroglobulin-like protein 1 (A2ML1) autoantibodies
  context: >-
    Reported in up to 70% of sera, originally described as the p170 kDa antigen of the
    classical five-antigen immunoprecipitation complex. Curated because it is the one
    frequent target that is not a plakin or a cadherin, so a purely desmosomal account of
    the serology is incomplete.
  biomarker_term:
    preferred_term: circulating anti-A2ML1 IgG autoantibodies
  evidence:
  - reference: PMID:36965110
    reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Up to 70% of PNP/PAMS sera show reactivity to
    explanation: >-
      The frequency. The antigen name in the source uses a mathematical minus sign in
      "α−2-macroglobulin-like protein 1", so the quote stops before it rather than risk a
      character-level mismatch; the antigen is named in this record's own name field.

- name: Anti-bullous pemphigoid 230 (BP230) autoantibodies
  context: >-
    A less frequent target, curated because it is an adverse prognostic factor rather than
    a diagnostic one - it predicted shorter survival in the 504-patient systematic review.
    Previously this fact existed only as prose inside a progression note, where nothing
    could query it.
  biomarker_term:
    preferred_term: circulating anti-BP230 IgG autoantibodies
  evidence:
  - reference: PMID:39426525
    reference_title: "A systematic review of paraneoplastic pemphigus and paraneoplastic autoimmune multiorgan syndrome: Clinical features and prognostic factors."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      it was found that older age, circulating bullous pemphigoid 230 autoantibodies,
      non-Hodgkin lymphoma, and possible history of causative drugs were associated with
      shorter survival time
    explanation: >-
      The prognostic association, as a structured biomarker rather than as free text.

prevalence:

- population: Worldwide
  measure_type: ANNUAL_INCIDENCE
  prevalence_class: BELOW_1_IN_1000000
  rate_high: 0.1
  notes: >-
    An upper bound, not a point estimate, and the guideline says so in the preceding
    sentence: there is little data allowing an estimate at all. Recorded as rate_high only,
    since "less than one new case per million inhabitants per year" gives a ceiling of 0.1
    per 100,000 per year and no lower bound.

    Note that Orphanet has no epidemiology record for this disorder. ORPHA:63455 carries a
    definition and cross-references but no prevalence table and no HPO frequency table, so
    this figure comes from the EADV S2k guideline instead.
  evidence:
  - reference: PMID:36965110
    reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Based on published reports, one may nevertheless estimate that the incidence of
      PNP/PAMS is less than one new case per million inhabitants per year.
    explanation: >-
      The figure and its epistemic status - an estimate from published reports, in a
      consensus guideline rather than a population study. Tagged OTHER for that reason.
  - reference: PMID:36965110
    reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      It is a very rare disease and there is little data allowing an estimation of its
      incidence and prevalence
    explanation: >-
      The guideline's own qualification of the figure above, curated so the limitation
      travels with the number.

progression:

- phase: Survival and prognostic determinants
  notes: >-
    A systematic review of 290 articles covering 504 patients, with survival data on 281,
    is the largest synthesis available and the source of what is known about prognosis.
    Older age, circulating bullous pemphigoid 230 autoantibodies, non-Hodgkin lymphoma and
    a possible history of causative drugs predicted shorter survival; initial oral mucosal
    involvement, lichenoid or interface dermatitis, Castleman disease and epithelial-derived
    tumours predicted longer survival. Only two survived multivariable adjustment:
    non-Hodgkin lymphoma as a hazard, and lichenoid/interface dermatitis as a protective
    factor.

    The tumour type is therefore the dominant prognostic variable, which is consistent with
    the entry's framing of the neoplasm as the driver rather than the setting.
  evidence:
  - reference: PMID:39426525
    reference_title: "A systematic review of paraneoplastic pemphigus and paraneoplastic autoimmune multiorgan syndrome: Clinical features and prognostic factors."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      After drawing the Kaplan-Meier survival curves for 281 patients with available survival
      information, it was found that older age, circulating bullous pemphigoid 230
      autoantibodies, non-Hodgkin lymphoma, and possible history of causative drugs were
      associated with shorter survival time.
    explanation: >-
      The adverse prognostic factors, with the cohort size behind them.
  - reference: PMID:39426525
    reference_title: "A systematic review of paraneoplastic pemphigus and paraneoplastic autoimmune multiorgan syndrome: Clinical features and prognostic factors."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Initial oral mucosal involvement, lichenoid/interface dermatitis, Castleman disease,
      and epithelial-derived tumors were associated with longer survival time.
    explanation: >-
      The favourable factors, including the Castleman-versus-lymphoma split this entry's
      trigger node describes.

- phase: Mortality
  notes: >-
    Three independent estimates, and they do not agree - which is itself the finding, since
    all three are syntheses of case reports rather than cohorts.

    The earliest review put mortality at 90% of 33 patients within two years. A French
    multicentre series of 53 patients gave one-year and five-year overall survival of 49%
    and 38%. A systematic review restricted to haematologic-malignancy-associated disease
    (144 patients) gave 57%, with most deaths in the first year.

    What is consistent across them is the timing rather than the rate: death is
    concentrated early, and the causes named are infection under immunosuppression,
    bronchiolitis obliterans-related respiratory failure, and progression of the underlying
    malignancy - in that order in the French series. So the disease, its treatment and its
    tumour each kill a share of patients, which is why no single node in the pathograph
    carries the prognosis.
  evidence:
  - reference: PMID:36965110
    reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      While in a first review by Anhalt et al45, 90% of 33 PNP/PAMS patients died within two
      years after diagnosis
    explanation: >-
      The earliest and highest estimate. Tagged OTHER because it is a guideline's citation
      of a historical review rather than primary data.
  - reference: PMID:36965110
    reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In the latter study, the main cause of death was severe infection due to the
      immunosuppressive treatment, followed by bronchiolitis obliterans-related respiratory
      failure and progression of the underlying malignancy
    explanation: >-
      The ranked causes of death, which is what makes the prognosis multi-causal rather
      than attributable to one arm of the pathograph.
  - reference: PMID:30981429
    reference_title: "Risk factors for death and survival in paraneoplastic pemphigus associated with hematologic malignancies in adults."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The mortality rate was 57%, and most deaths occurred within the first year after the
      diagnosis of PNP.
    explanation: >-
      The haematologic-malignancy-restricted estimate and the timing, from 144 patients.

- phase: Bronchiolitis obliterans as an independent survival factor
  notes: >-
    The airway arm is not merely a complication that happens to be serious - it survives
    multivariable adjustment as a determinant of both death and shortened survival,
    alongside a toxic-epidermal-necrolysis-like and a bullous-pemphigoid-like clinical
    pattern.

    This is the quantitative support for the entry's second spine: the consequence that
    tumour control does not reverse is also the consequence that decides the outcome.
  evidence:
  - reference: PMID:30981429
    reference_title: "Risk factors for death and survival in paraneoplastic pemphigus associated with hematologic malignancies in adults."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      a toxic epidermal necrolysis-like clinical pattern, bullous pemphigoid-like clinical
      pattern, and BO were significantly associated with decreased survival
    explanation: >-
      The multivariable result for the airway arm and the two cutaneous patterns.
  - reference: PMID:30981429
    reference_title: "Risk factors for death and survival in paraneoplastic pemphigus associated with hematologic malignancies in adults."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The toxic epidermal necrolysis-like and BO-associated forms are independent survival
      factors in PNP associated with HMs.
    explanation: >-
      The authors' own conclusion, stating independence explicitly.

diagnosis:

- name: Consensus diagnostic characteristics (EADV S2k)
  description: >-
    There is no validated diagnostic criterion set for this disease, and the guideline that
    proposes one says so about its own proposal. What most patients share is a combination:
    severe chronic stomatitis with multi-site mucosal involvement and variable skin lesions,
    an underlying neoplasm known or later found, a mixed histology, immunoreactant deposits
    on direct immunofluorescence, rat-bladder reactivity on indirect immunofluorescence, and
    binding to a variable set of autoantigens.

    The variability is the point. No single test defines the disease, and the antigen panel
    is explicitly "a variable set" - which is the diagnostic face of the same problem the
    knowledge gap below states mechanistically.
  evidence:
  - reference: PMID:36965110
    reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      severe chronic stomatitis with multi-site mucosal involvement accompanied by variable
      cutaneous lesions
    explanation: >-
      The first and most constant of the six consensus characteristics.
  - reference: PMID:36965110
    reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      these criteria have been proposed by consensus agreement among experts, and thereby
      will require validation by large multicentric prospective investigations in the near
      future
    explanation: >-
      PARTIAL, and deliberately curated alongside the criteria rather than after them: the
      guideline states that its own criteria are unvalidated.
  - reference: PMID:35911677
    reference_title: "Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The criteria we applied included progressive stomatitis, histologic features of
      acantholysis or lichenoid or interface dermatitis, demonstration of serum antiplakin
      autoantibodies by immunoblotting or immunoprecipitation, and the presence of an
      underlying lymphoproliferative neoplasm
    explanation: >-
      An independent group's applied criteria, which agree with the consensus set on
      stomatitis, histology, antiplakin serology and the neoplasm - useful because it shows
      the criteria in operational use rather than only as a proposal.

- name: Indirect immunofluorescence on rat bladder epithelium
  description: >-
    The test that most specifically separates this disease from the other pemphigus
    variants. Rat bladder transitional epithelium expresses plakins but little desmoglein,
    so a serum that binds it is reporting anti-plakin reactivity rather than the
    anti-desmoglein reactivity of pemphigus vulgaris.
  diagnosis_term:
    preferred_term: indirect immunofluorescence on rat bladder epithelium
    term:
      id: NCIT:C25294
      label: Laboratory Procedure
  results: Positive on rat bladder substrate; titre 1:160 in the flagship case
  evidence:
  - reference: PMID:36965110
    reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      reactivity with rat bladder transitional epithelia by indirect immunofluorescence
      (IIF) studies
    explanation: >-
      The consensus characteristic naming the substrate.
  - reference: PMID:35911677
    reference_title: "Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      IIF using rat bladder as substrate was also positive and the titer was 1:160
    explanation: >-
      The test in use, with a titre, in the patient whose serum supplied the passive-transfer
      experiment this entry's central effector rests on.

- name: Immunoblotting and immunoprecipitation for antiplakin autoantibodies
  description: >-
    The assays that identify the antigen panel, and the practical bottleneck in diagnosing
    this disease - the guideline names their limited availability as one of three reasons
    diagnosis remains challenging.
  diagnosis_term:
    preferred_term: immunoblotting and immunoprecipitation for antiplakin autoantibodies
    term:
      id: NCIT:C25294
      label: Laboratory Procedure
  markers: envoplakin, periplakin, desmoplakin, desmoglein 3, A2ML1
  evidence:
  - reference: PMID:36965110
    reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      the fact that the detection of circulating autoantibodies may require highly
      specialized tools, such as IB/IP, which are not broadly available
    explanation: >-
      The availability constraint, which is a fact about diagnosing the disease rather than
      about the disease.
  - reference: PMID:37714216
    reference_title: "Paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome: Part II. Diagnosis and management."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Evaluating PNP/PAMS requires knowledge of its findings on histopathology, direct
      immunofluorescence, indirect immunofluorescence, and enzyme-linked immunosorbent
      assay.
    explanation: >-
      The full modality list, and the one thing the CME review adds that the guideline
      section above does not name: ELISA alongside the immunoblot and immunoprecipitation
      assays. No single test defines the disease, which is why this entry curates the
      workup as a set rather than as a gold standard.

differential_diagnoses:

- name: Good syndrome
  description: >-
    The closest mimic in the thymoma setting, and the one distinguished by a negative rather
    than a positive: both direct and indirect immunofluorescence are negative. Curated
    because a thymoma plus lichenoid oral and cutaneous lesions is otherwise a plausible
    presentation of this disease.
  distinguishing_features:
  - Combined B-cell and T-cell immunodeficiency of adult onset
  - Direct and indirect immunofluorescence both negative, where paraneoplastic pemphigus
    requires immunoreactant deposition and rat-bladder reactivity
  evidence:
  - reference: PMID:36965110
    reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      These patients have thymoma and combined B-cell and T-cell immunodeficiency of adult
      onset and may present with lichenoid oral and cutaneous lesions. Both DIF and IIF are
      negative in this syndrome.
    explanation: >-
      The presentation and the discriminating test result.

- name: Oral lichen planus
  description: >-
    The mucosal lesions can mimic true oral lichen planus both clinically and
    histopathologically, in erosive and reticular forms alike - which matters because the
    lichenoid/interface pattern is simultaneously a favourable prognostic factor in this
    disease and the feature that makes it look like something else.
  distinguishing_features:
  - No underlying neoplasm
  - No antiplakin serology
  - No rat-bladder indirect immunofluorescence reactivity
  evidence:
  - reference: PMID:36965110
    reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Mucous membrane lesions of PNP/PAMS may closely mimic “true” oral lichen planus both
      clinically and histopathologically with both erosive and lichenoid reticular lesions
    explanation: >-
      The clinical and histological overlap.

- name: Anti-plakin dermatosis
  description: >-
    A reported eruption with envoplakin and periplakin antibodies but negative
    immunofluorescence and no malignancy, read by the guideline as a variant of relapsing
    erythema multiforme rather than as this disease. It matters to the entry's central
    claim: antiplakin antibodies without a tumour do not reproduce the syndrome, which is
    consistent with the tumour being the source rather than a bystander.
  distinguishing_features:
  - Negative immunofluorescence
  - No underlying malignancy
  - Transient rather than chronic course
  evidence:
  - reference: PMID:36965110
    reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      However, these disorders are usually transient, compared to the chronic course of
      PNP/PAMS.
    explanation: >-
      The distinguishing course.

- name: Acute cutaneous graft-versus-host disease
  description: >-
    Clinically and pathologically similar, and separated by history and timing rather than
    by any test. Worth curating because both are immune attacks on stratified epithelium
    with mucosal and cutaneous involvement.
  distinguishing_features:
  - Clinical history and timing after allogeneic haematopoietic stem cell transplantation
  evidence:
  - reference: PMID:36965110
    reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      GVHD is differentiated from PNP/PAMS on the ground of the clinical history and timing
      after allogeneic hematopoietic stem cell transplantation
    explanation: >-
      The basis of the distinction, which is circumstantial rather than serological.

treatments:

- name: Treatment of the Underlying Neoplasm
  description: >-
    The move that follows from the mechanism: if the tumour is producing the autoantibody,
    removing it removes the source. In the worked Castleman case the paratracheal mass was
    resected.

    That reasoning holds much less often than the mechanism suggests, and the entry now
    says so rather than letting the inference stand. The EADV guideline states that
    treatment of the underlying neoplasia *rarely* has a favourable impact on the clinical
    course - while also stating, in a later section, that treating the malignancy is always
    recommended because it can result in improvement. Those two sentences are in tension
    within one document, and the reconciliation the guideline implies is anatomical rather
    than immunological: a *resectable* tumour, such as Castleman disease or thymoma, can be
    removed outright and remission follows in up to half of such patients, whereas a
    disseminated haematological malignancy is controlled rather than eliminated and the
    antibody source persists.

    So the tumour-as-factory model predicts the outcome of surgery, not the outcome of
    chemotherapy. The entry curates the distinction because a reader who took the mechanism
    at face value would over-predict benefit.

    A second limit is mechanistic in the other direction. Tumour control does not reverse
    established airway scarring, so even when it works it treats the cause without treating
    the complication that determines survival.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: tumour-directed therapy
    term:
      id: NCIT:C49236
      label: Therapeutic Procedure
  target_mechanisms:
  - target: Underlying Neoplasm with Autoantibody Production
    treatment_effect: INHIBITS
    description: >-
      Removes or controls the source of the pathogenic autoantibodies. Acts on the trigger
      node, which is why it is the only treatment here that is disease-modifying rather
      than suppressive.
    evidence:
    - reference: PMID:41483625
      reference_title: "From the archives of MD Anderson Cancer Center: Paraneoplastic autoimmune multiorgan syndrome (PAMS) associated with stroma-rich Castleman disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Bronchiolitis obliterans, in particular, has been identified as a marker of poor
        prognosis in patients with PAMS and lung transplantation often represents the only
        viable treatment option once the underlying neoplasm has been controlled.
      explanation: >-
        PARTIAL because it establishes tumour control as the expected first step while
        stating in the same sentence what that step does not achieve.
    - reference: PMID:36965110
      reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        Despite the strong association with malignancy, treatment of the underlying
        neoplasia rarely has a favorable impact on the clinical course of PNP/PAMS
      explanation: >-
        The qualification that keeps this treatment from being read as curative. PARTIAL
        rather than REFUTE because the same guideline recommends treating the malignancy
        anyway, and the next quote gives the setting in which it does work.
    - reference: PMID:36965110
      reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        in patients with an underlying resectable tumor, curative surgery may result in
        remission in up to half of patients
      explanation: >-
        The setting in which removing the source does remit the disease, which is what
        makes the split above anatomical rather than arbitrary.
    - reference: PMID:36965110
      reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        Early detection and radical resection of tumors such as Castleman’s disease or
        thymoma have occasionally been shown to have a beneficial effect and lead to
        PNP/PAMS resolution
      explanation: >-
        Names the two tumours for which resection is documented to resolve the syndrome -
        including the one in this entry's flagship mechanistic case.

- name: Rituximab
  description: >-
    Anti-CD20 B-cell depletion, and the treatment whose rationale fits this disease's
    mechanism most exactly: in lymphoproliferative-associated disease the same drug depletes
    the neoplastic B cells and the autoreactive ones, which in the tumour-as-factory model
    are largely the same cells. The guideline calls it the preferred strategy in that
    setting for precisely this dual action.

    Split from corticosteroids, which were previously bundled with it. The two act on
    different things and have different evidence, and the guideline reports a differential
    organ response for steroids that would be hidden by a combined entry.

    The overarching caveat is the guideline's own: there is no evidence supporting any
    specific therapy in this disease, because it is too rare for any to have been tested.
  therapeutic_modality: MONOCLONAL_ANTIBODY
  treatment_term:
    preferred_term: immunotherapy
    term:
      id: NCIT:C15262
      label: Immunotherapy
    therapeutic_agent:
    - preferred_term: rituximab
      term:
        id: NCIT:C1702
        label: Rituximab
  target_mechanisms:
  - target: Underlying Neoplasm with Autoantibody Production
    treatment_effect: INHIBITS
    description: >-
      The dual action. In B-cell-malignancy-associated disease rituximab depletes the
      neoplastic compartment that is producing the antibody, so it acts on the trigger node
      and not only on the antibody it makes.
    evidence:
    - reference: PMID:36965110
      reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        B-cell depleting therapies such as rituximab represent the preferred strategy by
        targeting both neoplastic and autoaggressive lymphocytes
      explanation: >-
        States the dual target explicitly, which is what justifies wiring this drug to the
        trigger node as well as to the antibody node.
  - target: Autoantibody Binding to Desmosomal Plakins and Desmogleins
    treatment_effect: INHIBITS
    description: >-
      B-cell depletion reduces production of the pathogenic autoantibodies themselves.
    evidence:
    - reference: PMID:41483625
      reference_title: "From the archives of MD Anderson Cancer Center: Paraneoplastic autoimmune multiorgan syndrome (PAMS) associated with stroma-rich Castleman disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The patient was treated with steroids and rituximab and recently underwent bilateral
        lung transplantation due to progressive respiratory symptoms.
      explanation: >-
        Establishes the regimen in use. Note the same sentence records that the respiratory
        disease progressed regardless.
  evidence:
  - reference: PMID:36965110
    reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      There is no evidence supporting the use of any specific therapy due to the rarity of
      the condition
    explanation: >-
      The guideline's blanket statement about therapy in this disease, curated on the
      treatment rather than only in notes so the limitation travels with it. PARTIAL
      because it neither supports nor refutes this drug - it says the question is
      unanswered.

- name: Systemic Corticosteroids
  description: >-
    First-line despite inconsistent responses, and curated separately from rituximab
    because the guideline reports something a combined entry would hide: steroids usually
    help the skin, while the mucositis and the bronchiolitis obliterans - the two features
    that drive morbidity and mortality - may be less responsive.

    That differential maps onto the pathograph. Steroids act on the arm this entry curates
    as reversible and not on the arm it curates as irreversible, which is the same shape as
    the lung transplantation entry below.

    Prednisolone 0.5 to 1.5 mg/kg/day, usually with a steroid-sparing agent, and at the
    cost of infection risk in a disease whose commonest cause of death is infection under
    immunosuppression.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: corticosteroid
      term:
        id: CHEBI:50858
        label: corticosteroid
    - preferred_term: prednisolone
      term:
        id: CHEBI:8378
        label: prednisolone
  target_mechanisms:
  - target: Cell-Mediated Interface Mucositis
    treatment_effect: INHIBITS
    description: >-
      Broad suppression of the inflammatory response. Curated as acting on the
      cell-mediated arm rather than on antibody production, and the guideline's own report
      that mucositis is among the less responsive features is attached rather than omitted.
    evidence:
    - reference: PMID:36965110
      reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        Systemic steroids usually have a beneficial effect on cutaneous lesions, while
        PNP/PAMS-associated mucositis and bronchiolitis obliterans may be less responsive.
      explanation: >-
        PARTIAL, and the reason this treatment is split out: the same sentence supports
        benefit in skin and reports its absence in the two features that matter most.
  evidence:
  - reference: PMID:36965110
    reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      systemic corticosteroids still remain the first line of treatment for patients with
      PNP/PAMS
    explanation: >-
      Establishes first-line status. PARTIAL because the guideline states it immediately
      after conceding that responses are inconsistent and may carry life-threatening
      complications.

- name: Intravenous Immunoglobulin
  description: >-
    Curated at the strength the guideline states it, which is low: high doses have "also
    been employed", with no efficacy claim and no comparison. It is listed here rather than
    omitted because a reader looking for what has been tried should find it, and because
    the alternative - leaving it out - would imply it has not been.

    Deliberately carries no target_mechanisms. IVIG in autoantibody-mediated disease is
    usually rationalised as accelerating IgG catabolism and blocking Fc receptors, but
    nothing cited here says which node it acts on in this disease, and inventing an edge
    would assert a mechanism the sources do not.

    A peri-operative rationale - giving IVIG around tumour resection to blunt
    antibody-mediated bronchiolar injury at the moment of tumour lysis - was raised by the
    deep-research report and is NOT curated. It would bear directly on this entry's second
    knowledge gap, which is exactly why it needs a primary source; the EADV guideline does
    not make the claim, and a PubMed search for it did not surface one. Recorded so the
    lead is not lost.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: intravenous immunoglobulin therapy
    term:
      id: NCIT:C121331
      label: Intravenous Immunoglobulin Therapy
  evidence:
  - reference: PMID:36965110
    reference_title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      High doses of intravenous immunoglobulins (IVIG) have also been employed
    explanation: >-
      PARTIAL because it establishes use and nothing else - no dose comparison, no outcome,
      no control. That is the whole of what the guideline says about IVIG.

- name: Lung Transplantation
  description: >-
    The salvage option for established bronchiolitis obliterans, and one that only makes
    sense once the neoplasm is controlled - transplanting into an uncontrolled antibody
    source would reproduce the disease in the graft.

    That it is described as often the only viable option is the clearest statement of this
    disease's shape: the cause is treatable and one of its consequences is not.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: lung transplantation
    term:
      id: NCIT:C15274
      label: Lung Transplantation
  target_mechanisms:
  - target: Bronchiolar Epithelial Injury and Obliterative Airway Scarring
    treatment_effect: BYPASSES
    description: >-
      Replaces the scarred airways rather than reversing the scarring. Curated as BYPASSES
      rather than INHIBITS because it does not act on the mechanism at all - it substitutes
      the organ the mechanism destroyed.
    evidence:
    - reference: PMID:41483625
      reference_title: "From the archives of MD Anderson Cancer Center: Paraneoplastic autoimmune multiorgan syndrome (PAMS) associated with stroma-rich Castleman disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Bronchiolitis obliterans, in particular, has been identified as a marker of poor
        prognosis in patients with PAMS and lung transplantation often represents the only
        viable treatment option once the underlying neoplasm has been controlled.
      explanation: >-
        States both the indication and its precondition, which is why this treatment is
        curated as acting on the airway node and sequenced after tumour control.

discussions:

- discussion_id: gap_which_autoantibody_is_pathogenic
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    Which of the many autoantibodies in paraneoplastic pemphigus actually cause the
    disease, given that the most reliably detected ones are not the demonstrably pathogenic
    ones?
  attaches_to:
  - pathophysiology#Autoantibody Binding to Desmosomal Plakins and Desmogleins
  - pathophysiology#Desmosome Disruption and Keratinocyte Acantholysis
  rationale: >-
    Patients carry autoantibodies against desmoglein 1 and 3, alpha-2-macroglobulin-like-1,
    and a long list of plakins - epiplakin, plectin, desmoplakin, bullous pemphigoid antigen
    1, envoplakin and periplakin. Detectability and pathogenicity do not line up.

    Envoplakin and periplakin are almost universally detected by immunoblotting, and their
    major epitopes have been mapped - yet patient antibodies purified against those two
    proteins failed to produce any pathological change in animal models. Anti-desmoglein 3
    antibodies are demonstrably pathogenic by passive transfer, but a significant proportion
    of patients have low or absent anti-desmoglein 3, so they cannot be the general
    explanation. Anti-desmoplakin C-terminus antibodies were shown pathogenic only in 2022,
    and desmoplakin is the plakin most frequently detected by immunoprecipitation.

    So the serological profile that defines the disease diagnostically is not the profile
    that explains it mechanistically, and the entry curates the antibody node without
    claiming to know which specificity drives which lesion. This matters for treatment: a
    therapy targeting one specificity would be expected to work only in the subset it
    explains, and there is currently no way to identify that subset prospectively.
  evidence:
  - reference: PMID:35911677
    reference_title: "Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      However, patients’ antibodies purified by these two proteins failed to cause any
      pathological changes in animal models.
    explanation: >-
      The negative result for envoplakin and periplakin, which is the crux of this gap and
      is easy to miss because it is a negative.
  - reference: PMID:35911677
    reference_title: "Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      the animal model has demonstrated the pathogenetic role of anti-desmoglein 3
      antibodies
    explanation: >-
      The established half: this specificity is pathogenic by passive transfer. Split from
      the human-serology half of the same sentence so each item carries one evidence_source.
  - reference: PMID:35911677
    reference_title: "Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      it cannot explain the absence or low levels of anti-desmoglein 3 antibodies in a
      significant portion of PNP patients
    explanation: >-
      The coverage problem in patients, which is a serological observation rather than a
      model-organism one.
  - reference: PMID:30981429
    reference_title: "Risk factors for death and survival in paraneoplastic pemphigus associated with hematologic malignancies in adults."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Multivariate analysis showed that (1) the presence of antienvoplakin antibodies and BO
      were significantly associated with death
    explanation: >-
      Sharpens the gap rather than narrowing it. The specificity that is almost universally
      present and independently predicts death is the same one whose purified antibodies did
      nothing in animal models. Either it reports something else that kills, or the models
      miss how it acts.
  proposed_experiments:
  - experiment_id: specificity_resolved_passive_transfer_panel
    name: Passive transfer of individually purified autoantibody specificities from stratified patient sera
    description: >-
      Purify each major specificity separately from sera of patients stratified by
      anti-desmoglein 3 status, and passively transfer each into the neonatal mouse model
      with the dose-response and electron-microscopy readouts already validated for
      desmoplakin. The question is not whether any antibody is pathogenic but which ones
      account for disease in the anti-desmoglein-3-negative subset.

- discussion_id: gap_irreversible_airway_disease
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    Why does bronchiolitis obliterans not remit when the neoplasm producing the
    autoantibodies is controlled?
  attaches_to:
  - pathophysiology#Bronchiolar Epithelial Injury and Obliterative Airway Scarring
  - treatments#Treatment of the Underlying Neoplasm
  rationale: >-
    This entry's mechanism predicts that removing the tumour should remove the disease,
    because the tumour is the antibody source. Mucocutaneous disease does behave roughly
    that way. The airways do not: bronchiolitis obliterans is described as leaving lung
    transplantation as often the only viable option specifically once the neoplasm has been
    controlled.

    The possibilities are not distinguished by anything curated here. The scarring may
    simply be structurally irreversible once established, in which case the failure is one
    of timing rather than of mechanism and the implication is that airway disease must be
    detected earlier. Or the airway lesion may be sustained by a process that outlives the
    antibody - the cell-mediated arm, or a self-perpetuating fibrotic response of the kind
    seen in obliterative bronchiolitis after transplantation, which would make it a
    different disease from the mucocutaneous one sharing a trigger.

    Nothing in the cited work establishes even that the airway lesion is antibody-mediated
    at all, which is why the edge to this node is curated with unknown intermediates.
  proposed_experiments:
  - experiment_id: serial_airway_assessment_after_tumour_control
    name: Serial physiological and histological airway assessment through tumour control
    description: >-
      Follow lung function and, where tissue is available, airway histology in patients from
      before tumour control through remission, to establish whether early airway disease is
      reversible and at what point it ceases to be. If early disease remits, the failure is
      one of detection; if it never remits at any stage, the airway arm is driven by
      something the antibody does not control.

notes: >-
  Naming. The disease has two names and the entry uses both: paraneoplastic pemphigus is
  the MONDO label and the term clinicians reach for, paraneoplastic autoimmune multiorgan
  syndrome is the more accurate description of a disease whose fatal complication is in the
  lungs. MONDO places the term under both autoimmune bullous skin disease and paraneoplastic
  cutaneous syndrome, and that dual parentage is right.

  Contrast with the other paraneoplastic autoimmune syndromes. In Lambert-Eaton myasthenic
  syndrome, also curated in this knowledge base, small-cell lung carcinoma expresses a
  neuronal antigen ectopically and the anti-tumour immune response cross-reacts with the
  same antigen at the nerve terminal - the tumour provokes the response. Here, tumour cells
  of Castleman disease were shown to secrete anti-plakin antibodies themselves. Those are
  different mechanisms with the same clinical shape, and the difference has a therapeutic
  consequence: removing the tumour removes the antibody source directly rather than removing
  the stimulus for an established autoimmune response.

  What is deliberately not claimed. The link from the mucocutaneous mechanism to the airway
  disease is curated INDIRECT_UNKNOWN_INTERMEDIATES because no cited source shows the airway
  lesion is produced by the same autoantibodies. Respiratory epithelium does express
  plakins, and that is the obvious hypothesis, but obvious is not the same as demonstrated
  and the entry does not assert it.

  Frequency bands. Two are assigned, both from direct qualitative statements in the cited
  review - "typically present" for the mucocutaneous features and "a frequent complication"
  for bronchiolitis obliterans. Acantholysis carries no band because it is a histological
  finding reported in individual cases rather than a frequency in a series.

  No GeneReviews baseline applies. This is an acquired paraneoplastic autoimmune disease
  with no Mendelian form; a GeneReviews search returns nothing relevant.

  Prognostic data are syntheses of case reports, not cohorts. Three sources are curated -
  a 504-patient systematic review, a 144-patient review restricted to haematologic
  malignancy, and the EADV guideline's citation of a 53-patient French multicentre series -
  and their mortality estimates do not agree (90% at two years, 57%, one-year survival
  49%). These are the largest syntheses available for a disease this rare and they are
  still built from case reports with the selection biases that implies. The hazard ratios
  and rates are curated because they are the best available, not because they are robust.

  Castleman disease is curated as a tumour type, not cross-linked as a comorbidity. The
  Disease class has no comorbidities slot, and the relationship here is not comorbidity in
  any case - the tumour is this entry's trigger node. Castleman_Disease and
  Multicentric_Castleman_Disease both exist in this knowledge base and neither is
  referenced from here, because there is no slot in which such a reference would mean
  anything more than the prose already does. The quantitative link is instead curated as
  evidence on the trigger node: Castleman disease in up to 56% of patients, more frequent
  in Asian countries, and a favourable prognostic factor.

  Orphanet has no epidemiology for this disorder. ORPHA:63455 was built from the pinned
  Orphadata snapshot and carries a definition and five cross-references, but no prevalence
  table and no HPO frequency table - so the incidence figure comes from the EADV S2k
  guideline, and the frequency bands remain hand-assigned from qualitative statements as
  described above. Recorded because the absence is easy to assume away.

  Two things the review suggested and this entry does not do, recorded so the decisions are
  explicit rather than silent. The five polymorphous cutaneous patterns (pemphigus-like,
  pemphigoid-like, erythema-multiforme-like, GVHD-like, lichen-planus-like) are curated as
  a single Cutaneous Blistering phenotype. The polymorphism is diagnostically load-bearing -
  it is part of why this disease is misdiagnosed - and two of the patterns
  (toxic-epidermal-necrolysis-like and bullous-pemphigoid-like) are independent adverse
  survival factors, so they arguably deserve separate phenotypes. Deferred rather than
  dismissed: doing it properly means deciding whether they are phenotypes, subtypes, or
  severity strata, and that decision should not be made in a review-response commit. The
  other is peri-operative IVIG, discussed on the treatment entry.

  Deep research. A claude_code provider run
  (research/Paraneoplastic_Pemphigus-deep-research-claude_code.md) was performed after the
  first draft. Its own reference validation reports 16 of 16 identifiers resolved, none
  unresolved, 11 of 16 scored on topic and none off topic - so five are undecided rather
  than cleared. It surfaced two references this entry now uses: the JAAD CME Part II and
  the 144-patient risk-factor review. It did not surface the EADV S2k guideline, which is
  the single most productive source in the entry and was found instead by following a
  corrigendum in a PubMed title search.

  A veterinary review of deep pemphigus in dogs, cats and horses (PMID:33228633) was
  surfaced and fetched but is not curated. Naturally occurring paraneoplastic pemphigus in
  companion animals would be a genuine animal_models entry rather than an induced model,
  which is exactly why it should not be added on the strength of a title - it needs the
  same reading of the primary text that everything else here got, and that is left for a
  follow-up.

references:
- reference: PMID:37597771
  title: "Paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome: Part I. Clinical overview and pathophysiology."
- reference: PMID:35911677
  title: "Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo."
- reference: PMID:39426525
  title: "A systematic review of paraneoplastic pemphigus and paraneoplastic autoimmune multiorgan syndrome: Clinical features and prognostic factors."
- reference: PMID:41483625
  title: "From the archives of MD Anderson Cancer Center: Paraneoplastic autoimmune multiorgan syndrome (PAMS) associated with stroma-rich Castleman disease."
- reference: PMID:36965110
  title: "S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV)."
- reference: PMID:37714216
  title: "Paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome: Part II. Diagnosis and management."
- reference: PMID:30981429
  title: "Risk factors for death and survival in paraneoplastic pemphigus associated with hematologic malignancies in adults."
- reference: ORPHA:63455
  title: "Paraneoplastic pemphigus"
📚

References & Deep Research

References

8
PMID:37597771
Paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome: Part I. Clinical overview and pathophysiology.
No top-level findings curated for this source.
PMID:35911677
Paraneoplastic Pemphigus Autoantibodies Against C-terminus of Desmoplakin Induced Acantholysis In Vitro and In Vivo.
No top-level findings curated for this source.
PMID:39426525
A systematic review of paraneoplastic pemphigus and paraneoplastic autoimmune multiorgan syndrome: Clinical features and prognostic factors.
No top-level findings curated for this source.
PMID:41483625
From the archives of MD Anderson Cancer Center: Paraneoplastic autoimmune multiorgan syndrome (PAMS) associated with stroma-rich Castleman disease.
No top-level findings curated for this source.
PMID:36965110
S2k guidelines on the management of paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome initiated by the European Academy of Dermatology and Venereology (EADV).
No top-level findings curated for this source.
PMID:37714216
Paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome: Part II. Diagnosis and management.
No top-level findings curated for this source.
PMID:30981429
Risk factors for death and survival in paraneoplastic pemphigus associated with hematologic malignancies in adults.
No top-level findings curated for this source.
ORPHA:63455
Paraneoplastic pemphigus
No top-level findings curated for this source.

Deep Research

1
Claude Code ▸
Paraneoplastic Pemphigus (PNP) / Paraneoplastic Autoimmune Multiorgan Syndrome (PAMS): Comprehensive Research Report
claude-haiku-4-5-20251001, claude-sonnet-5 23 citations 2026-08-22T04:48:48.971935

Paraneoplastic Pemphigus (PNP) / Paraneoplastic Autoimmune Multiorgan Syndrome (PAMS): Comprehensive Research Report

1. Disease Information

Overview: Paraneoplastic pemphigus (PNP), also increasingly termed paraneoplastic autoimmune multiorgan syndrome (PAMS), is a rare, highly fatal autoimmune mucocutaneous blistering disease that arises in patients with an underlying benign or malignant neoplasm — most commonly a lymphoproliferative disorder. First described by Anhalt et al. in 1990, it is immunologically and clinically distinct from other pemphigus variants, defined by circulating autoantibodies against desmosomal cadherins (desmogleins 1 and 3) and the plakin family of cytoskeletal-linker proteins, combined with a strong cell-mediated (cytotoxic T-cell) component. The term PAMS, proposed in 2001, was introduced to capture the disease's polymorphous mucocutaneous presentation, immunologic abnormalities, and potential for multi-organ (notably pulmonary) involvement, distinguishing it from "classic" pemphigus that happens to co-occur with a tumor (StatPearls; JAAD Part I, PMID:37597771).

Key identifiers: | Resource | ID | |---|---| | MONDO | MONDO:0018974 | | Orphanet | ORPHA:63455 | | ICD-11 | EB40.2 | | ICD-10-CM | L10.81 | | OMIM | Not listed (not a monogenic/Mendelian disorder) | | MeSH | Pemphigus, subheading "Paraneoplastic" (D016883 parent) |

Sources: Orphanet, ICD10Data, Wikidata Q1394580

Synonyms: Paraneoplastic autoimmune multiorgan syndrome (PAMS); PNP; paraneoplastic autoimmune bullous disease.

Evidence base: Because PNP is exceedingly rare, virtually all data derive from aggregated case reports, case series, and retrospective cohort studies (largest series ~144–149 patients) rather than large prospective EHR-derived cohorts; there are no population-based registries.

2. Etiology

Disease Causal Factors

PNP is not caused by a germline mutation; it is a tumor-triggered autoimmune syndrome. An underlying neoplasm — most often lymphoproliferative — is believed to trigger aberrant B-cell and T-cell responses that cross-react with epithelial adhesion-complex proteins (molecular mimicry / epitope spreading hypothesis), producing pathogenic autoantibodies and autoreactive cytotoxic T cells (StatPearls; JAAD Part I).

Associated Neoplasms (Risk Factor: presence of these tumors)

Across pooled case series, the underlying neoplasm distribution is approximately: - Non-Hodgkin lymphoma — 38.6% (largest series with hematologic malignancy: 52.78%) - Chronic lymphocytic leukemia (CLL) — 18.4% (up to 22.92% in some series) - Castleman disease — 18.4% (up to 18.60%); this is the dominant association in children and adolescents, given Castleman disease's rarity in the general population but disproportionate co-occurrence with pediatric PNP - Thymoma — 5.5% - Waldenström macroglobulinemia — 1.2% - Hodgkin lymphoma — 0.6% - Monoclonal gammopathy — 0.6% - Solid tumors: follicular dendritic cell sarcoma, squamous cell carcinoma, and carcinomas of lung, stomach, colon

Lymphoproliferative neoplasms overall account for ~84% of PNP cases (StatPearls). In ~30% of cases, PNP is the first clinical manifestation of an occult neoplasm, meaning the skin/mucosal disease precedes cancer diagnosis. Sources: PMC11587122, Risk factors for death and survival, PMID:30981429.

Genetic Risk Factors

  • HLA-DRB1*03 — associated with increased PNP susceptibility in French Caucasian populations
  • HLA-Cw*14 — associated in Chinese populations
  • In Chinese Han patients, HLA-B*4002/B*4004, B*51, B*52, Cw*14, DQB1*0301, DRB1*08, and DRB1*11 were relatively enriched versus controls
  • Notably, HLA-DR4 and DR1/DR14, which confer risk for pemphigus vulgaris and pemphigus foliaceus, show no association with PNP — underscoring PNP's distinct immunogenetic basis from classic pemphigus

Source: PMC7341728, "Beyond the HLA polymorphism"; StatPearls.

Environmental / Age / Sex Risk Factors

  • Age: typical onset 45–70 years (mean ~64.7 years); pediatric cases occur, strongly linked to Castleman disease
  • Sex: roughly equal male:female distribution (no strong sex predilection reported)
  • No established toxin, occupational, or infectious trigger independent of the neoplasm itself

Protective Factors

No specific genetic or environmental protective factors have been established in the literature; this is consistent with PNP's status as a rare, tumor-driven paraneoplastic syndrome rather than a polygenic/environmentally-modulated common disease.

Gene-Environment Interactions

Not well characterized beyond the HLA-neoplasm relationship above; the operative model is that neoplasm-driven immune dysregulation (particularly IL-6-producing lymphoproliferative tissue, as in Castleman disease) interacts with HLA-restricted antigen presentation to drive autoreactive B- and T-cell clones.

3. Phenotypes

Mucosal (earliest and most consistent feature)

PNP "almost always presents with early mucosal involvement," typically severe, painful, treatment-refractory oral mucosal erosions/ulcerations that may be the sole presenting sign. Involvement can extend to the vermilion border, tongue, oropharynx, nasopharynx, esophagus, conjunctiva, and anogenital mucosa (StatPearls). - Suggested HPO terms: HP:0032247 (Oral mucosal blister-like lesion) / HP:0002745 (Ulcerated skin lesion) — oral erosions specifically map best to general mucosal ulceration/erosion terms; conjunctival scarring maps to HP:0007957 (corneal/conjunctival scarring-type terms) or HP:0000581 (Blepharophimosis-adjacent conjunctival terms; more precisely conjunctival scarring/symblepharon).

Cutaneous — Five Clinical Subtypes (polymorphous)

  1. Pemphigus-like: flaccid vesicles/bullae, crusted erosions (intraepidermal/suprabasal acantholysis)
  2. Pemphigoid-like: tense subepidermal blisters, scaling erythematous plaques
  3. Erythema multiforme-like (most common presentation, ~56%): polymorphic targetoid/erythematous lesions with dyskeratosis
  4. Graft-versus-host disease-like: diffuse dusky, scaly papules
  5. Lichen planus-like: violaceous flat-topped papules with lichenoid infiltrate

Source: StatPearls; DermNet.

Extracutaneous/Multi-organ Involvement (the "multiorgan" in PAMS)

  • Ocular: up to 70% of patients; pseudomembranous conjunctivitis, progressive cicatrizing conjunctival scarring, corneal erosion, pterygium — potential for irreversible blindness
  • Pulmonary: 59.1–92.8% of cases; dyspnea, dry cough, obstructive lung disease progressing to bronchiolitis obliterans (incidence estimates 27–93% across studies) — a leading cause of death
  • Myasthenic symptoms: 39% of studied patients report symptoms; 35% meet criteria for myasthenia gravis by anti-acetylcholine-receptor antibody titer, especially with thymoma-associated PNP
  • Gastrointestinal: esophageal erosions, dysphagia
  • Additional reported organ involvement: thyroid, kidney

Source: StatPearls; PMC11277726 (airway involvement).

Laboratory/Immunologic Abnormalities

Circulating autoantibodies against plakin-family proteins and desmogleins (see Section 4); elevated inflammatory markers related to the underlying lymphoproliferative disease.

Phenotype Characteristics

  • Onset: adult (45–70y peak) but can occur in children/adolescents (Castleman-associated)
  • Severity: variable but generally severe; extensive mucocutaneous involvement is an adverse prognostic sign
  • Progression: often relapsing/progressive; cutaneous lesions may improve within ~12 weeks of treatment, but mucosal disease is frequently refractory
  • Frequency of specific manifestations: erythema multiforme-like cutaneous pattern in 56%; ocular in up to 70%; pulmonary in 59–93%; myasthenic symptoms in 39%

Quality of Life Impact

Severe painful oral erosions impair eating/nutrition (frequently requiring nasogastric feeding); ocular scarring can cause permanent visual impairment; bronchiolitis obliterans causes progressive, often fatal, respiratory disability; extensive skin denudation requires burn-unit–level wound care and carries infection/sepsis risk.

Suggested HPO terms for pathophysiology-related phenotypes: HP:0200042 (Skin ulcer), HP:0100836 (Blistering) type terms, HP:0002206 (Pulmonary fibrosis/obliterans-adjacent — bronchiolitis obliterans itself has no precise dedicated HPO term but maps near obstructive lung disease terms), HP:0000546 (Blindness), HP:0003324 (Generalized muscle weakness — myasthenic).

4. Genetic/Molecular Information

PNP is not a Mendelian genetic disease — there is no single causal gene. Instead, disease-defining molecular features are the autoantibody targets:

Target Antigens (Plakin Family + Desmosomal Cadherins)

Antigen MW Notes
Desmoplakin I 250 kDa Most consistently detected by immunoprecipitation
BP230 (bullous pemphigoid antigen 1) 230 kDa Also targeted in bullous pemphigoid
Desmoplakin II 210 kDa
Envoplakin 210 kDa Along with periplakin, the most characteristic/consistently recognized PNP antigen
Periplakin 190 kDa
Plectin ~500 kDa
Epiplakin — Specifically associated with bronchiolitis obliterans development
α2-macroglobulin-like-1 (A2ML1) 170 kDa A protease inhibitor, not a classic plakin
Desmoglein 3 (Dsg3) — Shared with pemphigus vulgaris
Desmoglein 1 (Dsg1) — Shared with pemphigus foliaceus

Sources: PMC6558011; PMC9332891 — anti-desmoplakin C-terminus antibodies induce acantholysis in vivo; Frontiers 10.3389/fimmu.2022.886226.

Functional Consequence

Plakin proteins are cytolinkers connecting the keratin intermediate filament cytoskeleton to desmosomes and hemidesmosomes. Autoantibody binding — particularly against the desmoplakin C-terminus — directly disrupts desmosomal adhesion, producing acantholysis (loss of keratinocyte cell-cell adhesion), demonstrated experimentally in murine models (dose-dependent blister/acantholysis induction and keratinocyte apoptosis after antibody injection in neonatal mice).

Modifier/Susceptibility Genes

HLA-DRB1*03 (Caucasian), HLA-Cw*14 (Chinese) — see Section 2.

Epigenetics / Chromosomal Abnormalities

Not specifically characterized for PNP; the underlying lymphoproliferative neoplasm (e.g., CLL, follicular lymphoma) may carry its own somatic cytogenetic lesions (e.g., t(14;18) in follicular lymphoma), but these are neoplasm-intrinsic rather than PNP-defining.

Suggested gene/protein annotation terms (HGNC): DSP (desmoplakin), EVPL (envoplakin), PPL (periplakin), DST/BPAG1 (BP230/dystonin), PLEC (plectin), PKP1-3 (plakophilins, less characteristic), DSG1, DSG3, A2ML1.

5. Environmental Information

There is no established environmental toxin, radiation, or occupational exposure directly implicated in PNP etiology. The dominant "environmental" trigger, functionally, is the presence of the associated neoplasm itself (see Section 2), which is presumed to drive antigen release/molecular mimicry and cytokine-driven (e.g., IL-6, particularly relevant in Castleman disease) immune dysregulation. No specific infectious agent has been established as causal for PNP itself (distinct from its associated neoplasms, some of which — e.g., certain lymphomas — may have viral associations such as EBV, though this is not PNP-specific).

6. Mechanism / Pathophysiology

Causal Chain (Trigger → Manifestation)

  1. Underlying neoplasm (lymphoproliferative disorder, thymoma, or Castleman disease) → dysregulated B- and T-cell immunity
  2. Autoantibody production against plakin-family desmosomal/hemidesmosomal linker proteins (envoplakin, periplakin, desmoplakins, BP230, plectin, epiplakin) and desmogleins (Dsg1/Dsg3) — proposed mechanism includes molecular mimicry between tumor antigens and epithelial adhesion proteins
  3. Autoantibody binding disrupts desmosome-cytoskeleton linkage → acantholysis (intraepidermal keratinocyte separation) — directly demonstrated for anti-desmoplakin C-terminus antibodies in vivo (murine skin) and in vitro
  4. Concurrent cell-mediated cytotoxicity: autoreactive CD4+ and CD8+ T cells (including a Th17-skewed, T follicular helper-like Dsg3-reactive population) infiltrate lesional tissue, producing interface dermatitis with keratinocyte apoptosis/necrosis — a histologic and mechanistic feature that distinguishes PNP from antibody-only-mediated pemphigus vulgaris
  5. Multi-organ epithelial targeting: because plakins/desmosomes are expressed broadly across stratified and transitional epithelia (skin, oral/esophageal mucosa, conjunctiva) and — critically — in bronchial epithelium, the same autoimmune attack extends to the respiratory tract, producing bronchiolitis obliterans (epiplakin autoantibodies specifically implicated), the dominant driver of PNP mortality.

Molecular/Cellular Processes

  • Loss of keratinocyte-keratinocyte adhesion (desmosome disruption)
  • Keratinocyte apoptosis/necrosis (dyskeratosis)
  • Basal layer vacuolization (interface dermatitis pattern)
  • Lymphocytic exocytosis into epithelium
  • Bronchiolar epithelial injury, fibrosis, and obliteration (bronchiolitis obliterans) — lung biopsy shows bronchiole fibrosis, dense lymphohistiocytic infiltrates, and autoantibody deposition

Suggested GO terms: GO:0007156 (homophilic cell adhesion via plasma membrane adhesion molecules), GO:0030057 (desmosome), GO:0006915 (apoptotic process), GO:0002250 (adaptive immune response), GO:0042113 (B cell activation).

Suggested CL terms: CL:0000312 (keratinocyte), CL:0000000 downstream — specifically stratified squamous epithelial cell; CL:0000784 (plasmacytoid... not applicable) — better: CL:0000542 (lymphocyte), CL:0000625 (CD8-positive alpha-beta T cell), CL:0000546 (T-helper cell).

Suggested UBERON terms: UBERON:0001003 (skin epidermis), UBERON:0001744 (tonsil/oral mucosa-adjacent), UBERON:0006562 (oral mucosa), UBERON:0002185 (bronchiole), UBERON:0001772 (conjunctiva).

Molecular Profiling / Advanced Technologies

The literature on PNP is dominated by immunoprecipitation/immunoblot and ELISA-based antigen characterization rather than modern multi-omic (transcriptomic/proteomic/single-cell) profiling; no major GEO/single-cell atlas datasets specific to PNP were identified in this search. This represents a notable data gap relative to other autoimmune skin diseases.

Source: PMC6558011; PMC9332891; JCI 29403 — Dsg3-specific CD4+ T cells induce pemphigus and interface dermatitis in mice; PMC10107879 — T cell autoimmunity to Dsg3.

7. Anatomical Structures Affected

  • Organ level: skin (epidermis), oral cavity, oropharynx, nasopharynx, esophagus, conjunctiva/cornea, anogenital mucosa, lungs/bronchioles, and (via associated myasthenia gravis) neuromuscular junction; kidney and thyroid involvement reported less commonly
  • Body systems: integumentary, mucosal/gastrointestinal, ocular, respiratory, and (secondarily) neuromuscular
  • Tissue/cell level: stratified squamous epithelium (skin, oral mucosa, esophagus, conjunctiva), transitional epithelium (bladder — relevant diagnostically, see Section 10), bronchiolar epithelium; keratinocytes are the principal targeted cell population
  • Subcellular: desmosomes and hemidesmosomes (cell junction complexes); keratin intermediate filament cytoskeleton
  • Localization: bilateral/diffuse, non-lateralized involvement typical

Suggested UBERON: UBERON:0001003 (epidermis), UBERON:0006562 (oral mucosa), UBERON:0001043 (esophagus), UBERON:0001772 (conjunctiva), UBERON:0002185 (bronchiole), UBERON:0001255 (urinary bladder — diagnostic substrate).

8. Temporal Development

  • Onset: adult, typically 45–70 years; pediatric onset associated with Castleman disease; onset is typically subacute, beginning with refractory oral mucositis
  • Progression: cutaneous lesions may resolve within ~12 weeks of treatment; mucosal lesions are frequently persistent/poorly responsive; pulmonary disease (bronchiolitis obliterans) is often progressive and irreversible
  • Disease course pattern: variable — can be relapsing or steadily progressive; "there is not always a parallel evolution between PNP severity and the malignancy's treatment response," meaning cutaneous/mucosal/pulmonary disease can progress even after successful cancer treatment (StatPearls)
  • Duration: chronic when survived; however most patients die within one year of diagnosis
  • Remission: possible with successful resection/treatment of a benign underlying tumor (e.g., Castleman disease, localized thymoma), which offers the best prognosis

9. Inheritance and Population

Epidemiology

  • PNP accounts for only 3–5% of all pemphigus cases (pemphigus overall is itself rare)
  • No formal population-based incidence/prevalence rate has been established (extremely rare disease, case-series-based literature only)

Inheritance

  • Not a Mendelian inherited disease — no defined inheritance pattern (AD/AR/X-linked); susceptibility is polygenic/immunogenetic (HLA-associated) combined with an acquired triggering neoplasm
  • No known penetrance, expressivity, anticipation, mosaicism, or carrier-frequency concepts apply, as this is an acquired paraneoplastic autoimmune disease, not a germline genetic disorder

Population Demographics

  • Sex ratio: approximately equal (M:F ~1:1)
  • Age distribution: mean age at diagnosis ~64.7 years in adult series; a distinct pediatric/adolescent cluster exists, driven by Castleman disease association
  • Ethnic/geographic variation is reflected mainly in differing HLA-risk-allele profiles (Caucasian: DRB1*03; Chinese: Cw*14 and related alleles) rather than differential prevalence data

Sources: StatPearls; PMC7341728.

10. Diagnostics

Diagnostic Criteria Frameworks

Three overlapping criteria systems are used:

1. Anhalt's original criteria (5 components): - Clinical: painful mucosal erosions ± polymorphous cutaneous lesions with an underlying malignancy - Histopathology: suprabasal acantholysis, interface dermatitis, keratinocyte necrosis - Direct immunofluorescence (DIF): IgG/C3 in intercellular spaces ± basement membrane zone - Indirect immunofluorescence (IIF) on rat/murine bladder transitional epithelium - Immunoprecipitation: characteristic plakin protein pattern (250, 230, 210, 190, 170 kDa bands)

2. Joly criteria (high specificity 84–100%, sensitivity 82–86%): (a) underlying lymphoproliferative disorder, (b) IIF-positive on rat bladder, (c) anti-periplakin/anti-envoplakin autoantibodies by immunoblot.

3. Camisa and Helm major/minor criteria: requires 3 major, or 2 major + 2 minor criteria (major: polymorphic mucocutaneous eruption, concomitant neoplasm, characteristic immunoprecipitation pattern; minor: histologic acantholysis, DIF pattern, positive rat bladder IIF).

Key Test Characteristics

  • DIF can be negative in up to 50% of cases — a negative DIF does NOT exclude PNP
  • IIF on rodent/murine bladder: sensitivity ~75%, specificity ~83%; negative/indeterminate in up to one-fourth of patients — an adequate screening test but not conclusive alone; useful for discriminating PNP from pemphigus vulgaris/foliaceus (which are typically negative on this substrate)
  • Immunoblot is considered the gold standard, detecting anti-envoplakin (210 kDa)/anti-periplakin (190 kDa) reactivity with high sensitivity/specificity
  • ELISA assays for anti-envoplakin/anti-periplakin antibodies are also available and increasingly used

Additional Malignancy Workup

Once PNP is suspected: CBC, LDH, flow cytometry, and cross-sectional imaging (chest/abdomen/pelvis) to identify an occult neoplasm.

Differential Diagnosis

Stevens-Johnson syndrome/toxic epidermal necrolysis (erythema multiforme-like PNP is often mistaken for these), erythema multiforme, lichen planus, graft-versus-host disease, HSV infection, drug-induced pemphigus, pemphigus vulgaris, mucous membrane pemphigoid, bullous pemphigoid, staphylococcal scalded skin syndrome, chemotherapy-induced stomatitis.

Sources: StatPearls; ScienceDirect (S0365059620306310); Accuracy of IIF, ScienceDirect 0190962295900667.

11. Outcome/Prognosis

  • Mortality: 70–90% (StatPearls cites "approaching 90%"); one large hematologic-malignancy-associated cohort (n=144) reported an overall mortality rate of 57%. Most patients die within one year of diagnosis.
  • Causes of death: widespread cutaneous infection/sepsis (loss of skin barrier), progression of the underlying malignancy, and bronchiolitis obliterans-related respiratory failure — the latter is frequently cited as the single most common proximate cause of death
  • Adverse prognostic factors: keratinocyte necrosis on histology, erythema multiforme-like or TEN-like or bullous-pemphigoid-like cutaneous presentation, extensive mucocutaneous disease at presentation, presence of envoplakin autoantibodies, and development of bronchiolitis obliterans
  • Favorable factors: resectable/benign underlying tumor (localized Castleman disease, encapsulated thymoma) is associated with markedly better outcomes than diffuse lymphoproliferative malignancy
  • Bronchiolitis obliterans specifically: affects 27–93% of patients across studies (StatPearls cites 30–90%); may require lung transplantation in severe cases
  • Complication burden: irreversible blindness (ocular scarring), fluid/electrolyte derangement from cutaneous erosions, malnutrition from oral involvement (often requiring NG feeding), contractures requiring rehabilitation

Sources: Risk factors for death, PMID:30981429; PMC9060127 — BO requiring lung transplant; StatPearls.

12. Treatment

First-Line

High-dose systemic corticosteroids remain first-line therapy for PNP disease control (StatPearls; 2025 systematic review). NCIT term: NCIT:C15986 (Pharmacotherapy) with therapeutic_agent bound to corticosteroid class (e.g., NCIT:C2280 Prednisone / NCIT:C2322 Corticosteroid class).

Steroid-Sparing / Immunosuppressive Agents

  • Azathioprine, mycophenolate mofetil, cyclosporine, cyclophosphamide — added for steroid-refractory disease
  • NCIT: NCIT:C15632 (Chemotherapy) or NCIT:C15986 (Pharmacotherapy) + therapeutic_agent

Biologics

  • Rituximab (anti-CD20 monoclonal antibody) — shown efficacious particularly in lymphoproliferative-malignancy-associated PNP; NCIT: NCIT:C1932 (Rituximab); therapeutic_modality: MONOCLONAL_ANTIBODY
  • Alemtuzumab (anti-CD52) — used in select cases
  • A 2025 systematic review (Advances in Rheumatology) of rituximab + IVIG combination therapy across autoimmune bullous disease found positive outcomes in all but one reported PNP case, though infection risk (e.g., P. jirovecii pneumonia) was noted as a safety concern

Intravenous Immunoglobulin (IVIG)

Used both as adjunct therapy and, notably, peri-operatively (before/after surgical resection of the underlying tumor) — proposed to reduce bronchiolitis-obliterans risk by neutralizing released autoantibodies at the time of tumor lysis. NCIT: NCIT:C15986/therapeutic_agent immunoglobulin.

Plasmapheresis

Used adjunctively in refractory/severe disease.

Malignancy-Directed Therapy

Early diagnosis and definitive treatment of the underlying neoplasm is paramount — surgical resection for solid/localized tumors (thymoma, Castleman disease), and lymphoma/CLL-directed chemoimmunotherapy (e.g., R-CHOP regimens) for lymphoproliferative disease. Notably, mucocutaneous disease does not always parallel malignancy treatment response.

Supportive/Wound Care (burn-unit level)

Occlusive hydrating dressings, warm-water compresses, low-adhesive/petrolatum dressings, silver antimicrobial dressings, topical corticosteroids/calcineurin inhibitors, triamcinolone gel and analgesic mouthwash for oral lesions, nasogastric feeding, pressure-ulcer prevention, antiseptic care, and systemic antibiotics for secondary infection.

Multidisciplinary Team

Oncology, dermatology, ophthalmology, pulmonology, gastroenterology, urology, infectious disease, wound care nursing, nutrition, and mental health support.

Experimental / Emerging

Lung transplantation has been reported for end-stage bronchiolitis obliterans in PNP associated with Castleman disease. Newer B-cell-depleting agents used in refractory classic pemphigus (e.g., inebilizumab) are an area of emerging interest but lack dedicated PNP data.

Sources: StatPearls; Advances in Rheumatology systematic review, 2025; PMC9060127; International Journal of Hematology — R-CHOP long-term survival case.

13. Prevention

There is no established primary prevention strategy for PNP, as it arises unpredictably in association with an underlying neoplasm. The literature emphasizes: - Secondary prevention / early detection: prompt malignancy workup (CBC, LDH, flow cytometry, imaging) in any patient presenting with refractory mucocutaneous erosions and a polymorphous eruption, since PNP precedes malignancy diagnosis in ~30% of cases - Tertiary prevention: perioperative IVIG administration around tumor resection, proposed to blunt autoantibody-mediated bronchiolar injury and reduce bronchiolitis obliterans risk - Genetic counseling is not applicable given the non-Mendelian, acquired nature of the disease - Ophthalmology and pulmonology surveillance are recommended early in the disease course to catch ocular scarring and early bronchiolitis obliterans before irreversible damage occurs

14. Other Species / Natural Disease

PNP is one of the few paraneoplastic autoimmune blistering diseases with documented spontaneous veterinary analogs: - Dogs: paraneoplastic pemphigus has been reported in association with splenic sarcoma and other neoplasms; canine disease shares clinical and immunopathologic features with human PNP (Elmore et al. 2005, Vet Pathol) - Cats and horses: also reported, reviewed comprehensively alongside canine/feline/equine pemphigus vulgaris and pemphigus vegetans in a 2020 BMC Veterinary Research review (PMID:33228633; PMC7686683) - Prognosis in veterinary PNP is described as "grave," paralleling the poor human prognosis; treatment follows similar high-dose glucocorticoid ± immunosuppressant principles as pemphigus vulgaris/vegetans in animals, though PNP itself is noted as rare in dogs specifically associated with neoplasia

NCBI Taxon: dog (NCBITaxon:9615), cat (NCBITaxon:9685), horse (NCBITaxon:9796). No OMIA (Online Mendelian Inheritance in Animals) entry was surfaced, consistent with PNP's non-Mendelian, acquired etiology in animals as in humans.

15. Model Organisms

  • In vivo murine models: Neonatal/adult mouse skin injection models have been used to demonstrate pathogenicity of PNP autoantibodies — specifically, anti-desmoplakin C-terminus IgG induced dose-dependent blister formation and acantholysis in mouse skin, with keratinocyte apoptosis observed in neonatal mice after antibody passive transfer (PMC9332891; Frontiers 10.3389/fimmu.2022.886226). These are passive-transfer/induced models, not genetic knockouts, and directly recapitulate acantholysis and blister formation but not the full multi-organ (pulmonary/ocular) phenotype or the underlying neoplasm trigger.
  • Related pemphigus vulgaris T-cell models: Dsg3-specific CD4+ T-cell transfer models in mice induce pemphigus-like blistering and interface dermatitis, a histologic hallmark shared with PNP, providing a mechanistic model for the T-cell-mediated component of PNP pathogenesis even though these studies were performed in a pemphigus vulgaris (not PNP) context (JCI 29403; PMC10107879).
  • Limitations: No model fully recapitulates the tumor-triggered, multi-antigen (plakin + desmoglein), multi-organ (skin + mucosa + lung) nature of human PNP; existing models isolate single antibody specificities or T-cell clones rather than the full autoimmune repertoire seen clinically. No PNP-specific knockout, transgenic, humanized, or organoid/iPSC model system was identified in this search — representing a clear research gap relative to pemphigus vulgaris, for which more developed genetic mouse models exist.

Summary of Suggested Ontology Term Bindings for KB Curation

Category Suggested terms
Disease MONDO:0018974
Causal genes (autoantigens) hgnc: DSP, EVPL, PPL, DST (BP230), PLEC, DSG1, DSG3, A2ML1
Phenotypes (HP) oral/mucosal erosion, conjunctival scarring, blindness, obstructive lung disease/bronchiolitis obliterans (nearest available term), generalized muscle weakness (myasthenic)
Cell types (CL) CL:0000312 (keratinocyte), CL:0000625 (CD8+ T cell), CL:0000546 (T-helper cell), CL:0000236 (B cell)
Biological processes (GO) GO:0007156 (cell-cell adhesion), GO:0030057 (desmosome), GO:0006915 (apoptosis)
Anatomy (UBERON) UBERON:0001003 (epidermis), UBERON:0006562 (oral mucosa), UBERON:0002185 (bronchiole), UBERON:0001772 (conjunctiva)
Treatments (NCIT) NCIT:C15986 (Pharmacotherapy) + therapeutic_agent (corticosteroid, rituximab NCIT:C1932, IVIG), NCIT:C15329 (Surgical Procedure) for tumor resection

Key Citations

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