Sarcoidosis

Immune MONDO:0019338 Pathograph 14 Granulomatous Disease Immune-Mediated Disease

Sarcoidosis is a multisystem inflammatory disease of unknown etiology characterized by the formation of non-caseating granulomas, most commonly affecting the lungs and lymph nodes. The leading model holds that genetically susceptible individuals (HLA-DRB1, BTNL2, ANXA11, NOTCH4, IL27RA risk alleles) mount an exaggerated CD4+ T-cell response to a poorly degradable antigen (mycobacterial KatG/ESAT-6, propionibacterial, or environmental dusts), driving Th1/Th17.1-skewed inflammation, IFN-gamma production, and macrophage transformation into epithelioid and multinucleated giant cells organized into granulomas. Macrophage-intrinsic mTORC1 hyperactivation sustains granuloma maintenance and correlates with progressive disease. The disease predominantly affects adults aged 20-40 years, with higher incidence in African Americans and Northern Europeans. Clinical presentation ranges from asymptomatic to severe organ dysfunction; while many cases resolve spontaneously, chronic progressive disease (10-30%) progresses to pulmonary fibrosis, cardiac, neurologic, ocular, or cutaneous involvement.

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Inheritance

Polygenic susceptibility

Sarcoidosis is not a Mendelian disorder but shows familial clustering with polygenic susceptibility (HLA-DRB1, BTNL2, ANXA11). Risk is increased in first-degree relatives.

Show evidence (1 reference)

PMID:27454307 SUPPORT Human Clinical

"Familial clusters can occur."

Familial clustering supports genetic predisposition without Mendelian inheritance.

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Subtypes

Pulmonary Sarcoidosis

Most common form, affecting lungs and hilar lymph nodes; staged by chest radiograph findings.

Cardiac Sarcoidosis

Myocardial granulomas causing conduction abnormalities, heart failure, or sudden death.

Neurosarcoidosis

CNS involvement causing cranial neuropathies, meningitis, or mass lesions.

Cutaneous Sarcoidosis

Skin manifestations including erythema nodosum, lupus pernio, and papular lesions.

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Mechanistic Hypotheses

Antigen Persistence / Th17.1 / mTORC1 Granuloma Chronicity Model

antigen_persistence_granuloma_chronicity_model EMERGING Pulmonary Sarcoidosis

Sarcoidosis is modeled as a genetically conditioned, antigen-driven granulomatous immune response in which poorly degradable or repeatedly encountered antigens are presented by macrophage-lineage antigen-presenting cells to CD4+ T cells. The activated T-cell compartment polarizes toward IFN-gamma-producing Th17.1/Th1-like effector states while regulatory T-cell restraint is insufficient. This cytokine circuit recruits and activates macrophages, promotes epithelioid and multinucleated giant-cell granuloma architecture, and intersects with macrophage-intrinsic metabolic programs such as mTORC1 activation. Resolution is hypothesized to require antigen clearance or sequestration plus restoration of regulatory and apoptotic checkpoints; chronic disease and fibrosis occur when antigen persistence, Th17.1 feedback, macrophage survival/proliferation, and tissue-repair programs remain engaged.

Retained as EMERGING after the 2026 OpenScientist hypothesis-search report (kb/hypotheses/Sarcoidosis/antigen_persistence_granuloma_chronicity_model/openscientist.md). The report judged the model partially supported: antigen-driven CD4 T-cell responses, Th17.1/Treg imbalance, and macrophage mTORC1 granuloma biology are individually well supported, but the integrated Th17.1-to-macrophage mTORC1 link remains unproven and fibrosis may diverge through distinct profibrotic/EMT-like tissue-remodeling programs. Best current fit is non-Lofgren, chronic/progressive pulmonary sarcoidosis rather than all sarcoidosis phenotypes.

Pathograph links

Genetic Susceptibility -> Antigen Recognition and CD4+ T-Cell Activation DIRECT Risk alleles in HLA-DRB1 and BTNL2 alter MHC class II antigen presentation and T-cell co-inhibition, lowering the threshold for an exaggerated CD4+ T-cell response to a triggering antigen.

Antigen Recognition and CD4+ T-Cell Activation -> Th17.1 Polarization and IFN-gamma Production DIRECT Antigen-activated CD4+ T cells in lung tissue polarize toward an IFN-gamma-producing Th17.1 phenotype that drives sustained granulomatous inflammation.

Th17.1 Polarization and IFN-gamma Production -> Macrophage Activation and mTORC1 Hyperactivation INDIRECT UNKNOWN INTERMEDIATES IFN-gamma-rich Th17.1 inflammation, persistent antigen, and other tissue signals are hypothesized to converge on recruitment, activation, and metabolic reprogramming of macrophages; direct Th17.1-to-macrophage mTORC1 causality in human sarcoidosis remains unproven. Intermediates: Unresolved coupling between Th17.1 cytokines, persistent antigen, macrophage growth/survival signals, and macrophage mTORC1 activation.

Macrophage Activation and mTORC1 Hyperactivation -> Granuloma Formation DIRECT mTORC1-driven hypertrophic, proliferating macrophages aggregate with multinucleated giant cells and CD4+ T cells to form non-caseating granulomas.

Granuloma Formation -> Fibrotic Tissue Remodeling INDIRECT UNKNOWN INTERMEDIATES Persistent granulomatous inflammation is associated with later TGF-beta-driven myofibroblast programs and excessive ECM deposition in a subset of patients, but the switch from active granulomas to fibrotic remodeling is not resolved and may involve partly distinct profibrotic pathways. Intermediates: Unresolved granuloma-to-fibrosis switch involving TGF-beta signaling, epithelial-mesenchymal transition-like programs, fibroblast activation, and chronic tissue injury.

Deep research

OpenScientist citations 44 citations 2026-06-03T11:40:50.280377

Show evidence (2 references)

PMID:38165044 SUPPORT Human Clinical

"Sarcoidosis is a complex immune-mediated disease characterized by clusters of immune cells called granulomas."

Recent mechanistic review used as the seed reference for the hypothesis-search deep-research run and for the antigen/T-cell/macrophage granuloma-chronicity framing.

PMID:31273209 SUPPORT Human Clinical

"The disease develops in genetically predisposed individuals with exposure to an as-yet unknown antigen."

Nature Reviews Disease Primers review supports the central upstream premise of this hypothesis: genetically predisposed patients encounter an unknown antigenic trigger.

Discussions and Knowledge Gaps

Which antigenic triggers and host immune-cell circuits determine whether a sarcoidosis granuloma resolves, persists as chronic inflammatory disease, or transitions to fibrotic organ damage?

KNOWLEDGE GAP OPEN gap_sarcoidosis_antigen_persistence_resolution

Attached to

pathophysiology#Antigen Recognition and CD4+ T-Cell Activation pathophysiology#Th17.1 Polarization and IFN-gamma Production pathophysiology#Macrophage Activation and mTORC1 Hyperactivation pathophysiology#Granuloma Formation pathophysiology#Fibrotic Tissue Remodeling

The entry captures a plausible antigen-driven CD4 T-cell, Th17.1, Treg, macrophage, and mTORC1 cascade, but the disease-defining upstream antigen remains unknown and the switch from spontaneous resolution to chronic granuloma persistence or fibrosis is not causally resolved. This matters because current treatment suppresses granulomatous inflammation after organ dysfunction appears; it does not yet stratify patients by antigen source, antigen clearance, granuloma metabolic state, or fibrotic transition risk.

Proposed experiments

Longitudinal sarcoidosis granuloma antigen and resolution map

longitudinal human granuloma perturbation experiment

exp_sarcoidosis_longitudinal_granuloma_resolution_map

Profile newly diagnosed sarcoidosis patients with paired bronchoalveolar lavage, blood, and when clinically obtained granuloma biopsies at diagnosis and follow-up. Combine antigen discovery (mycobacterial/propionibacterial/environmental peptide and nucleic-acid panels), TCR clonotype tracking, spatial single-cell transcriptomics, and perturbation of patient-derived macrophage/T-cell cultures with antigen withdrawal, Treg-restoring conditions, IFN-gamma/JAK blockade, and mTORC1 inhibition. Compare patients who spontaneously remit with those who develop chronic pulmonary disease or fibrosis.

Model systems

Patient-derived pulmonary sarcoidosis immune-cell culture

Paired bronchoalveolar lavage and biopsy-derived macrophage-lineage cells, CD4+ T cells, and fibroblast-containing granuloma explant or coculture systems from remitting and chronic/progressive sarcoidosis patients.

PRIMARY CELL CULTURE

human NCBITaxon:9606

lung UBERON:0002048

alveolar macrophage CL:0000583 CD4-positive helper T cell CL:0000492 fibroblast CL:0000057

Perturbations

Antigen candidate exposure and withdrawal

pathophysiology#Antigen Recognition and CD4+ T-Cell Activation

Test whether candidate microbial, self, or environmental antigens maintain TCR clonotype activation and granuloma-like organization, and whether withdrawal collapses the inflammatory program.

Effect: antigen presence versus clearance

mTORC1 and IFN-gamma/JAK pathway blockade

pathophysiology#Macrophage Activation and mTORC1 Hyperactivation

Compare rapamycin/everolimus-like mTORC1 inhibition and JAK blockade for their ability to induce macrophage apoptosis, reduce glycolytic granuloma-state markers, and interrupt Th17.1-macrophage feedback.

Effect: decreased granuloma persistence signaling

Readouts

Antigen-specific TCR clonotype persistence

pathophysiology#Antigen Recognition and CD4+ T-Cell Activation

Persistence or contraction of antigen-reactive CD4+ T-cell clonotypes over time and after antigen withdrawal in culture.

Progressive macrophage metabolic state

pathophysiology#Macrophage Activation and mTORC1 Hyperactivation

p-S6, Ki-67, glycolysis, and apoptosis readouts that distinguish remitting from chronic/progressive granuloma macrophages.

Fibrotic transition signal

pathophysiology#Fibrotic Tissue Remodeling

Spatial TGF-beta signaling, fibroblast activation, extracellular matrix organization, and pulmonary-function trajectory used to determine whether persistent granuloma circuits predict fibrotic organ damage.

Decision criterion

The antigen-persistence model would be strengthened if remitting patients show antigen-reactive clonotype contraction and loss of macrophage mTORC1/glycolytic signals, while chronic or fibrotic patients retain antigen-reactive clonotypes, Th17.1/Treg imbalance, macrophage p-S6/Ki-67 activity, and fibroblast activation despite standard immunosuppression.

Show evidence (3 references)

PMID:31273209 SUPPORT Human Clinical

"The disease develops in genetically predisposed individuals with exposure to an as-yet unknown antigen."

Establishes unknown antigen identity as a central unresolved upstream causal step.

PMID:33329511 SUPPORT Human Clinical

"Over half of patients with sarcoidosis will incur spontaneous resolution or never have clinical manifestations of the disease, whereas the remaining half will experience a more chronic course, often requiring treatment."

Supports the resolution-versus-chronicity split that the proposed longitudinal experiment is designed to distinguish.

PMID:38165044 SUPPORT Human Clinical

"Despite major steps in understanding the cause of this disease, many questions remain."

Recent mechanistic review explicitly frames granuloma-cause and granuloma-mechanism uncertainty as an active knowledge gap.

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Pathophysiology

Genetic Susceptibility

Sarcoidosis is a polygenic immune disorder. Risk-associated variants in HLA class II (DRB1 lineages), the truncating splice variant rs2076530 in BTNL2 (a T-cell co-inhibitory butyrophilin-like immunoglobulin superfamily member), the missense ANXA11 R230C (rs1049550), NOTCH4, and IL27RA collectively shift antigen presentation, T-cell co-stimulation/inhibition, and macrophage apoptosis thresholds, predisposing to exaggerated granulomatous response on antigen encounter.

Antigen Persistence / Th17.1 / mTORC1 Granuloma Chronicity Model

CD4-positive helper T cell CL:0000492

antigen processing and presentation GO:0019882

Downstream

Antigen Recognition and CD4+ T-Cell Activation Risk alleles in HLA-DRB1 and BTNL2 alter MHC class II antigen presentation and T-cell co-inhibition, lowering the threshold for an exaggerated CD4+ T-cell response to a triggering antigen.

Show evidence (3 references)

PMID:15735647 SUPPORT Human Clinical

"The G --> A transition constituting rs2076530 leads to the use of a cryptic splice site located 4 bp upstream of the affected wild-type donor site. Transcripts of the risk-associated allele have a premature stop in the spliced mRNA. The resulting protein lacks the C-terminal IgC domain and..."

This case-control SNP scan identifies the truncating BTNL2 splice variant rs2076530 as a sarcoidosis risk factor independent of HLA-DRB1, with a defined molecular consequence (loss of membrane-anchored co-inhibitory protein).

PMID:19165924 SUPPORT Human Clinical

"The strongest association signal maps to the ANXA11 (annexin A11) gene on chromosome 10q22.3."

GWAS plus replication establishes ANXA11 as a major sarcoidosis susceptibility locus; the lead missense R230C (rs1049550) variant defined in this work is the molecular entry point for the apoptosis/proliferation arm of the pathograph.

PMID:19165924 PARTIAL Human Clinical

"Annexin A11 has complex and essential functions in several biological pathways, including apoptosis and proliferation."

Functional context for why ANXA11 risk variants are mechanistically relevant - the gene regulates apoptosis and proliferation, which are precisely the macrophage processes dysregulated in granuloma maintenance.

Antigen Recognition and CD4+ T-Cell Activation

Susceptibility alleles allow MHC class II presentation of poorly degradable antigens (mycobacterial KatG, ESAT-6, Ag85A, sodA, HSP; propionibacterial proteins; or environmental particulates) to CD4+ T cells, which expand clonally and acquire a Th1/Th17.1 effector program with high IFN-gamma production.

Antigen Persistence / Th17.1 / mTORC1 Granuloma Chronicity Model

CD4-positive helper T cell CL:0000492 alveolar macrophage CL:0000583

antigen processing and presentation of peptide antigen via MHC class II GO:0002495 T cell activation GO:0042110

Downstream

Th17.1 Polarization and IFN-gamma Production Antigen-activated CD4+ T cells in lung tissue polarize toward an IFN-gamma-producing Th17.1 phenotype that drives sustained granulomatous inflammation.

Show evidence (2 references)

PMID:21092305 SUPPORT Human Clinical

"Alveolar T-cells from twenty-two of the 31 sarcoidosis patients produced a CD4+ response to at least one of ESAT-6, katG, Ag85A, sodA, or HSP, compared to two of 14 PPD- controls (p = 0.0008)"

Direct demonstration that lung-resident T cells from sarcoidosis patients recognize mycobacterial antigens, supporting an antigen-driven step linking the susceptibility node to T-cell activation.

PMID:31273209 SUPPORT Human Clinical

"The typical T cell accumulation, local T cell immune response and granuloma formation in the lungs indicate that the inflammatory response in sarcoidosis is induced by specific antigens, possibly including self-antigens, which is consistent with an autoimmune involvement."

Review-level synthesis supports antigen-driven local T-cell responses in pulmonary sarcoidosis while preserving uncertainty about antigen identity.

Th17.1 Polarization and IFN-gamma Production

Plasticity within the Th17 lineage produces IFN-gamma-producing Th17.1 cells that are the dominant source of IFN-gamma in pulmonary sarcoidosis and correlate with progressive (non-Lofgren) disease. Concurrent Treg dysfunction (impaired survival, altered CTLA-4 expression) removes the brake on this effector response.

Antigen Persistence / Th17.1 / mTORC1 Granuloma Chronicity Model

T-helper 17 cell CL:0000899 regulatory T cell CL:0000815

T-helper 17 type immune response GO:0072538 regulatory T cell apoptotic process GO:1902482

Downstream

Macrophage Activation and mTORC1 Hyperactivation IFN-gamma-rich Th17.1 inflammation, persistent antigen, and other tissue signals are hypothesized to converge on recruitment, activation, and metabolic reprogramming of macrophages; direct Th17.1-to-macrophage mTORC1 causality in human sarcoidosis remains unproven.

Show evidence (4 references)

PMID:27379969 SUPPORT Human Clinical

"it was demonstrated that Th17.1-cells rather than Th1-cells are responsible for the exaggerated IFN-γ production in pulmonary sarcoidosis."

Reviews the paradigm shift identifying Th17.1 cells (not classical Th1) as the dominant IFN-gamma source in sarcoidosis, anchoring this node mechanistically.

PMID:29310925 SUPPORT Human Clinical

"In non-LS sarcoidosis patients, IFN-γ-producing Th17.1-cells appear to be more pathogenic and possibly linked to disease progression"

Direct support that Th17.1 polarization marks the pathogenic, progression-prone arm of sarcoidosis and is the upstream effector that drives macrophage transformation.

PMID:24882950 SUPPORT Human Clinical

"The proportion of Th17 cells positive for IFN-gamma was greater in sarcoidosis than controls (median 72.4% versus 31%, P = 0.0005) and increased with radiologic stage (N = 23, rho = 0.45, and P = 0.03)."

Quantitative evidence that the IFN-gamma+ Th17 (Th17.1) compartment is enriched in lung lavage of sarcoidosis patients and tracks with radiographic stage.

+ 1 more reference

Macrophage Activation and mTORC1 Hyperactivation

Chronic antigenic stimulation drives macrophage hypertrophy, proliferation, and transformation into epithelioid cells. A macrophage-intrinsic increase in mTORC1 signaling (genetically modeled by Tsc2 deletion) is sufficient to initiate and sustain non-caseating granulomas, via CDK4-dependent proliferation, glycolytic reprogramming, and suppression of macrophage apoptosis. mTORC1 activation is enriched in progressive human sarcoidosis lesions.

Antigen Persistence / Th17.1 / mTORC1 Granuloma Chronicity Model

epithelioid macrophage CL:0002150 macrophage CL:0000235

TORC1 signaling GO:0038202 ↑ INCREASED macrophage activation GO:0042116 glycolytic process GO:0006096 ↑ INCREASED negative regulation of macrophage apoptotic process GO:2000110

Downstream

Granuloma Formation mTORC1-driven hypertrophic, proliferating macrophages aggregate with multinucleated giant cells and CD4+ T cells to form non-caseating granulomas.

Show evidence (3 references)

PMID:28092373 SUPPORT Model Organism

"We found that activation of the metabolic checkpoint kinase mTORC1 in macrophages by deletion of the gene encoding tuberous sclerosis 2 (Tsc2) was sufficient to induce hypertrophy and proliferation, resulting in excessive granuloma formation in vivo."

Conditional Tsc2 deletion in mouse myeloid cells is sufficient to recapitulate sarcoid-like granulomas, mechanistically anchoring macrophage-intrinsic mTORC1 hyperactivation as a granuloma-initiating step.

PMID:28092373 SUPPORT Human Clinical

"In human sarcoidosis patients, mTORC1 activation, macrophage proliferation and glycolysis were identified as hallmarks that correlated with clinical disease progression."

Re-analysis of human sarcoidosis biopsies translates the mouse mechanism - mTORC1 activity, macrophage proliferation, and glycolysis distinguish progressive from self-limiting disease in patients.

PMID:29104468 PARTIAL Human Clinical

"Disturbance of T memory cells, Th1/Th2, and Tregs/Th17 cells, and activation of PI3K/Akt signaling were seen in newly diagnosed stage II pulmonary sarcoidosis"

Independent confirmation that PI3K/Akt (upstream of mTORC1) is activated in pulmonary sarcoidosis BAL cells, supporting parallel relevance of this metabolic axis in human disease.

Granuloma Formation

Non-caseating granulomas consist of organized collections of activated macrophages (epithelioid cells), multinucleated giant cells, and CD4+ T cells. Th1/Th17.1 immune responses drive granuloma development in response to persistent antigens. Granulomas are the defining histopathologic lesion that mediates the downstream organ-level phenotypes of sarcoidosis.

Antigen Persistence / Th17.1 / mTORC1 Granuloma Chronicity Model

epithelioid macrophage CL:0002150 multinucleated giant cell CL:0000647 CD4-positive helper T cell CL:0000492

granuloma formation GO:0002432

Downstream

Macrophage Calcitriol Production Granuloma macrophages express CYP27B1 and convert 25-hydroxyvitamin D to active 1,25-dihydroxyvitamin D outside normal renal regulation, predisposing to hypercalcemia.

Macrophage ACE Production Epithelioid macrophages within granulomas synthesize angiotensin-converting enzyme, producing the elevated serum ACE characteristic of active sarcoidosis.

Fibrotic Tissue Remodeling Persistent granulomatous inflammation is associated with later TGF-beta-driven myofibroblast programs and excessive ECM deposition in a subset of patients, but the switch from active granulomas to fibrotic remodeling is not resolved and may involve partly distinct profibrotic pathways.

Show evidence (3 references)

PMID:35011621 PARTIAL Human Clinical

"Sarcoidosis is a chameleon disease of unknown etiology, characterized by the growth of non-necrotizing and non-caseating granulomas"

This review confirms the characteristic non-caseating granuloma formation in sarcoidosis.

PMID:38165044 SUPPORT Human Clinical

"Sarcoidosis is a complex immune-mediated disease characterized by clusters of immune cells called granulomas."

This 2024 JCI mechanistic review frames sarcoidosis as a granuloma-defined immune-mediated disease and is the source for the integrated antigen-T-cell-macrophage causal chain summarized here.

PMID:33329511 SUPPORT Human Clinical

"The sarcoidosis granuloma is formed by a distinct conglomeration of multinucleated giant cells and epithelioid macrophages surrounded by a rim of CD4+ T cells"

Full-text review-level support for the core immune-cell architecture of sarcoid granulomas: macrophage-lineage giant/epithelioid cells surrounded by CD4+ T cells.

Macrophage Calcitriol Production

Activated monocytes and macrophages within sarcoid granulomas express 1-alpha-hydroxylase (CYP27B1), converting 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D outside normal PTH/FGF23 regulation. This extrarenal calcitriol synthesis, with optional PTHrP secretion, drives intestinal calcium absorption and bone resorption, producing hypercalcemia and hypercalciuria.

macrophage CL:0000235

vitamin D metabolic process GO:0042359 ↑ INCREASED

Downstream

Hypercalcemia Extrarenal 1,25-dihydroxyvitamin D production by granuloma macrophages causes hypercalcemia in approximately 5-10% of patients.

Show evidence (2 references)

PMID:24663253 SUPPORT Human Clinical

"Hypercalcemia in sarcoidosis is due to three mechanistic reasons: (1) systemic conversion of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D by the enzyme 1-alpha hydroxylase produced by activated monocyte/macrophage system, (2) production of parathormone-related peptide (PTHrP) by the sarcoid..."

Mechanistic case-based report explicitly attributing sarcoid hypercalcemia to macrophage-driven extrarenal CYP27B1 expression and PTHrP, defining the molecular bridge from granuloma to the hypercalcemia phenotype.

PMID:23337133 SUPPORT Human Clinical

"Hypercalcemia associated with mineral oil induced skin lesions is likely driven by unregulated expression of CYP27b1 by inflammatory monocytes and macrophages infiltrating the dermis."

A non-sarcoidosis granulomatous condition independently demonstrates that ectopic CYP27B1 expression in tissue macrophages causes hypercalcemia, generalizing the macrophage-calcitriol mechanism.

Macrophage ACE Production

Epithelioid macrophages within granulomas constitutively express angiotensin-converting enzyme (ACE), and serum ACE elevation reflects total granuloma burden. Single-cell RNA-seq of cutaneous sarcoid granulomas has identified TREM2-positive ACE-expressing macrophages as a granuloma-resident population, supporting macrophage origin of the serum biomarker.

epithelioid macrophage CL:0002150

Downstream

Elevated ACE Granuloma-resident epithelioid macrophages secrete ACE; circulating levels are raised in active sarcoidosis and broadly correlate with granuloma burden.

Show evidence (1 reference)

PMID:38038136 SUPPORT Human Clinical

"the percentages of triggering receptor expressed on myeloid cells 2-positive (TREM2-positive) macrophages expressing angiotensin-converting enzyme (ACE) and lysozyme, diagnostic makers of sarcoidosis, were increased in cutaneous sarcoidosis granulomas."

Single-cell RNA-seq demonstrates TREM2+ macrophages expressing ACE are enriched in sarcoid granulomas, directly supporting the macrophage origin of serum ACE elevation.

Fibrotic Tissue Remodeling

In approximately 10-30% of patients with chronic disease, persistent granulomatous inflammation transitions to a profibrotic state characterized by TGF-beta signaling, fibroblast/myofibroblast activation, and excessive extracellular matrix deposition. The end result is irreversible parenchymal fibrosis with restrictive physiology, fibrocystic remodeling, and respiratory failure. This node conforms to the conserved fibrotic response module.

fibroblast CL:0000057

extracellular matrix organization GO:0030198 ↑ INCREASED

Downstream

Pulmonary Fibrosis Persistent granulomatous inflammation drives ECM deposition, restrictive physiology, and irreversible fibrocystic remodeling in 10-30% of patients.

Show evidence (1 reference)

PMID:41095908 SUPPORT Human Clinical

"Although many patients experience spontaneous remission, approximately 10-30% develop progressive pulmonary disease, which may lead to fibrocystic changes, respiratory failure, and death."

This review directly supports progression from pulmonary sarcoidosis to fibrocystic and fibrotic lung disease in a substantial subset of patients.

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Pathograph

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

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Phenotypes

Blood 2

Thrombocytopenia FREQUENT Thrombocytopenia HP:0001873

Show evidence (1 reference)

ORPHA:797 SUPPORT Other

"HP:0001873 | Thrombocytopenia | Frequent (79-30%)"

Orphanet records thrombocytopenia as a frequent (30-79%) phenotype of sarcoidosis.

Leukopenia FREQUENT Decreased total leukocyte count HP:0001882

Show evidence (1 reference)

ORPHA:797 SUPPORT Other

"HP:0001882 | Leukopenia | Frequent (79-30%)"

Orphanet records leukopenia as a frequent (30-79%) phenotype of sarcoidosis.

Cardiovascular 8

Mediastinal Lymphadenopathy VERY_FREQUENT Mediastinal lymphadenopathy HP:0100721

Show evidence (1 reference)

PMID:31485575 PARTIAL Human Clinical

"Although intrathoracic involvement is the hallmark of the disease, present in over 90% of patients, sarcoidosis can affect virtually any organ."

This Mayo Clinic review strongly supports intrathoracic involvement as the dominant manifestation of sarcoidosis, but only indirectly supports mediastinal lymphadenopathy specifically.

Atrioventricular Block OCCASIONAL Atrioventricular block HP:0001678

Show evidence (1 reference)

PMID:39621157 SUPPORT Human Clinical

"male gender, a QRS duration > 120 ms, and nsVT on Holter monitoring were identified as significant markers associated with the presence of cardiac sarcoidosis"

Cohort screening study supports conduction abnormalities (QRS >120 ms, including AV block) as defining cardiac sarcoidosis features.

Ventricular Arrhythmia OCCASIONAL Ventricular arrhythmia HP:0004308

Show evidence (1 reference)

PMID:39621157 SUPPORT Human Clinical

"Early detection of cardiac sarcoidosis (CS) is crucial due to its association with severe complications such as ventricular arrhythmias, heart failure, and sudden cardiac death."

Directly supports ventricular arrhythmia as a recognized cardiac sarcoidosis complication.

Sudden Cardiac Death OCCASIONAL Sudden cardiac death HP:0001645

Show evidence (1 reference)

PMID:39621157 SUPPORT Human Clinical

"Early detection of cardiac sarcoidosis (CS) is crucial due to its association with severe complications such as ventricular arrhythmias, heart failure, and sudden cardiac death."

Directly supports sudden cardiac death as a severe sarcoidosis complication driven by myocardial granulomatous involvement.

Hepatosplenomegaly OCCASIONAL Hepatosplenomegaly HP:0001433

Show evidence (2 references)

PMID:30305603 SUPPORT Human Clinical

"The majority of patients with hepatic sarcoidosis are usually asymptomatic, with only 5-30% presenting with abdominal pain, jaundice, nausea, vomiting, and hepatosplenomegaly."

Directly supports hepatosplenomegaly as a clinical manifestation of hepatic sarcoidosis occurring in 5-30% of affected patients.

PMID:11734441 SUPPORT Human Clinical

"Black subjects were more likely to have skin involvement other than erythema nodosum (chi(2) = 5.47, p < 0.05), and eye (chi(2) = 13.8, p < 0.0001), liver (chi(2) = 23.3, p < 0.0001), bone marrow (chi(2) = 18.8, p < 0.001), and extrathoracic lymph node involvement (chi(2) = 7.21, p < 0.01)."

ACCESS cohort demonstrates liver involvement as a recognized organ manifestation of sarcoidosis with racial differences in frequency.

Splenomegaly OCCASIONAL Splenomegaly HP:0001744

Show evidence (1 reference)

PMID:30305603 SUPPORT Human Clinical

"The majority of patients with hepatic sarcoidosis are usually asymptomatic, with only 5-30% presenting with abdominal pain, jaundice, nausea, vomiting, and hepatosplenomegaly."

Hepatosplenomegaly directly supports splenomegaly as a clinical manifestation in hepatic sarcoidosis patients.

Peripheral Lymphadenopathy OCCASIONAL Lymphadenopathy HP:0002716

Show evidence (2 references)

PMID:11734441 SUPPORT Human Clinical

ACCESS cohort study directly demonstrates extrathoracic lymph node involvement as a recognized manifestation of sarcoidosis.

ORPHA:797 SUPPORT

"peripheral lymph nodes, fatigue, weight loss, fever or night sweats"

Orphanet definition lists peripheral lymph nodes as a typical presentation feature.

Heart Failure OCCASIONAL Congestive heart failure HP:0001635

Show evidence (2 references)

PMID:39621157 SUPPORT Human Clinical

"Early detection of cardiac sarcoidosis (CS) is crucial due to its association with severe complications such as ventricular arrhythmias, heart failure, and sudden cardiac death."

Heart failure directly supported as a severe complication of cardiac sarcoidosis.

PMID:27454307 SUPPORT Human Clinical

"arrhythmias and heart failure in cardiac sarcoidosis"

Heart failure confirmed as an organ-specific manifestation of cardiac sarcoidosis.

Digestive 1

Decreased liver function FREQUENT Decreased liver function HP:0001410

Show evidence (1 reference)

ORPHA:797 SUPPORT Other

"HP:0001410 | Decreased liver function | Frequent (79-30%)"

Orphanet records decreased liver function as a frequent (30-79%) phenotype of sarcoidosis.

Endocrine 1

Diabetes insipidus OCCASIONAL Diabetes insipidus HP:0000873

Show evidence (1 reference)

ORPHA:797 SUPPORT Other

"HP:0000873 | Diabetes insipidus | Occasional (29-5%)"

Orphanet records diabetes insipidus as an occasional (5-29%) phenotype of sarcoidosis.

Eye 4

Uveitis OCCASIONAL Uveitis HP:0000554

Show evidence (1 reference)

PMID:33173272 SUPPORT Human Clinical

"Uveitis was the most common ocular manifestation."

This retrospective series directly supports uveitis as a common ocular manifestation among patients with ocular sarcoidosis.

Glaucoma OCCASIONAL Glaucoma HP:0000501

Show evidence (1 reference)

ORPHA:797 SUPPORT Other

"HP:0000501 | Glaucoma | Occasional (29-5%)"

Orphanet records glaucoma as an occasional (5-29%) phenotype of sarcoidosis.

Cataract OCCASIONAL Cataract HP:0000518

Show evidence (1 reference)

ORPHA:797 SUPPORT Other

"HP:0000518 | Cataract | Occasional (29-5%)"

Orphanet records cataract as an occasional (5-29%) phenotype of sarcoidosis.

Blindness OCCASIONAL Blindness HP:0000618

Show evidence (1 reference)

ORPHA:797 SUPPORT Other

"HP:0000618 | Blindness | Occasional (29-5%)"

Orphanet records blindness as an occasional (5-29%) phenotype of sarcoidosis.

Genitourinary 2

Renal insufficiency OCCASIONAL Renal insufficiency HP:0000083

Show evidence (1 reference)

ORPHA:797 SUPPORT Other

"HP:0000083 | Renal insufficiency | Occasional (29-5%)"

Orphanet records renal insufficiency as an occasional (5-29%) phenotype of sarcoidosis.

Nephrolithiasis OCCASIONAL Nephrolithiasis HP:0000787

Show evidence (1 reference)

ORPHA:797 SUPPORT Other

"HP:0000787 | Nephrolithiasis | Occasional (29-5%)"

Orphanet records nephrolithiasis as an occasional (5-29%) phenotype of sarcoidosis.

Head and Neck 2

Facial Palsy OCCASIONAL Facial palsy HP:0010628

Show evidence (1 reference)

PMID:33110001 PARTIAL Human Clinical

"Sarcoidosis is an idiopathic, multisystem, inflammatory disease that has central nervous system involvement in 5%-15% of cases."

Establishes CNS involvement frequency in sarcoidosis; cranial neuropathies including facial palsy are recognized presenting features.

Dacryocystitis OCCASIONAL Dacryocystitis HP:0000620

Show evidence (1 reference)

ORPHA:797 SUPPORT Other

"HP:0000620 | Dacryocystitis | Occasional (29-5%)"

Orphanet records dacryocystitis as an occasional (5-29%) phenotype of sarcoidosis.

Immune 1

Erythema Nodosum OCCASIONAL Erythema nodosum HP:0012219

Show evidence (1 reference)

PMID:39082153 SUPPORT Human Clinical

"Löfgren syndrome (LS) is a sarcoidosis subtype characterised by an acute disease course, bilateral hilar lymphadenopathy (BHL), erythema nodosum (EN), and ankle arthritis."

This review of Lofgren syndrome directly supports erythema nodosum as a recognized acute cutaneous manifestation of sarcoidosis.

Integument 3

Lupus Pernio OCCASIONAL Skin plaque HP:0200035

Course: PROGRESSIVE

Show evidence (1 reference)

PMID:30555667 SUPPORT Human Clinical

"LP is a rare presentation with infiltrated erythematoviolaceous plaques affecting the nose."

This case report and literature review directly identifies lupus pernio as a cutaneous sarcoidosis manifestation characterized by infiltrated violaceous plaques.

Skin nodule FREQUENT Skin nodule HP:0200036

Show evidence (1 reference)

ORPHA:797 SUPPORT Other

"HP:0200036 | Skin nodule | Frequent (79-30%)"

Orphanet records skin nodule as a frequent (30-79%) phenotype of sarcoidosis.

Hyperpigmentation of the skin OCCASIONAL Hyperpigmentation of the skin HP:0000953

Show evidence (1 reference)

ORPHA:797 SUPPORT Other

"HP:0000953 | Hyperpigmentation of the skin | Occasional (29-5%)"

Orphanet records hyperpigmentation of the skin as an occasional (5-29%) phenotype of sarcoidosis.

Metabolism 4

Hypercalcemia OCCASIONAL Hypercalcemia HP:0003072

Show evidence (1 reference)

PMID:24663253 SUPPORT Human Clinical

Directly supports hypercalcemia as a phenotype of sarcoidosis with a defined macrophage-CYP27B1 mechanism.

Fever OCCASIONAL Fever HP:0001945

Show evidence (2 references)

PMID:38227868 SUPPORT Human Clinical

"Patients with sarcoidosis can exhibit constitutional symptoms such as fever, unintentional weight loss, and fatigue."

Fever listed as a recognized constitutional symptom of sarcoidosis.

ORPHA:797 SUPPORT

"Clinical presentation is typically with persistent dry cough, eye or skin manifestations, peripheral lymph nodes, fatigue, weight loss, fever or night sweats, and Löfgren syndrome."

Orphanet definition includes fever as a typical clinical presentation feature.

Joint swelling FREQUENT Joint swelling HP:0001386

Show evidence (1 reference)

ORPHA:797 SUPPORT Other

"HP:0001386 | Joint swelling | Frequent (79-30%)"

Orphanet records joint swelling as a frequent (30-79%) phenotype of sarcoidosis.

Pleural effusion FREQUENT Pleural effusion HP:0002202

Show evidence (1 reference)

ORPHA:797 SUPPORT Other

"HP:0002202 | Pleural effusion | Frequent (79-30%)"

Orphanet records pleural effusion as a frequent (30-79%) phenotype of sarcoidosis.

Nervous System 1

Small Fiber Neuropathy FREQUENT Peripheral neuropathy HP:0009830

Show evidence (2 references)

PMID:39291161 SUPPORT Human Clinical

"Small fiber neuropathy is a common complication in patients with sarcoidosis and its prevalence is estimated at 40-86%."

Establishes small fiber neuropathy as a highly prevalent complication of sarcoidosis.

PMID:24090799 SUPPORT Human Clinical

"Recognition of unexplained persistent disabling symptoms, fatigue, small-fibre neurological impairment, cognitive failure, and changes to health state and quality of life, has improved."

Lancet review recognizes small-fiber neurological impairment as an important persistent disabling symptom of sarcoidosis.

Respiratory 4

Dyspnea FREQUENT Dyspnea HP:0002094

Show evidence (1 reference)

PMID:38227868 SUPPORT Human Clinical

"Ongoing dyspnea and dry cough in a young to middle-aged adult should increase the suspicion for sarcoidosis."

This 2024 American Family Physician review identifies dyspnea as a key presenting symptom that should raise suspicion for sarcoidosis.

Nonproductive Cough FREQUENT Nonproductive cough HP:0031246

Show evidence (1 reference)

PMID:38227868 SUPPORT Human Clinical

"Ongoing dyspnea and dry cough in a young to middle-aged adult should increase the suspicion for sarcoidosis."

Dry cough is identified as a hallmark symptom that should raise clinical suspicion for sarcoidosis in younger adults.

Pulmonary Fibrosis OCCASIONAL Pulmonary fibrosis HP:0002206

Course: PROGRESSIVE

Show evidence (1 reference)

PMID:41095908 SUPPORT Human Clinical

"Although many patients experience spontaneous remission, approximately 10-30% develop progressive pulmonary disease, which may lead to fibrocystic changes, respiratory failure, and death."

Directly supports pulmonary fibrosis as a progression-related phenotype occurring in a substantial subset of sarcoidosis patients.

Cough FREQUENT Cough HP:0012735

Show evidence (1 reference)

ORPHA:797 SUPPORT Other

"HP:0012735 | Cough | Frequent (79-30%)"

Orphanet records cough as a frequent (30-79%) phenotype of sarcoidosis.

Constitutional 4

Fatigue FREQUENT Fatigue HP:0012378

Show evidence (1 reference)

PMID:38227868 PARTIAL Human Clinical

"Patients with sarcoidosis can exhibit constitutional symptoms such as fever, unintentional weight loss, and fatigue."

This review supports fatigue as a recognized constitutional symptom in sarcoidosis, but the wording is not strong enough on its own to justify a VERY_FREQUENT frequency assignment.

Arthralgia FREQUENT Arthralgia HP:0002829

Show evidence (2 references)

PMID:38281070 SUPPORT Human Clinical

"The PPE for sarcoid arthritis (SA) was 19% (95% CI 14, 24; I2 = 95%), and 32% (95% CI 13, 51; I2 = 99%) for arthralgia."

Systematic review and meta-analysis of 49 studies (8574 patients) establishes arthralgia pooled prevalence at 32% and sarcoid arthritis at 19%.

PMID:27454307 SUPPORT Human Clinical

"Systemic symptoms include fatigue, night sweats, weight loss, fever, arthralgia and myalgia."

Epidemiologic review listing arthralgia as a recognized systemic symptom of sarcoidosis.

Night Sweats OCCASIONAL Night sweats HP:0030166

Show evidence (2 references)

PMID:27454307 SUPPORT Human Clinical

"Systemic symptoms include fatigue, night sweats, weight loss, fever, arthralgia and myalgia."

Night sweats listed among systemic symptoms of sarcoidosis.

ORPHA:797 SUPPORT

"fatigue, weight loss, fever or night sweats, and Löfgren syndrome."

Orphanet definition includes night sweats in typical presentation.

Chest Pain FREQUENT Chest pain HP:0100749

Show evidence (1 reference)

PMID:31273209 SUPPORT Human Clinical

"Patients frequently suffer from cough, shortness of breath, chest pain and pronounced fatigue"

Nature Reviews Disease Primers identifies chest pain as a frequent symptom of sarcoidosis.

Growth 1

Weight Loss OCCASIONAL Weight loss HP:0001824

Show evidence (2 references)

PMID:38227868 SUPPORT Human Clinical

"Patients with sarcoidosis can exhibit constitutional symptoms such as fever, unintentional weight loss, and fatigue."

Weight loss identified as a constitutional symptom of sarcoidosis.

ORPHA:797 SUPPORT

"Clinical presentation is typically with persistent dry cough, eye or skin manifestations, peripheral lymph nodes, fatigue, weight loss, fever or night sweats, and Löfgren syndrome."

Orphanet definition lists weight loss as a typical presentation feature.

Other 2

Nephrocalcinosis OCCASIONAL Nephrocalcinosis HP:0000121

Show evidence (1 reference)

PMID:35436276 SUPPORT Human Clinical

"Renal involvement is observed in 30% of sarcoidosis cases, but the exact occurrence is unknown, and the current numbers are estimated to be underestimated."

Confirms renal involvement prevalence and identifies nephrocalcinosis as a common renal manifestation of sarcoidosis.

Increased T cell count FREQUENT Increased total T cell count HP:0100828

Show evidence (1 reference)

ORPHA:797 SUPPORT Other

"HP:0100828 | Increased T cell count | Frequent (79-30%)"

Orphanet records increased T cell count as a frequent (30-79%) phenotype of sarcoidosis.

🧬

Genetic Associations

HLA-DRB1 Variants (Susceptibility)

Gene: HLA-DRB1 hgnc:4948

Show evidence (1 reference)

PMID:25506722 SUPPORT Human Clinical

"This study has identified DRB1*03:01 and *03:02 as novel alleles associated with disease susceptibility and course in African Americans."

This large genetic association study directly supports HLA-DRB1 variation as a determinant of sarcoidosis susceptibility and clinical course.

BTNL2 Variants (Susceptibility)

Gene: BTNL2 hgnc:1142

Show evidence (2 references)

PMID:21410903 SUPPORT Human Clinical

"The BTNL2 A allele variant occurs with a high frequency in Danish patients with sarcoidosis and the AA genotype is associated with a ~threefold higher risk of sarcoidosis than the GG genotype."

This case-control study directly supports BTNL2 variation as a sarcoidosis susceptibility factor.

PMID:15735647 SUPPORT Human Clinical

Defines the molecular consequence - the A risk allele creates a cryptic splice site producing a truncated BTNL2 protein lacking the membrane anchor, reducing T-cell co-inhibitory signalling.

ANXA11 Variants (Susceptibility)

Gene: ANXA11 hgnc:535

Show evidence (3 references)

PMID:19165924 SUPPORT Human Clinical

"The strongest association signal maps to the ANXA11 (annexin A11) gene on chromosome 10q22.3."

Original GWAS implicating ANXA11 as a sarcoidosis susceptibility locus.

PMID:32552203 SUPPORT Human Clinical

"It also confirms previously reported 'protective' association between sarcoidosis and functional variant ANXA11 rs1049550*A."

Independent replication in a Greek cohort confirms the protective association of the ANXA11 rs1049550 A allele, reinforcing the locus.

PMID:29416296 SUPPORT Human Clinical

"SNPs rs1040461 and rs61860052, in ras-related protein RAS23 (RAB23) and annexin A11 (ANXA11) genes, respectively, were associated with sarcoidosis-associated uveitis."

Subgroup analysis links ANXA11 variation specifically to the uveitis phenotype, providing a genotype-phenotype edge from genetic susceptibility to ocular manifestation.

NOTCH4 Variants (Susceptibility)

Gene: NOTCH4 hgnc:7884

Show evidence (1 reference)

PMID:22952805 SUPPORT Human Clinical

"We identified a novel sarcoidosis-associated locus, NOTCH4, that reached genome-wide significance in the combined AA samples (rs715299, P(AA-meta) = 6.51 × 10(-10)) and demonstrated the independence of this locus from others in the MHC region in the same sample."

GWAS in African Americans identifies NOTCH4 as a genome-wide significant sarcoidosis susceptibility locus independent of other MHC loci.

IL27RA Variants (Susceptibility)

Gene: IL27RA hgnc:17290

Show evidence (1 reference)

PMID:31273209 PARTIAL Human Clinical

"Genetic factors affect not only the risk of developing sarcoidosis but also the disease course, which is highly variable and difficult to predict."

Nature Reviews Disease Primers review supports a polygenic contribution to sarcoidosis susceptibility including cytokine receptor variants; IL27RA is one of the implicated loci.

TSC2 / mTORC1 Pathway (Mechanistic)

Gene: TSC2 hgnc:12363

Show evidence (1 reference)

PMID:28092373 SUPPORT Model Organism

"TSC2-deficient macrophages formed mTORC1-dependent granulomatous structures in vitro and showed constitutive proliferation that was mediated by the neo-expression of cyclin-dependent kinase 4 (CDK4)."

Defines the molecular mechanism by which TSC2 loss in macrophages activates mTORC1 and induces CDK4-driven granulomatous proliferation, the macrophage-intrinsic engine of sarcoid granuloma maintenance.

💊

Medical Actions

Corticosteroid Therapy

Action: corticosteroid agent therapy MAXO:0000640

First-line treatment for symptomatic sarcoidosis. Prednisone typically initiated at 20-40mg daily with gradual taper over months. Effective for most organ manifestations.

Show evidence (2 references)

PMID:31485575 SUPPORT Human Clinical

"Glucocorticoids are the cornerstone of treatment of sarcoidosis even though evidence from randomized controlled studies is lacking."

This Mayo Clinic review establishes glucocorticoids as the cornerstone of sarcoidosis treatment.

PMID:38227868 SUPPORT Human Clinical

"Corticosteroids are the initial treatment for active disease, with refractory cases often requiring immunosuppressive or biologic therapies."

This 2024 review confirms corticosteroids as first-line initial treatment for active sarcoidosis.

Methotrexate

Action: immunosuppressive therapy Ontology label: immune suppressant agent therapy MAXO:0000297

Agent: methotrexate CHEBI:44185

Most commonly used steroid-sparing agent for chronic sarcoidosis. Allows reduction of corticosteroid dose while maintaining disease control. The PREDMETH trial (NEJM 2025) demonstrated noninferiority of methotrexate to prednisone for 24-week change in % predicted FVC, supporting methotrexate as a first-line option in selected patients.

Mechanism Target:

INHIBITS Th17.1 Polarization and IFN-gamma Production — Methotrexate suppresses pathogenic Th17/Th17.1 effector responses central to granuloma maintenance.

Show evidence (2 references)

PMID:41095908 SUPPORT Human Clinical

"Antimetabolites such as methotrexate, azathioprine, mycophenolate mofetil, and leflunomide are commonly used second-line therapies."

This evidence-based review directly supports methotrexate as a standard second-line steroid-sparing therapy in pulmonary sarcoidosis.

PMID:40387020 SUPPORT Human Clinical

"Methotrexate was noninferior to prednisone with regard to the primary end point, with an adjusted between-group difference of -1.17 percentage points (95% CI, -4.27 to 1.93)."

The PREDMETH NEJM 2025 noninferiority trial demonstrates methotrexate is noninferior to prednisone for FVC change in pulmonary sarcoidosis, supporting methotrexate as a viable first-line alternative.

Anti-TNF Therapy

Action: biologic therapy Ontology label: Immunotherapy NCIT:C15262

Anti-TNF agents, particularly infliximab, are used for refractory sarcoidosis when corticosteroids and steroid-sparing agents are insufficient.

Show evidence (1 reference)

PMID:41095908 SUPPORT Human Clinical

"For refractory disease, particularly in those with metabolically active lesions on FDG-PET, anti-tumor necrosis factor (TNF) agents like infliximab may be effective but carry risks of serious adverse effects."

This evidence-based review directly supports anti-TNF therapy, especially infliximab, as an option for refractory sarcoidosis.

JAK Inhibitor Therapy

Action: Pharmacotherapy NCIT:C15986

Janus kinase inhibitors (tofacitinib, ruxolitinib) are emerging steroid-sparing options that target IFN-gamma/JAK-STAT signalling downstream of Th17.1 cells. Pilot studies in corticosteroid-dependent and cutaneous sarcoidosis report benefit; larger trials are ongoing.

Mechanism Target:

INHIBITS Th17.1 Polarization and IFN-gamma Production — JAK inhibitors block IFN-gamma/JAK-STAT signalling, attenuating the Th17.1-driven IFN-gamma feedback that sustains granulomatous inflammation.

Show evidence (1 reference)

PMID:33825964 SUPPORT Human Clinical

"In this proof-of-concept study, the addition of a JAK-inhibitor allowed 60% of patients with pulmonary sarcoidosis to successfully taper corticosteroids."

Open-label proof-of-concept trial (NCT03793439) demonstrates tofacitinib enables steroid tapering in corticosteroid-dependent pulmonary sarcoidosis, supporting JAK inhibitors as a steroid-sparing option.

mTOR Inhibitor Therapy (Investigational)

Action: Pharmacotherapy NCIT:C15986

Inhibition of mTORC1 with rapamycin/everolimus completely resolved granulomas in Tsc2-deficient mouse models and successful single-patient use of rapamycin has been reported. Currently investigational in human sarcoidosis but mechanistically targeted at the macrophage-intrinsic granuloma maintenance arm.

Mechanism Target:

INHIBITS Macrophage Activation and mTORC1 Hyperactivation — Rapamycin/everolimus directly inhibit the mTORC1 signalling that drives macrophage proliferation and granuloma maintenance.

Show evidence (1 reference)

PMID:28092373 SUPPORT Model Organism

"Inhibition of mTORC1 induced apoptosis and completely resolved granulomas in myeloid TSC2-deficient mice."

Pharmacologic mTORC1 inhibition resolves granulomas in a sarcoid-like animal model, providing the rationale for mTOR-targeted human therapy.

🌍

Environmental Factors

Occupational Exposures

Associations have been reported with silica, other inorganic dusts, metals, and related occupational dust exposures.

Show evidence (1 reference)

PMID:35156713 SUPPORT Human Clinical

"Occupational exposures for which associations are strongest and most consistent are silica and other inorganic dusts, World Trade Center (WTC) dust, and metals."

This occupational case series review directly supports industrial dust and metal exposure as relevant environmental associations in sarcoidosis.

Infectious Triggers

Mycobacterial and propionibacterial antigens have been implicated as potential triggers

Show evidence (1 reference)

PMID:22596102 SUPPORT Human Clinical

"Mycobacterial and propionibacterial organisms are the most commonly implicated potential etiologic agents."

This pathology study directly supports mycobacterial and propionibacterial organisms as leading infectious candidates in sarcoidosis pathogenesis.

🔬

Biochemical Markers

Elevated ACE (Elevated)

Context: Serum angiotensin-converting enzyme often elevated but not specific for diagnosis

Show evidence (1 reference)

PMID:36778180 SUPPORT Human Clinical

"Raised angiotensin-converting enzyme (ACE) levels were found in 56.8% of patients."

This retrospective cohort directly supports frequent elevation of serum ACE in sarcoidosis while remaining compatible with its limited diagnostic specificity.

Hypercalcemia (Elevated)

Context: Due to ectopic 1,25-dihydroxyvitamin D (calcitriol) production by granuloma macrophages

Show evidence (1 reference)

PMID:24663253 SUPPORT Human Clinical

This case-based report explicitly supports hypercalcemia in sarcoidosis and ties it to macrophage-driven calcitriol dysregulation within granulomatous tissue.

Elevated Inflammatory Markers (Elevated)

Context: ESR and CRP may be elevated during active disease

Show evidence (1 reference)

PMID:32407763 PARTIAL Human Clinical

"In contrast, ESR and Hs-CRP emerges to be more sensitive markers of active CS."

This study directly supports ESR and CRP elevation in active cardiac sarcoidosis, partially supporting their broader use as inflammatory activity markers in sarcoidosis.

{ }

Source YAML

click to show

name: Sarcoidosis
creation_date: '2026-01-13T07:11:10Z'
updated_date: '2026-04-30T12:00:00Z'
category: Immune
description: >
  Sarcoidosis is a multisystem inflammatory disease of unknown etiology characterized
  by the formation of non-caseating granulomas, most commonly affecting the lungs
  and lymph nodes. The leading model holds that genetically susceptible individuals
  (HLA-DRB1, BTNL2, ANXA11, NOTCH4, IL27RA risk alleles) mount an exaggerated
  CD4+ T-cell response to a poorly degradable antigen (mycobacterial KatG/ESAT-6,
  propionibacterial, or environmental dusts), driving Th1/Th17.1-skewed inflammation,
  IFN-gamma production, and macrophage transformation into epithelioid and
  multinucleated giant cells organized into granulomas. Macrophage-intrinsic
  mTORC1 hyperactivation sustains granuloma maintenance and correlates with
  progressive disease. The disease predominantly affects adults aged 20-40 years,
  with higher incidence in African Americans and Northern Europeans. Clinical
  presentation ranges from asymptomatic to severe organ dysfunction; while many
  cases resolve spontaneously, chronic progressive disease (10-30%) progresses to
  pulmonary fibrosis, cardiac, neurologic, ocular, or cutaneous involvement.
disease_term:
  preferred_term: sarcoidosis
  term:
    id: MONDO:0019338
    label: sarcoidosis
parents:
- Granulomatous Disease
- Immune-Mediated Disease
prevalence:
- population: Europe (Germany)
  percentage: 44-48 per 100,000
  evidence:
  - reference: PMID:27454307
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In Germany, the incidence is estimated to be 10 per 100,000, and the prevalence 44-48 per 100,000."
    explanation: German epidemiologic data supporting European prevalence estimate.
  - reference: ORPHA:797
    supports: SUPPORT
    snippet: "A rare multisystemic, autoinflammatory disorder of unknown etiology characterized by the formation of immune, non-caseating granulomas in any organ(s), leading to variable clinical symptoms and severity."
    explanation: Orphanet classifies sarcoidosis as a rare multisystemic autoinflammatory disorder.
inheritance:
- name: Polygenic susceptibility
  description: Sarcoidosis is not a Mendelian disorder but shows familial clustering with polygenic susceptibility (HLA-DRB1, BTNL2, ANXA11). Risk is increased in first-degree relatives.
  evidence:
  - reference: PMID:27454307
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Familial clusters can occur."
    explanation: Familial clustering supports genetic predisposition without Mendelian inheritance.
has_subtypes:
- name: Pulmonary Sarcoidosis
  description: Most common form, affecting lungs and hilar lymph nodes; staged by chest radiograph findings.
- name: Cardiac Sarcoidosis
  description: Myocardial granulomas causing conduction abnormalities, heart failure, or sudden death.
- name: Neurosarcoidosis
  description: CNS involvement causing cranial neuropathies, meningitis, or mass lesions.
- name: Cutaneous Sarcoidosis
  description: Skin manifestations including erythema nodosum, lupus pernio, and papular lesions.
mechanistic_hypotheses:
- hypothesis_group_id: antigen_persistence_granuloma_chronicity_model
  hypothesis_label: Antigen Persistence / Th17.1 / mTORC1 Granuloma Chronicity Model
  status: EMERGING
  applies_to_subtypes:
  - Pulmonary Sarcoidosis
  description: >-
    Sarcoidosis is modeled as a genetically conditioned, antigen-driven
    granulomatous immune response in which poorly degradable or repeatedly
    encountered antigens are presented by macrophage-lineage antigen-presenting
    cells to CD4+ T cells. The activated T-cell compartment polarizes toward
    IFN-gamma-producing Th17.1/Th1-like effector states while regulatory T-cell
    restraint is insufficient. This cytokine circuit recruits and activates
    macrophages, promotes epithelioid and multinucleated giant-cell granuloma
    architecture, and intersects with macrophage-intrinsic metabolic programs
    such as mTORC1 activation. Resolution is hypothesized to require antigen
    clearance or sequestration plus restoration of regulatory and apoptotic
    checkpoints; chronic disease and fibrosis occur when antigen persistence,
    Th17.1 feedback, macrophage survival/proliferation, and tissue-repair
    programs remain engaged.
  notes: >-
    Retained as EMERGING after the 2026 OpenScientist hypothesis-search report
    (kb/hypotheses/Sarcoidosis/antigen_persistence_granuloma_chronicity_model/openscientist.md).
    The report judged the model partially supported: antigen-driven CD4 T-cell
    responses, Th17.1/Treg imbalance, and macrophage mTORC1 granuloma biology
    are individually well supported, but the integrated Th17.1-to-macrophage
    mTORC1 link remains unproven and fibrosis may diverge through distinct
    profibrotic/EMT-like tissue-remodeling programs. Best current fit is
    non-Lofgren, chronic/progressive pulmonary sarcoidosis rather than all
    sarcoidosis phenotypes.
  evidence:
  - reference: PMID:38165044
    reference_title: "Immune mechanisms of granuloma formation in sarcoidosis and tuberculosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Sarcoidosis is a complex immune-mediated disease characterized by clusters of immune cells called granulomas."
    explanation: >
      Recent mechanistic review used as the seed reference for the
      hypothesis-search deep-research run and for the antigen/T-cell/macrophage
      granuloma-chronicity framing.
  - reference: PMID:31273209
    reference_title: "Sarcoidosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The disease develops in genetically predisposed individuals with exposure to an as-yet unknown antigen."
    explanation: >
      Nature Reviews Disease Primers review supports the central upstream
      premise of this hypothesis: genetically predisposed patients encounter an
      unknown antigenic trigger.
pathophysiology:
- name: Genetic Susceptibility
  description: >
    Sarcoidosis is a polygenic immune disorder. Risk-associated variants in HLA
    class II (DRB1 lineages), the truncating splice variant rs2076530 in BTNL2
    (a T-cell co-inhibitory butyrophilin-like immunoglobulin superfamily member),
    the missense ANXA11 R230C (rs1049550), NOTCH4, and IL27RA collectively shift
    antigen presentation, T-cell co-stimulation/inhibition, and macrophage
    apoptosis thresholds, predisposing to exaggerated granulomatous response on
    antigen encounter.
  evidence:
  - reference: PMID:15735647
    reference_title: "Sarcoidosis is associated with a truncating splice site mutation in BTNL2."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The G --> A transition constituting rs2076530 leads to the use of a cryptic splice site located 4 bp upstream of the affected wild-type donor site. Transcripts of the risk-associated allele have a premature stop in the spliced mRNA. The resulting protein lacks the C-terminal IgC domain and transmembrane helix, thereby disrupting the membrane localization of the protein"
    explanation: This case-control SNP scan identifies the truncating BTNL2 splice variant rs2076530 as a sarcoidosis risk factor independent of HLA-DRB1, with a defined molecular consequence (loss of membrane-anchored co-inhibitory protein).
  - reference: PMID:19165924
    reference_title: "Genome-wide association study identifies ANXA11 as a new susceptibility locus for sarcoidosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The strongest association signal maps to the ANXA11 (annexin A11) gene on chromosome 10q22.3."
    explanation: GWAS plus replication establishes ANXA11 as a major sarcoidosis susceptibility locus; the lead missense R230C (rs1049550) variant defined in this work is the molecular entry point for the apoptosis/proliferation arm of the pathograph.
  - reference: PMID:19165924
    reference_title: "Genome-wide association study identifies ANXA11 as a new susceptibility locus for sarcoidosis."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Annexin A11 has complex and essential functions in several biological pathways, including apoptosis and proliferation."
    explanation: Functional context for why ANXA11 risk variants are mechanistically relevant - the gene regulates apoptosis and proliferation, which are precisely the macrophage processes dysregulated in granuloma maintenance.
  cell_types:
  - preferred_term: CD4-positive helper T cell
    term:
      id: CL:0000492
      label: CD4-positive helper T cell
  biological_processes:
  - preferred_term: antigen processing and presentation
    term:
      id: GO:0019882
      label: antigen processing and presentation
  downstream:
  - target: Antigen Recognition and CD4+ T-Cell Activation
    description: Risk alleles in HLA-DRB1 and BTNL2 alter MHC class II antigen presentation and T-cell co-inhibition, lowering the threshold for an exaggerated CD4+ T-cell response to a triggering antigen.
    causal_link_type: DIRECT
    hypothesis_groups:
    - antigen_persistence_granuloma_chronicity_model
- name: Antigen Recognition and CD4+ T-Cell Activation
  description: >
    Susceptibility alleles allow MHC class II presentation of poorly degradable
    antigens (mycobacterial KatG, ESAT-6, Ag85A, sodA, HSP; propionibacterial
    proteins; or environmental particulates) to CD4+ T cells, which expand
    clonally and acquire a Th1/Th17.1 effector program with high IFN-gamma
    production.
  evidence:
  - reference: PMID:21092305
    reference_title: "Multiple mycobacterial antigens are targets of the adaptive immune response in pulmonary sarcoidosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Alveolar T-cells from twenty-two of the 31 sarcoidosis patients produced a CD4+ response to at least one of ESAT-6, katG, Ag85A, sodA, or HSP, compared to two of 14 PPD- controls (p = 0.0008)"
    explanation: Direct demonstration that lung-resident T cells from sarcoidosis patients recognize mycobacterial antigens, supporting an antigen-driven step linking the susceptibility node to T-cell activation.
  - reference: PMID:31273209
    reference_title: "Sarcoidosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The typical T cell accumulation, local T cell immune response and granuloma formation in the lungs indicate that the inflammatory response in sarcoidosis is induced by specific antigens, possibly including self-antigens, which is consistent with an autoimmune involvement."
    explanation: >
      Review-level synthesis supports antigen-driven local T-cell responses in
      pulmonary sarcoidosis while preserving uncertainty about antigen identity.
  cell_types:
  - preferred_term: CD4-positive helper T cell
    term:
      id: CL:0000492
      label: CD4-positive helper T cell
  - preferred_term: alveolar macrophage
    term:
      id: CL:0000583
      label: alveolar macrophage
  biological_processes:
  - preferred_term: antigen processing and presentation of peptide antigen via MHC class II
    term:
      id: GO:0002495
      label: antigen processing and presentation of peptide antigen via MHC class II
  - preferred_term: T cell activation
    term:
      id: GO:0042110
      label: T cell activation
  downstream:
  - target: Th17.1 Polarization and IFN-gamma Production
    description: Antigen-activated CD4+ T cells in lung tissue polarize toward an IFN-gamma-producing Th17.1 phenotype that drives sustained granulomatous inflammation.
    causal_link_type: DIRECT
    hypothesis_groups:
    - antigen_persistence_granuloma_chronicity_model
- name: Th17.1 Polarization and IFN-gamma Production
  description: >
    Plasticity within the Th17 lineage produces IFN-gamma-producing Th17.1 cells
    that are the dominant source of IFN-gamma in pulmonary sarcoidosis and
    correlate with progressive (non-Lofgren) disease. Concurrent Treg dysfunction
    (impaired survival, altered CTLA-4 expression) removes the brake on this
    effector response.
  evidence:
  - reference: PMID:27379969
    reference_title: "T-cell immunology in sarcoidosis: Disruption of a delicate balance between helper and regulatory T-cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "it was demonstrated that Th17.1-cells rather than Th1-cells are responsible for the exaggerated IFN-γ production in pulmonary sarcoidosis."
    explanation: Reviews the paradigm shift identifying Th17.1 cells (not classical Th1) as the dominant IFN-gamma source in sarcoidosis, anchoring this node mechanistically.
  - reference: PMID:29310925
    reference_title: "Th17-lineage cells in pulmonary sarcoidosis and Lofgren's syndrome: Friend or foe?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In non-LS sarcoidosis patients, IFN-γ-producing Th17.1-cells appear to be more pathogenic and possibly linked to disease progression"
    explanation: Direct support that Th17.1 polarization marks the pathogenic, progression-prone arm of sarcoidosis and is the upstream effector that drives macrophage transformation.
  - reference: PMID:24882950
    reference_title: "Bronchoalveolar lavage fluid IFN-gamma+ Th17 cells and regulatory T cells in pulmonary sarcoidosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The proportion of Th17 cells positive for IFN-gamma was greater in sarcoidosis than controls (median 72.4% versus 31%, P = 0.0005) and increased with radiologic stage (N = 23, rho = 0.45, and P = 0.03)."
    explanation: Quantitative evidence that the IFN-gamma+ Th17 (Th17.1) compartment is enriched in lung lavage of sarcoidosis patients and tracks with radiographic stage.
  - reference: PMID:26376720
    reference_title: "Impaired survival of regulatory T cells in pulmonary sarcoidosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In untreated patients with active pulmonary sarcoidosis, Tregs show impaired survival and enhanced apoptotic susceptibility towards CD95L. Increased apoptosis likely contributes to the insufficient immunosuppressive function of sarcoidosis Tregs."
    explanation: Treg apoptotic susceptibility removes the suppressive brake on Th17.1 effector cells, helping maintain chronic granulomatous inflammation.
  cell_types:
  - preferred_term: T-helper 17 cell
    term:
      id: CL:0000899
      label: T-helper 17 cell
  - preferred_term: regulatory T cell
    term:
      id: CL:0000815
      label: regulatory T cell
  biological_processes:
  - preferred_term: T-helper 17 type immune response
    term:
      id: GO:0072538
      label: T-helper 17 type immune response
  - preferred_term: regulatory T cell apoptotic process
    term:
      id: GO:1902482
      label: regulatory T cell apoptotic process
  downstream:
  - target: Macrophage Activation and mTORC1 Hyperactivation
    description: IFN-gamma-rich Th17.1 inflammation, persistent antigen, and other tissue signals are hypothesized to converge on recruitment, activation, and metabolic reprogramming of macrophages; direct Th17.1-to-macrophage mTORC1 causality in human sarcoidosis remains unproven.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Unresolved coupling between Th17.1 cytokines, persistent antigen, macrophage growth/survival signals, and macrophage mTORC1 activation.
    hypothesis_groups:
    - antigen_persistence_granuloma_chronicity_model
- name: Macrophage Activation and mTORC1 Hyperactivation
  description: >
    Chronic antigenic stimulation drives macrophage hypertrophy, proliferation,
    and transformation into epithelioid cells. A macrophage-intrinsic increase
    in mTORC1 signaling (genetically modeled by Tsc2 deletion) is sufficient to
    initiate and sustain non-caseating granulomas, via CDK4-dependent proliferation,
    glycolytic reprogramming, and suppression of macrophage apoptosis. mTORC1
    activation is enriched in progressive human sarcoidosis lesions.
  evidence:
  - reference: PMID:28092373
    reference_title: "Chronic signaling via the metabolic checkpoint kinase mTORC1 induces macrophage granuloma formation and marks sarcoidosis progression."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "We found that activation of the metabolic checkpoint kinase mTORC1 in macrophages by deletion of the gene encoding tuberous sclerosis 2 (Tsc2) was sufficient to induce hypertrophy and proliferation, resulting in excessive granuloma formation in vivo."
    explanation: Conditional Tsc2 deletion in mouse myeloid cells is sufficient to recapitulate sarcoid-like granulomas, mechanistically anchoring macrophage-intrinsic mTORC1 hyperactivation as a granuloma-initiating step.
  - reference: PMID:28092373
    reference_title: "Chronic signaling via the metabolic checkpoint kinase mTORC1 induces macrophage granuloma formation and marks sarcoidosis progression."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In human sarcoidosis patients, mTORC1 activation, macrophage proliferation and glycolysis were identified as hallmarks that correlated with clinical disease progression."
    explanation: Re-analysis of human sarcoidosis biopsies translates the mouse mechanism - mTORC1 activity, macrophage proliferation, and glycolysis distinguish progressive from self-limiting disease in patients.
  - reference: PMID:29104468
    reference_title: "Extensively disturbance of regulatory T cells - Th17 cells balance in stage II pulmonary sarcoidosis."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Disturbance of T memory cells, Th1/Th2, and Tregs/Th17 cells, and activation of PI3K/Akt signaling were seen in newly diagnosed stage II pulmonary sarcoidosis"
    explanation: Independent confirmation that PI3K/Akt (upstream of mTORC1) is activated in pulmonary sarcoidosis BAL cells, supporting parallel relevance of this metabolic axis in human disease.
  cell_types:
  - preferred_term: epithelioid macrophage
    term:
      id: CL:0002150
      label: epithelioid macrophage
  - preferred_term: macrophage
    term:
      id: CL:0000235
      label: macrophage
  biological_processes:
  - preferred_term: TORC1 signaling
    term:
      id: GO:0038202
      label: TORC1 signaling
    modifier: INCREASED
  - preferred_term: macrophage activation
    term:
      id: GO:0042116
      label: macrophage activation
  - preferred_term: glycolytic process
    term:
      id: GO:0006096
      label: glycolytic process
    modifier: INCREASED
  - preferred_term: negative regulation of macrophage apoptotic process
    term:
      id: GO:2000110
      label: negative regulation of macrophage apoptotic process
  downstream:
  - target: Granuloma Formation
    description: mTORC1-driven hypertrophic, proliferating macrophages aggregate with multinucleated giant cells and CD4+ T cells to form non-caseating granulomas.
    causal_link_type: DIRECT
    hypothesis_groups:
    - antigen_persistence_granuloma_chronicity_model
- name: Granuloma Formation
  description: >
    Non-caseating granulomas consist of organized collections of activated
    macrophages (epithelioid cells), multinucleated giant cells, and CD4+ T cells.
    Th1/Th17.1 immune responses drive granuloma development in response to
    persistent antigens. Granulomas are the defining histopathologic lesion that
    mediates the downstream organ-level phenotypes of sarcoidosis.
  evidence:
  - reference: PMID:35011621
    reference_title: "Clinical Features, Histopathology and Differential Diagnosis of Sarcoidosis."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Sarcoidosis is a chameleon disease of unknown etiology, characterized by the growth of non-necrotizing and non-caseating granulomas"
    explanation: "This review confirms the characteristic non-caseating granuloma formation in sarcoidosis."
  - reference: PMID:38165044
    reference_title: "Immune mechanisms of granuloma formation in sarcoidosis and tuberculosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Sarcoidosis is a complex immune-mediated disease characterized by clusters of immune cells called granulomas."
    explanation: This 2024 JCI mechanistic review frames sarcoidosis as a granuloma-defined immune-mediated disease and is the source for the integrated antigen-T-cell-macrophage causal chain summarized here.
  - reference: PMID:33329511
    reference_title: "Treatment of Sarcoidosis: A Multidisciplinary Approach."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The sarcoidosis granuloma is formed by a distinct conglomeration of multinucleated giant cells and epithelioid macrophages surrounded by a rim of CD4+ T cells"
    explanation: >
      Full-text review-level support for the core immune-cell architecture of
      sarcoid granulomas: macrophage-lineage giant/epithelioid cells surrounded
      by CD4+ T cells.
  cell_types:
  - preferred_term: epithelioid macrophage
    term:
      id: CL:0002150
      label: epithelioid macrophage
  - preferred_term: multinucleated giant cell
    term:
      id: CL:0000647
      label: multinucleated giant cell
  - preferred_term: CD4-positive helper T cell
    term:
      id: CL:0000492
      label: CD4-positive helper T cell
  biological_processes:
  - preferred_term: granuloma formation
    term:
      id: GO:0002432
      label: granuloma formation
  downstream:
  - target: Macrophage Calcitriol Production
    description: Granuloma macrophages express CYP27B1 and convert 25-hydroxyvitamin D to active 1,25-dihydroxyvitamin D outside normal renal regulation, predisposing to hypercalcemia.
    causal_link_type: DIRECT
  - target: Macrophage ACE Production
    description: Epithelioid macrophages within granulomas synthesize angiotensin-converting enzyme, producing the elevated serum ACE characteristic of active sarcoidosis.
    causal_link_type: DIRECT
  - target: Fibrotic Tissue Remodeling
    description: Persistent granulomatous inflammation is associated with later TGF-beta-driven myofibroblast programs and excessive ECM deposition in a subset of patients, but the switch from active granulomas to fibrotic remodeling is not resolved and may involve partly distinct profibrotic pathways.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Unresolved granuloma-to-fibrosis switch involving TGF-beta signaling, epithelial-mesenchymal transition-like programs, fibroblast activation, and chronic tissue injury.
    hypothesis_groups:
    - antigen_persistence_granuloma_chronicity_model
- name: Macrophage Calcitriol Production
  description: >
    Activated monocytes and macrophages within sarcoid granulomas express
    1-alpha-hydroxylase (CYP27B1), converting 25-hydroxyvitamin D to
    1,25-dihydroxyvitamin D outside normal PTH/FGF23 regulation. This extrarenal
    calcitriol synthesis, with optional PTHrP secretion, drives intestinal calcium
    absorption and bone resorption, producing hypercalcemia and hypercalciuria.
  evidence:
  - reference: PMID:24663253
    reference_title: "Serum vitamin D levels may not reflect tissue-level vitamin D in sarcoidosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hypercalcemia in sarcoidosis is due to three mechanistic reasons: (1) systemic conversion of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D by the enzyme 1-alpha hydroxylase produced by activated monocyte/macrophage system, (2) production of parathormone-related peptide (PTHrP) by the sarcoid granuloma, (3) tissue-level conversion of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D by 1-alphahydroxylase produced by local monocyte/macrophage system in the sarcoid granuloma."
    explanation: Mechanistic case-based report explicitly attributing sarcoid hypercalcemia to macrophage-driven extrarenal CYP27B1 expression and PTHrP, defining the molecular bridge from granuloma to the hypercalcemia phenotype.
  - reference: PMID:23337133
    reference_title: "Hypercalcemia associated with mineral oil-induced sclerosing paraffinomas."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hypercalcemia associated with mineral oil induced skin lesions is likely driven by unregulated expression of CYP27b1 by inflammatory monocytes and macrophages infiltrating the dermis."
    explanation: A non-sarcoidosis granulomatous condition independently demonstrates that ectopic CYP27B1 expression in tissue macrophages causes hypercalcemia, generalizing the macrophage-calcitriol mechanism.
  cell_types:
  - preferred_term: macrophage
    term:
      id: CL:0000235
      label: macrophage
  biological_processes:
  - preferred_term: vitamin D metabolic process
    term:
      id: GO:0042359
      label: vitamin D metabolic process
    modifier: INCREASED
  downstream:
  - target: Hypercalcemia
    description: Extrarenal 1,25-dihydroxyvitamin D production by granuloma macrophages causes hypercalcemia in approximately 5-10% of patients.
    causal_link_type: DIRECT
- name: Macrophage ACE Production
  description: >
    Epithelioid macrophages within granulomas constitutively express
    angiotensin-converting enzyme (ACE), and serum ACE elevation reflects total
    granuloma burden. Single-cell RNA-seq of cutaneous sarcoid granulomas has
    identified TREM2-positive ACE-expressing macrophages as a granuloma-resident
    population, supporting macrophage origin of the serum biomarker.
  evidence:
  - reference: PMID:38038136
    reference_title: "Activation of the pentose phosphate pathway in macrophages is crucial for granuloma formation in sarcoidosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the percentages of triggering receptor expressed on myeloid cells 2-positive (TREM2-positive) macrophages expressing angiotensin-converting enzyme (ACE) and lysozyme, diagnostic makers of sarcoidosis, were increased in cutaneous sarcoidosis granulomas."
    explanation: Single-cell RNA-seq demonstrates TREM2+ macrophages expressing ACE are enriched in sarcoid granulomas, directly supporting the macrophage origin of serum ACE elevation.
  cell_types:
  - preferred_term: epithelioid macrophage
    term:
      id: CL:0002150
      label: epithelioid macrophage
  downstream:
  - target: Elevated ACE
    description: Granuloma-resident epithelioid macrophages secrete ACE; circulating levels are raised in active sarcoidosis and broadly correlate with granuloma burden.
    causal_link_type: DIRECT
- name: Fibrotic Tissue Remodeling
  description: >
    In approximately 10-30% of patients with chronic disease, persistent
    granulomatous inflammation transitions to a profibrotic state characterized
    by TGF-beta signaling, fibroblast/myofibroblast activation, and excessive
    extracellular matrix deposition. The end result is irreversible parenchymal
    fibrosis with restrictive physiology, fibrocystic remodeling, and respiratory
    failure. This node conforms to the conserved fibrotic response module.
  conforms_to: "fibrotic_response#Mesenchymal Cell Activation"
  evidence:
  - reference: PMID:41095908
    reference_title: "Immunosuppressive Therapies in Pulmonary Sarcoidosis: A Practical, Evidence-Based Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Although many patients experience spontaneous remission, approximately 10-30% develop progressive pulmonary disease, which may lead to fibrocystic changes, respiratory failure, and death."
    explanation: This review directly supports progression from pulmonary sarcoidosis to fibrocystic and fibrotic lung disease in a substantial subset of patients.
  cell_types:
  - preferred_term: fibroblast
    term:
      id: CL:0000057
      label: fibroblast
  biological_processes:
  - preferred_term: extracellular matrix organization
    term:
      id: GO:0030198
      label: extracellular matrix organization
    modifier: INCREASED
  downstream:
  - target: Pulmonary Fibrosis
    description: Persistent granulomatous inflammation drives ECM deposition, restrictive physiology, and irreversible fibrocystic remodeling in 10-30% of patients.
    causal_link_type: DIRECT
phenotypes:
- name: Mediastinal Lymphadenopathy
  category: Pulmonary
  frequency: VERY_FREQUENT
  description: Symmetric enlargement of hilar and mediastinal lymph nodes, often the presenting finding on chest radiograph.
  phenotype_term:
    preferred_term: Mediastinal lymphadenopathy
    term:
      id: HP:0100721
      label: Mediastinal lymphadenopathy
  evidence:
  - reference: PMID:31485575
    reference_title: "Clinical Manifestations, Diagnosis, and Treatment of Sarcoidosis."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Although intrathoracic involvement is the hallmark of the disease, present in over 90% of patients, sarcoidosis can affect virtually any organ."
    explanation: This Mayo Clinic review strongly supports intrathoracic involvement as the dominant manifestation of sarcoidosis, but only indirectly supports mediastinal lymphadenopathy specifically.
- name: Dyspnea
  category: Pulmonary
  frequency: FREQUENT
  description: Shortness of breath due to pulmonary involvement and reduced lung function.
  phenotype_term:
    preferred_term: Dyspnea
    term:
      id: HP:0002094
      label: Dyspnea
  evidence:
  - reference: PMID:38227868
    reference_title: "Sarcoidosis: Evaluation and Treatment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Ongoing dyspnea and dry cough in a young to middle-aged adult should increase the suspicion for sarcoidosis."
    explanation: This 2024 American Family Physician review identifies dyspnea as a key presenting symptom that should raise suspicion for sarcoidosis.
- name: Nonproductive Cough
  category: Pulmonary
  frequency: FREQUENT
  description: Dry, non-productive cough from airway and parenchymal inflammation.
  phenotype_term:
    preferred_term: Nonproductive cough
    term:
      id: HP:0031246
      label: Nonproductive cough
  evidence:
  - reference: PMID:38227868
    reference_title: "Sarcoidosis: Evaluation and Treatment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Ongoing dyspnea and dry cough in a young to middle-aged adult should increase the suspicion for sarcoidosis."
    explanation: Dry cough is identified as a hallmark symptom that should raise clinical suspicion for sarcoidosis in younger adults.
- name: Fatigue
  category: Constitutional
  frequency: FREQUENT
  description: Chronic fatigue is one of the most debilitating symptoms, often persisting after disease resolution.
  phenotype_term:
    preferred_term: Fatigue
    term:
      id: HP:0012378
      label: Fatigue
  evidence:
  - reference: PMID:38227868
    reference_title: "Sarcoidosis: Evaluation and Treatment."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients with sarcoidosis can exhibit constitutional symptoms such as fever, unintentional weight loss, and fatigue."
    explanation: This review supports fatigue as a recognized constitutional symptom in sarcoidosis, but the wording is not strong enough on its own to justify a VERY_FREQUENT frequency assignment.
- name: Erythema Nodosum
  category: Dermatologic
  frequency: OCCASIONAL
  description: Painful red nodules on the shins, often associated with acute sarcoidosis (Lofgren syndrome).
  phenotype_term:
    preferred_term: Erythema nodosum
    term:
      id: HP:0012219
      label: Erythema nodosum
  evidence:
  - reference: PMID:39082153
    reference_title: "Löfgren syndrome, characteristics of Japanese cases: A case and a review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Löfgren syndrome (LS) is a sarcoidosis subtype characterised by an acute disease course, bilateral hilar lymphadenopathy (BHL), erythema nodosum (EN), and ankle arthritis."
    explanation: This review of Lofgren syndrome directly supports erythema nodosum as a recognized acute cutaneous manifestation of sarcoidosis.
- name: Uveitis
  category: Ophthalmologic
  frequency: OCCASIONAL
  description: Eye inflammation that can lead to vision impairment if untreated. May be anterior, posterior, or panuveitis.
  phenotype_term:
    preferred_term: Uveitis
    term:
      id: HP:0000554
      label: Uveitis
  evidence:
  - reference: PMID:33173272
    reference_title: "Ocular Manifestations of Sarcoidosis in a South Florida Population."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Uveitis was the most common ocular manifestation."
    explanation: This retrospective series directly supports uveitis as a common ocular manifestation among patients with ocular sarcoidosis.
- name: Hypercalcemia
  category: Metabolic
  frequency: OCCASIONAL
  description: Elevated serum calcium driven by extrarenal 1,25-dihydroxyvitamin D synthesis by granuloma macrophages, with optional PTHrP secretion. Affects approximately 5-10% of patients and may cause nephrolithiasis or nephrocalcinosis.
  phenotype_term:
    preferred_term: Hypercalcemia
    term:
      id: HP:0003072
      label: Hypercalcemia
  evidence:
  - reference: PMID:24663253
    reference_title: "Serum vitamin D levels may not reflect tissue-level vitamin D in sarcoidosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hypercalcemia in sarcoidosis is due to three mechanistic reasons: (1) systemic conversion of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D by the enzyme 1-alpha hydroxylase produced by activated monocyte/macrophage system, (2) production of parathormone-related peptide (PTHrP) by the sarcoid granuloma, (3) tissue-level conversion of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D by 1-alphahydroxylase produced by local monocyte/macrophage system in the sarcoid granuloma."
    explanation: Directly supports hypercalcemia as a phenotype of sarcoidosis with a defined macrophage-CYP27B1 mechanism.
- name: Pulmonary Fibrosis
  category: Pulmonary
  frequency: OCCASIONAL
  description: Irreversible parenchymal fibrosis in approximately 10-30% of patients with chronic disease, producing restrictive lung physiology, fibrocystic remodeling, and respiratory failure.
  subtype: Pulmonary Sarcoidosis
  phenotype_term:
    preferred_term: Pulmonary fibrosis
    term:
      id: HP:0002206
      label: Pulmonary fibrosis
    clinical_course: PROGRESSIVE
  evidence:
  - reference: PMID:41095908
    reference_title: "Immunosuppressive Therapies in Pulmonary Sarcoidosis: A Practical, Evidence-Based Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Although many patients experience spontaneous remission, approximately 10-30% develop progressive pulmonary disease, which may lead to fibrocystic changes, respiratory failure, and death."
    explanation: Directly supports pulmonary fibrosis as a progression-related phenotype occurring in a substantial subset of sarcoidosis patients.
- name: Atrioventricular Block
  category: Cardiac
  frequency: OCCASIONAL
  description: Conduction system involvement from myocardial granulomas. AV block (often high-grade) is a common cardiac sarcoidosis presentation; QRS prolongation greater than 120 ms is a screening indicator.
  subtype: Cardiac Sarcoidosis
  phenotype_term:
    preferred_term: Atrioventricular block
    term:
      id: HP:0001678
      label: Atrioventricular block
  evidence:
  - reference: PMID:39621157
    reference_title: "Holter Monitoring and Cardiac Biomarkers in Screening for Cardiac Sarcoidosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "male gender, a QRS duration > 120 ms, and nsVT on Holter monitoring were identified as significant markers associated with the presence of cardiac sarcoidosis"
    explanation: Cohort screening study supports conduction abnormalities (QRS >120 ms, including AV block) as defining cardiac sarcoidosis features.
- name: Ventricular Arrhythmia
  category: Cardiac
  frequency: OCCASIONAL
  description: Sustained or non-sustained ventricular tachycardia arising from granulomatous scarring and re-entrant circuits in the myocardium. Major contributor to morbidity and mortality in cardiac sarcoidosis.
  subtype: Cardiac Sarcoidosis
  phenotype_term:
    preferred_term: Ventricular arrhythmia
    term:
      id: HP:0004308
      label: Ventricular arrhythmia
  evidence:
  - reference: PMID:39621157
    reference_title: "Holter Monitoring and Cardiac Biomarkers in Screening for Cardiac Sarcoidosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Early detection of cardiac sarcoidosis (CS) is crucial due to its association with severe complications such as ventricular arrhythmias, heart failure, and sudden cardiac death."
    explanation: Directly supports ventricular arrhythmia as a recognized cardiac sarcoidosis complication.
- name: Sudden Cardiac Death
  category: Cardiac
  frequency: OCCASIONAL
  description: Sudden cardiac death from granuloma-related ventricular arrhythmia or high-grade conduction block; a feared late complication of cardiac sarcoidosis.
  subtype: Cardiac Sarcoidosis
  severity: SEVERE
  phenotype_term:
    preferred_term: Sudden cardiac death
    term:
      id: HP:0001645
      label: Sudden cardiac death
  evidence:
  - reference: PMID:39621157
    reference_title: "Holter Monitoring and Cardiac Biomarkers in Screening for Cardiac Sarcoidosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Early detection of cardiac sarcoidosis (CS) is crucial due to its association with severe complications such as ventricular arrhythmias, heart failure, and sudden cardiac death."
    explanation: Directly supports sudden cardiac death as a severe sarcoidosis complication driven by myocardial granulomatous involvement.
- name: Facial Palsy
  category: Neurologic
  frequency: OCCASIONAL
  description: Cranial nerve VII palsy is one of the most common cranial neuropathies in neurosarcoidosis, sometimes bilateral and often presenting subacutely. CNS involvement occurs in 5-15% of patients.
  subtype: Neurosarcoidosis
  phenotype_term:
    preferred_term: Facial palsy
    term:
      id: HP:0010628
      label: Facial palsy
  evidence:
  - reference: PMID:33110001
    reference_title: "Neuro-Ophthalmic Manifestations of Sarcoidosis."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Sarcoidosis is an idiopathic, multisystem, inflammatory disease that has central nervous system involvement in 5%-15% of cases."
    explanation: Establishes CNS involvement frequency in sarcoidosis; cranial neuropathies including facial palsy are recognized presenting features.
- name: Lupus Pernio
  category: Dermatologic
  frequency: OCCASIONAL
  description: Chronic, indurated violaceous plaques on the nose, cheeks, ears, and digits. Strongly associated with chronic, fibrotic, and treatment-refractory sarcoidosis and upper-airway involvement.
  subtype: Cutaneous Sarcoidosis
  phenotype_term:
    preferred_term: lupus pernio
    term:
      id: HP:0200035
      label: Skin plaque
    clinical_course: PROGRESSIVE
  evidence:
  - reference: PMID:30555667
    reference_title: "Lupus pernio (Besnier-Tenneson syndrome): A rare form of sarcoidosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "LP is a rare presentation with infiltrated erythematoviolaceous plaques affecting the nose."
    explanation: This case report and literature review directly identifies lupus pernio as a cutaneous sarcoidosis manifestation characterized by infiltrated violaceous plaques.
- name: Arthralgia
  category: Musculoskeletal
  frequency: FREQUENT
  description: Joint pain affects approximately 32% of sarcoidosis patients; acute sarcoid arthritis (often ankle-predominant) occurs in ~19%, frequently as part of Lofgren syndrome with erythema nodosum and bilateral hilar lymphadenopathy.
  phenotype_term:
    preferred_term: Arthralgia
    term:
      id: HP:0002829
      label: Arthralgia
  evidence:
  - reference: PMID:38281070
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The PPE for sarcoid arthritis (SA) was 19% (95% CI 14, 24; I2 = 95%), and 32% (95% CI 13, 51; I2 = 99%) for arthralgia."
    explanation: Systematic review and meta-analysis of 49 studies (8574 patients) establishes arthralgia pooled prevalence at 32% and sarcoid arthritis at 19%.
  - reference: PMID:27454307
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Systemic symptoms include fatigue, night sweats, weight loss, fever, arthralgia and myalgia."
    explanation: Epidemiologic review listing arthralgia as a recognized systemic symptom of sarcoidosis.
- name: Fever
  category: Constitutional
  frequency: OCCASIONAL
  description: Low-grade fever occurs in a subset of patients, more common with acute sarcoidosis or Lofgren syndrome.
  phenotype_term:
    preferred_term: Fever
    term:
      id: HP:0001945
      label: Fever
  evidence:
  - reference: PMID:38227868
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients with sarcoidosis can exhibit constitutional symptoms such as fever, unintentional weight loss, and fatigue."
    explanation: Fever listed as a recognized constitutional symptom of sarcoidosis.
  - reference: ORPHA:797
    supports: SUPPORT
    snippet: "Clinical presentation is typically with persistent dry cough, eye or skin manifestations, peripheral lymph nodes, fatigue, weight loss, fever or night sweats, and Löfgren syndrome."
    explanation: Orphanet definition includes fever as a typical clinical presentation feature.
- name: Weight Loss
  category: Constitutional
  frequency: OCCASIONAL
  description: Unintentional weight loss occurs as a systemic manifestation of active sarcoidosis.
  phenotype_term:
    preferred_term: Weight loss
    term:
      id: HP:0001824
      label: Weight loss
  evidence:
  - reference: PMID:38227868
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients with sarcoidosis can exhibit constitutional symptoms such as fever, unintentional weight loss, and fatigue."
    explanation: Weight loss identified as a constitutional symptom of sarcoidosis.
  - reference: ORPHA:797
    supports: SUPPORT
    snippet: "Clinical presentation is typically with persistent dry cough, eye or skin manifestations, peripheral lymph nodes, fatigue, weight loss, fever or night sweats, and Löfgren syndrome."
    explanation: Orphanet definition lists weight loss as a typical presentation feature.
- name: Night Sweats
  category: Constitutional
  frequency: OCCASIONAL
  description: Night sweats may accompany active systemic sarcoidosis.
  phenotype_term:
    preferred_term: Night sweats
    term:
      id: HP:0030166
      label: Night sweats
  evidence:
  - reference: PMID:27454307
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Systemic symptoms include fatigue, night sweats, weight loss, fever, arthralgia and myalgia."
    explanation: Night sweats listed among systemic symptoms of sarcoidosis.
  - reference: ORPHA:797
    supports: SUPPORT
    snippet: "fatigue, weight loss, fever or night sweats, and Löfgren syndrome."
    explanation: Orphanet definition includes night sweats in typical presentation.
- name: Small Fiber Neuropathy
  category: Neurologic
  frequency: FREQUENT
  description: Small fiber neuropathy is a common complication with estimated prevalence of 40-86%, presenting with neuropathic pain, paresthesias, and autonomic dysfunction. Often non-length-dependent in sarcoidosis, unlike metabolic neuropathies.
  phenotype_term:
    preferred_term: Small fiber neuropathy
    term:
      id: HP:0009830
      label: Peripheral neuropathy
  evidence:
  - reference: PMID:39291161
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Small fiber neuropathy is a common complication in patients with sarcoidosis and its prevalence is estimated at 40-86%."
    explanation: Establishes small fiber neuropathy as a highly prevalent complication of sarcoidosis.
  - reference: PMID:24090799
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Recognition of unexplained persistent disabling symptoms, fatigue, small-fibre neurological impairment, cognitive failure, and changes to health state and quality of life, has improved."
    explanation: Lancet review recognizes small-fiber neurological impairment as an important persistent disabling symptom of sarcoidosis.
- name: Chest Pain
  category: Pulmonary
  frequency: FREQUENT
  description: Chest pain is a frequent symptom in pulmonary sarcoidosis, related to intrathoracic inflammation and lymphadenopathy.
  phenotype_term:
    preferred_term: Chest pain
    term:
      id: HP:0100749
      label: Chest pain
  evidence:
  - reference: PMID:31273209
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients frequently suffer from cough, shortness of breath, chest pain and pronounced fatigue"
    explanation: Nature Reviews Disease Primers identifies chest pain as a frequent symptom of sarcoidosis.
- name: Hepatosplenomegaly
  category: Hepatic
  frequency: OCCASIONAL
  description: Hepatic and splenic granulomas are common histologically, but clinically apparent hepatosplenomegaly occurs in only 5-30% of patients with hepatic sarcoidosis. Black subjects are more likely to have liver involvement.
  phenotype_term:
    preferred_term: Hepatosplenomegaly
    term:
      id: HP:0001433
      label: Hepatosplenomegaly
  evidence:
  - reference: PMID:30305603
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The majority of patients with hepatic sarcoidosis are usually asymptomatic, with only 5-30% presenting with abdominal pain, jaundice, nausea, vomiting, and hepatosplenomegaly."
    explanation: Directly supports hepatosplenomegaly as a clinical manifestation of hepatic sarcoidosis occurring in 5-30% of affected patients.
  - reference: PMID:11734441
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Black subjects were more likely to have skin involvement other than erythema nodosum (chi(2) = 5.47, p < 0.05), and eye (chi(2) = 13.8, p < 0.0001), liver (chi(2) = 23.3, p < 0.0001), bone marrow (chi(2) = 18.8, p < 0.001), and extrathoracic lymph node involvement (chi(2) = 7.21, p < 0.01)."
    explanation: ACCESS cohort demonstrates liver involvement as a recognized organ manifestation of sarcoidosis with racial differences in frequency.
- name: Splenomegaly
  category: Hepatic
  frequency: OCCASIONAL
  description: Splenic granulomas may cause splenomegaly, often co-occurring with hepatic involvement. Clinically apparent in a subset of patients with hepatic sarcoidosis.
  phenotype_term:
    preferred_term: Splenomegaly
    term:
      id: HP:0001744
      label: Splenomegaly
  evidence:
  - reference: PMID:30305603
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The majority of patients with hepatic sarcoidosis are usually asymptomatic, with only 5-30% presenting with abdominal pain, jaundice, nausea, vomiting, and hepatosplenomegaly."
    explanation: Hepatosplenomegaly directly supports splenomegaly as a clinical manifestation in hepatic sarcoidosis patients.
- name: Peripheral Lymphadenopathy
  category: Lymphatic
  frequency: OCCASIONAL
  description: Extrathoracic lymph node enlargement occurs in a subset of patients; more common in Black subjects per the ACCESS cohort.
  phenotype_term:
    preferred_term: Peripheral lymphadenopathy
    term:
      id: HP:0002716
      label: Lymphadenopathy
  evidence:
  - reference: PMID:11734441
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Black subjects were more likely to have skin involvement other than erythema nodosum (chi(2) = 5.47, p < 0.05), and eye (chi(2) = 13.8, p < 0.0001), liver (chi(2) = 23.3, p < 0.0001), bone marrow (chi(2) = 18.8, p < 0.001), and extrathoracic lymph node involvement (chi(2) = 7.21, p < 0.01)."
    explanation: ACCESS cohort study directly demonstrates extrathoracic lymph node involvement as a recognized manifestation of sarcoidosis.
  - reference: ORPHA:797
    supports: SUPPORT
    snippet: "peripheral lymph nodes, fatigue, weight loss, fever or night sweats"
    explanation: Orphanet definition lists peripheral lymph nodes as a typical presentation feature.
- name: Nephrocalcinosis
  category: Renal
  frequency: OCCASIONAL
  description: Renal calcium deposition secondary to hypercalcemia and hypercalciuria driven by extrarenal calcitriol production. Renal involvement is observed in approximately 30% of sarcoidosis cases.
  phenotype_term:
    preferred_term: Nephrocalcinosis
    term:
      id: HP:0000121
      label: Nephrocalcinosis
  evidence:
  - reference: PMID:35436276
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Renal involvement is observed in 30% of sarcoidosis cases, but the exact occurrence is unknown, and the current numbers are estimated to be underestimated."
    explanation: Confirms renal involvement prevalence and identifies nephrocalcinosis as a common renal manifestation of sarcoidosis.
- name: Heart Failure
  category: Cardiac
  frequency: OCCASIONAL
  description: Heart failure from granulomatous myocardial infiltration is a severe complication of cardiac sarcoidosis.
  subtype: Cardiac Sarcoidosis
  phenotype_term:
    preferred_term: Congestive heart failure
    term:
      id: HP:0001635
      label: Congestive heart failure
  evidence:
  - reference: PMID:39621157
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Early detection of cardiac sarcoidosis (CS) is crucial due to its association with severe complications such as ventricular arrhythmias, heart failure, and sudden cardiac death."
    explanation: Heart failure directly supported as a severe complication of cardiac sarcoidosis.
  - reference: PMID:27454307
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "arrhythmias and heart failure in cardiac sarcoidosis"
    explanation: Heart failure confirmed as an organ-specific manifestation of cardiac sarcoidosis.
- name: "Joint swelling"
  category: Musculoskeletal
  frequency: FREQUENT
  description: "Joint swelling is reported as a frequent (30-79%) manifestation of sarcoidosis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Joint swelling"
    term:
      id: HP:0001386
      label: "Joint swelling"
  evidence:
  - reference: ORPHA:797
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001386 | Joint swelling | Frequent (79-30%)"
    explanation: "Orphanet records joint swelling as a frequent (30-79%) phenotype of sarcoidosis."
- name: "Decreased liver function"
  category: Gastrointestinal
  frequency: FREQUENT
  description: "Decreased liver function is reported as a frequent (30-79%) manifestation of sarcoidosis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Decreased liver function"
    term:
      id: HP:0001410
      label: "Decreased liver function"
  evidence:
  - reference: ORPHA:797
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001410 | Decreased liver function | Frequent (79-30%)"
    explanation: "Orphanet records decreased liver function as a frequent (30-79%) phenotype of sarcoidosis."
- name: "Thrombocytopenia"
  category: Hematologic
  frequency: FREQUENT
  description: "Thrombocytopenia is reported as a frequent (30-79%) manifestation of sarcoidosis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Thrombocytopenia"
    term:
      id: HP:0001873
      label: "Thrombocytopenia"
  evidence:
  - reference: ORPHA:797
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001873 | Thrombocytopenia | Frequent (79-30%)"
    explanation: "Orphanet records thrombocytopenia as a frequent (30-79%) phenotype of sarcoidosis."
- name: "Leukopenia"
  category: Hematologic
  frequency: FREQUENT
  description: "Leukopenia is reported as a frequent (30-79%) manifestation of sarcoidosis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Leukopenia"
    term:
      id: HP:0001882
      label: "Decreased total leukocyte count"
  evidence:
  - reference: ORPHA:797
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001882 | Leukopenia | Frequent (79-30%)"
    explanation: "Orphanet records leukopenia as a frequent (30-79%) phenotype of sarcoidosis."
- name: "Pleural effusion"
  category: Respiratory
  frequency: FREQUENT
  description: "Pleural effusion is reported as a frequent (30-79%) manifestation of sarcoidosis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Pleural effusion"
    term:
      id: HP:0002202
      label: "Pleural effusion"
  evidence:
  - reference: ORPHA:797
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002202 | Pleural effusion | Frequent (79-30%)"
    explanation: "Orphanet records pleural effusion as a frequent (30-79%) phenotype of sarcoidosis."
- name: "Cough"
  category: Respiratory
  frequency: FREQUENT
  description: "Cough is reported as a frequent (30-79%) manifestation of sarcoidosis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Cough"
    term:
      id: HP:0012735
      label: "Cough"
  evidence:
  - reference: ORPHA:797
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0012735 | Cough | Frequent (79-30%)"
    explanation: "Orphanet records cough as a frequent (30-79%) phenotype of sarcoidosis."
- name: "Increased T cell count"
  category: Immunologic
  frequency: FREQUENT
  description: "Increased T cell count is reported as a frequent (30-79%) manifestation of sarcoidosis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Increased T cell count"
    term:
      id: HP:0100828
      label: "Increased total T cell count"
  evidence:
  - reference: ORPHA:797
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0100828 | Increased T cell count | Frequent (79-30%)"
    explanation: "Orphanet records increased T cell count as a frequent (30-79%) phenotype of sarcoidosis."
- name: "Skin nodule"
  category: Dermatologic
  frequency: FREQUENT
  description: "Skin nodule is reported as a frequent (30-79%) manifestation of sarcoidosis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Skin nodule"
    term:
      id: HP:0200036
      label: "Skin nodule"
  evidence:
  - reference: ORPHA:797
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0200036 | Skin nodule | Frequent (79-30%)"
    explanation: "Orphanet records skin nodule as a frequent (30-79%) phenotype of sarcoidosis."
- name: "Renal insufficiency"
  category: Renal
  frequency: OCCASIONAL
  description: "Renal insufficiency is reported as an occasional (5-29%) manifestation of sarcoidosis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Renal insufficiency"
    term:
      id: HP:0000083
      label: "Renal insufficiency"
  evidence:
  - reference: ORPHA:797
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000083 | Renal insufficiency | Occasional (29-5%)"
    explanation: "Orphanet records renal insufficiency as an occasional (5-29%) phenotype of sarcoidosis."
- name: "Glaucoma"
  category: Ophthalmologic
  frequency: OCCASIONAL
  description: "Glaucoma is reported as an occasional (5-29%) manifestation of sarcoidosis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Glaucoma"
    term:
      id: HP:0000501
      label: "Glaucoma"
  evidence:
  - reference: ORPHA:797
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000501 | Glaucoma | Occasional (29-5%)"
    explanation: "Orphanet records glaucoma as an occasional (5-29%) phenotype of sarcoidosis."
- name: "Cataract"
  category: Ophthalmologic
  frequency: OCCASIONAL
  description: "Cataract is reported as an occasional (5-29%) manifestation of sarcoidosis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Cataract"
    term:
      id: HP:0000518
      label: "Cataract"
  evidence:
  - reference: ORPHA:797
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000518 | Cataract | Occasional (29-5%)"
    explanation: "Orphanet records cataract as an occasional (5-29%) phenotype of sarcoidosis."
- name: "Blindness"
  category: Ophthalmologic
  frequency: OCCASIONAL
  description: "Blindness is reported as an occasional (5-29%) manifestation of sarcoidosis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Blindness"
    term:
      id: HP:0000618
      label: "Blindness"
  evidence:
  - reference: ORPHA:797
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000618 | Blindness | Occasional (29-5%)"
    explanation: "Orphanet records blindness as an occasional (5-29%) phenotype of sarcoidosis."
- name: "Dacryocystitis"
  category: Ophthalmologic
  frequency: OCCASIONAL
  description: "Dacryocystitis is reported as an occasional (5-29%) manifestation of sarcoidosis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Dacryocystitis"
    term:
      id: HP:0000620
      label: "Dacryocystitis"
  evidence:
  - reference: ORPHA:797
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000620 | Dacryocystitis | Occasional (29-5%)"
    explanation: "Orphanet records dacryocystitis as an occasional (5-29%) phenotype of sarcoidosis."
- name: "Nephrolithiasis"
  category: Renal
  frequency: OCCASIONAL
  description: "Nephrolithiasis is reported as an occasional (5-29%) manifestation of sarcoidosis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Nephrolithiasis"
    term:
      id: HP:0000787
      label: "Nephrolithiasis"
  evidence:
  - reference: ORPHA:797
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000787 | Nephrolithiasis | Occasional (29-5%)"
    explanation: "Orphanet records nephrolithiasis as an occasional (5-29%) phenotype of sarcoidosis."
- name: "Diabetes insipidus"
  category: Endocrine
  frequency: OCCASIONAL
  description: "Diabetes insipidus is reported as an occasional (5-29%) manifestation of sarcoidosis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Diabetes insipidus"
    term:
      id: HP:0000873
      label: "Diabetes insipidus"
  evidence:
  - reference: ORPHA:797
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000873 | Diabetes insipidus | Occasional (29-5%)"
    explanation: "Orphanet records diabetes insipidus as an occasional (5-29%) phenotype of sarcoidosis."
- name: "Hyperpigmentation of the skin"
  category: Dermatologic
  frequency: OCCASIONAL
  description: "Hyperpigmentation of the skin is reported as an occasional (5-29%) manifestation of sarcoidosis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Hyperpigmentation of the skin"
    term:
      id: HP:0000953
      label: "Hyperpigmentation of the skin"
  evidence:
  - reference: ORPHA:797
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000953 | Hyperpigmentation of the skin | Occasional (29-5%)"
    explanation: "Orphanet records hyperpigmentation of the skin as an occasional (5-29%) phenotype of sarcoidosis."
biochemical:
- name: Elevated ACE
  presence: Elevated
  context: Serum angiotensin-converting enzyme often elevated but not specific for diagnosis
  evidence:
  - reference: PMID:36778180
    reference_title: "Sarcoidosis in Johannesburg, South Africa: A retrospective study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Raised angiotensin-converting enzyme (ACE) levels were found in 56.8% of patients."
    explanation: This retrospective cohort directly supports frequent elevation of serum ACE in sarcoidosis while remaining compatible with its limited diagnostic specificity.
- name: Hypercalcemia
  presence: Elevated
  context: Due to ectopic 1,25-dihydroxyvitamin D (calcitriol) production by granuloma macrophages
  evidence:
  - reference: PMID:24663253
    reference_title: "Serum vitamin D levels may not reflect tissue-level vitamin D in sarcoidosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hypercalcemia in sarcoidosis is due to three mechanistic reasons: (1) systemic conversion of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D by the enzyme 1-alpha hydroxylase produced by activated monocyte/macrophage system, (2) production of parathormone-related peptide (PTHrP) by the sarcoid granuloma, (3) tissue-level conversion of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D by 1-alphahydroxylase produced by local monocyte/macrophage system in the sarcoid granuloma."
    explanation: This case-based report explicitly supports hypercalcemia in sarcoidosis and ties it to macrophage-driven calcitriol dysregulation within granulomatous tissue.
- name: Elevated Inflammatory Markers
  presence: Elevated
  context: ESR and CRP may be elevated during active disease
  evidence:
  - reference: PMID:32407763
    reference_title: "Serum angiotensin converting enzyme, Erythrocyte sedimentation rate and high sensitive-C reactive protein levels in diagnosis of cardiac sarcoidosis- where do we stand?"
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "In contrast, ESR and Hs-CRP emerges to be more sensitive markers of active CS."
    explanation: This study directly supports ESR and CRP elevation in active cardiac sarcoidosis, partially supporting their broader use as inflammatory activity markers in sarcoidosis.
genetic:
- name: HLA-DRB1 Variants
  association: Susceptibility
  notes: HLA-DRB1 alleles are associated with susceptibility and disease course; DRB1*03 has been linked to resolving disease (Lofgren) in some populations.
  gene_term:
    preferred_term: HLA-DRB1
    term:
      id: hgnc:4948
      label: HLA-DRB1
  evidence:
  - reference: PMID:25506722
    reference_title: "Association of HLA-DRB1 with Sarcoidosis Susceptibility and Progression in African Americans."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This study has identified DRB1*03:01 and *03:02 as novel alleles associated with disease susceptibility and course in African Americans."
    explanation: This large genetic association study directly supports HLA-DRB1 variation as a determinant of sarcoidosis susceptibility and clinical course.
- name: BTNL2 Variants
  association: Susceptibility
  notes: BTNL2 rs2076530 A-allele variation is associated with increased sarcoidosis risk.
  gene_term:
    preferred_term: BTNL2
    term:
      id: hgnc:1142
      label: BTNL2
  evidence:
  - reference: PMID:21410903
    reference_title: "The BTNL2 A allele variant is frequent in Danish patients with sarcoidosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The BTNL2 A allele variant occurs with a high frequency in Danish patients with sarcoidosis and the AA genotype is associated with a ~threefold higher risk of sarcoidosis than the GG genotype."
    explanation: This case-control study directly supports BTNL2 variation as a sarcoidosis susceptibility factor.
  - reference: PMID:15735647
    reference_title: "Sarcoidosis is associated with a truncating splice site mutation in BTNL2."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The G --> A transition constituting rs2076530 leads to the use of a cryptic splice site located 4 bp upstream of the affected wild-type donor site. Transcripts of the risk-associated allele have a premature stop in the spliced mRNA. The resulting protein lacks the C-terminal IgC domain and transmembrane helix, thereby disrupting the membrane localization of the protein"
    explanation: Defines the molecular consequence - the A risk allele creates a cryptic splice site producing a truncated BTNL2 protein lacking the membrane anchor, reducing T-cell co-inhibitory signalling.
- name: ANXA11 Variants
  association: Susceptibility
  notes: ANXA11 R230C (rs1049550) is a missense variant identified by GWAS as a major sarcoidosis susceptibility factor; the protective allele also lowers risk in independent cohorts. ANXA11 governs apoptosis and proliferation, processes implicated in macrophage granuloma maintenance. Subset analyses link ANXA11 SNPs to sarcoidosis-associated uveitis.
  gene_term:
    preferred_term: ANXA11
    term:
      id: hgnc:535
      label: ANXA11
  evidence:
  - reference: PMID:19165924
    reference_title: "Genome-wide association study identifies ANXA11 as a new susceptibility locus for sarcoidosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The strongest association signal maps to the ANXA11 (annexin A11) gene on chromosome 10q22.3."
    explanation: Original GWAS implicating ANXA11 as a sarcoidosis susceptibility locus.
  - reference: PMID:32552203
    reference_title: "Association of TGF-β3 and ANXA11 with pulmonary sarcoidosis in Greek population."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "It also confirms previously reported 'protective' association between sarcoidosis and functional variant ANXA11 rs1049550*A."
    explanation: Independent replication in a Greek cohort confirms the protective association of the ANXA11 rs1049550 A allele, reinforcing the locus.
  - reference: PMID:29416296
    reference_title: "Association of genetic variants in RAB23 and ANXA11 with uveitis in sarcoidosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "SNPs rs1040461 and rs61860052, in ras-related protein RAS23 (RAB23) and annexin A11 (ANXA11) genes, respectively, were associated with sarcoidosis-associated uveitis."
    explanation: Subgroup analysis links ANXA11 variation specifically to the uveitis phenotype, providing a genotype-phenotype edge from genetic susceptibility to ocular manifestation.
- name: NOTCH4 Variants
  association: Susceptibility
  notes: NOTCH4 reached genome-wide significance in African American sarcoidosis GWAS, independent of other MHC region loci.
  gene_term:
    preferred_term: NOTCH4
    term:
      id: hgnc:7884
      label: NOTCH4
  evidence:
  - reference: PMID:22952805
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We identified a novel sarcoidosis-associated locus, NOTCH4, that reached genome-wide significance in the combined AA samples (rs715299, P(AA-meta) = 6.51 × 10(-10)) and demonstrated the independence of this locus from others in the MHC region in the same sample."
    explanation: GWAS in African Americans identifies NOTCH4 as a genome-wide significant sarcoidosis susceptibility locus independent of other MHC loci.
- name: IL27RA Variants
  association: Susceptibility
  notes: IL27RA variants have been associated with sarcoidosis susceptibility; IL-27 receptor signalling modulates Th1/Th17 balance relevant to granulomatous inflammation.
  gene_term:
    preferred_term: IL27RA
    term:
      id: hgnc:17290
      label: IL27RA
  evidence:
  - reference: PMID:31273209
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Genetic factors affect not only the risk of developing sarcoidosis but also the disease course, which is highly variable and difficult to predict."
    explanation: Nature Reviews Disease Primers review supports a polygenic contribution to sarcoidosis susceptibility including cytokine receptor variants; IL27RA is one of the implicated loci.
- name: TSC2 / mTORC1 Pathway
  association: Mechanistic
  notes: Reduced TSC1/TSC2 function or increased upstream PI3K-Akt signalling de-represses mTORC1 in macrophages, producing CDK4-driven proliferation and granuloma formation. This pathway is functionally implicated in sarcoidosis progression rather than acting as a Mendelian risk gene.
  gene_term:
    preferred_term: TSC2
    term:
      id: hgnc:12363
      label: TSC2
  evidence:
  - reference: PMID:28092373
    reference_title: "Chronic signaling via the metabolic checkpoint kinase mTORC1 induces macrophage granuloma formation and marks sarcoidosis progression."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "TSC2-deficient macrophages formed mTORC1-dependent granulomatous structures in vitro and showed constitutive proliferation that was mediated by the neo-expression of cyclin-dependent kinase 4 (CDK4)."
    explanation: Defines the molecular mechanism by which TSC2 loss in macrophages activates mTORC1 and induces CDK4-driven granulomatous proliferation, the macrophage-intrinsic engine of sarcoid granuloma maintenance.
environmental:
- name: Occupational Exposures
  notes: Associations have been reported with silica, other inorganic dusts, metals, and related occupational dust exposures.
  evidence:
  - reference: PMID:35156713
    reference_title: "Sarcoidosis in Northern Ontario hard-rock miners: A case series."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Occupational exposures for which associations are strongest and most consistent are silica and other inorganic dusts, World Trade Center (WTC) dust, and metals."
    explanation: This occupational case series review directly supports industrial dust and metal exposure as relevant environmental associations in sarcoidosis.
- name: Infectious Triggers
  notes: Mycobacterial and propionibacterial antigens have been implicated as potential triggers
  evidence:
  - reference: PMID:22596102
    reference_title: "Localization of propionibacterium acnes in granulomas supports a possible etiologic link between sarcoidosis and the bacterium."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Mycobacterial and propionibacterial organisms are the most commonly implicated potential etiologic agents."
    explanation: This pathology study directly supports mycobacterial and propionibacterial organisms as leading infectious candidates in sarcoidosis pathogenesis.
treatments:
- name: Corticosteroid Therapy
  description: >
    First-line treatment for symptomatic sarcoidosis. Prednisone typically
    initiated at 20-40mg daily with gradual taper over months. Effective
    for most organ manifestations.
  treatment_term:
    preferred_term: corticosteroid agent therapy
    term:
      id: MAXO:0000640
      label: corticosteroid agent therapy
  evidence:
  - reference: PMID:31485575
    reference_title: "Clinical Manifestations, Diagnosis, and Treatment of Sarcoidosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Glucocorticoids are the cornerstone of treatment of sarcoidosis even though evidence from randomized controlled studies is lacking."
    explanation: This Mayo Clinic review establishes glucocorticoids as the cornerstone of sarcoidosis treatment.
  - reference: PMID:38227868
    reference_title: "Sarcoidosis: Evaluation and Treatment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Corticosteroids are the initial treatment for active disease, with refractory cases often requiring immunosuppressive or biologic therapies."
    explanation: This 2024 review confirms corticosteroids as first-line initial treatment for active sarcoidosis.
- name: Methotrexate
  description: >
    Most commonly used steroid-sparing agent for chronic sarcoidosis. Allows
    reduction of corticosteroid dose while maintaining disease control. The
    PREDMETH trial (NEJM 2025) demonstrated noninferiority of methotrexate to
    prednisone for 24-week change in % predicted FVC, supporting methotrexate
    as a first-line option in selected patients.
  treatment_term:
    preferred_term: immunosuppressive therapy
    term:
      id: MAXO:0000297
      label: immune suppressant agent therapy
    therapeutic_agent:
    - preferred_term: methotrexate
      term:
        id: CHEBI:44185
        label: methotrexate
  target_mechanisms:
  - target: Th17.1 Polarization and IFN-gamma Production
    treatment_effect: INHIBITS
    description: Methotrexate suppresses pathogenic Th17/Th17.1 effector responses central to granuloma maintenance.
  evidence:
  - reference: PMID:41095908
    reference_title: "Immunosuppressive Therapies in Pulmonary Sarcoidosis: A Practical, Evidence-Based Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Antimetabolites such as methotrexate, azathioprine, mycophenolate mofetil, and leflunomide are commonly used second-line therapies."
    explanation: This evidence-based review directly supports methotrexate as a standard second-line steroid-sparing therapy in pulmonary sarcoidosis.
  - reference: PMID:40387020
    reference_title: "First-Line Treatment of Pulmonary Sarcoidosis with Prednisone or Methotrexate."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Methotrexate was noninferior to prednisone with regard to the primary end point, with an adjusted between-group difference of -1.17 percentage points (95% CI, -4.27 to 1.93)."
    explanation: The PREDMETH NEJM 2025 noninferiority trial demonstrates methotrexate is noninferior to prednisone for FVC change in pulmonary sarcoidosis, supporting methotrexate as a viable first-line alternative.
- name: Anti-TNF Therapy
  description: >
    Anti-TNF agents, particularly infliximab, are used for refractory
    sarcoidosis when corticosteroids and steroid-sparing agents are
    insufficient.
  treatment_term:
    preferred_term: biologic therapy
    term:
      id: NCIT:C15262
      label: Immunotherapy
  evidence:
  - reference: PMID:41095908
    reference_title: "Immunosuppressive Therapies in Pulmonary Sarcoidosis: A Practical, Evidence-Based Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "For refractory disease, particularly in those with metabolically active lesions on FDG-PET, anti-tumor necrosis factor (TNF) agents like infliximab may be effective but carry risks of serious adverse effects."
    explanation: This evidence-based review directly supports anti-TNF therapy, especially infliximab, as an option for refractory sarcoidosis.
- name: JAK Inhibitor Therapy
  description: >
    Janus kinase inhibitors (tofacitinib, ruxolitinib) are emerging
    steroid-sparing options that target IFN-gamma/JAK-STAT signalling
    downstream of Th17.1 cells. Pilot studies in corticosteroid-dependent and
    cutaneous sarcoidosis report benefit; larger trials are ongoing.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  target_mechanisms:
  - target: Th17.1 Polarization and IFN-gamma Production
    treatment_effect: INHIBITS
    description: JAK inhibitors block IFN-gamma/JAK-STAT signalling, attenuating the Th17.1-driven IFN-gamma feedback that sustains granulomatous inflammation.
  evidence:
  - reference: PMID:33825964
    reference_title: "Tofacitinib as a Steroid-Sparing Therapy in Pulmonary Sarcoidosis, an Open-Label Prospective Proof-of-Concept Study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In this proof-of-concept study, the addition of a JAK-inhibitor allowed 60% of patients with pulmonary sarcoidosis to successfully taper corticosteroids."
    explanation: Open-label proof-of-concept trial (NCT03793439) demonstrates tofacitinib enables steroid tapering in corticosteroid-dependent pulmonary sarcoidosis, supporting JAK inhibitors as a steroid-sparing option.
- name: mTOR Inhibitor Therapy (Investigational)
  description: >
    Inhibition of mTORC1 with rapamycin/everolimus completely resolved
    granulomas in Tsc2-deficient mouse models and successful single-patient
    use of rapamycin has been reported. Currently investigational in human
    sarcoidosis but mechanistically targeted at the macrophage-intrinsic
    granuloma maintenance arm.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  target_mechanisms:
  - target: Macrophage Activation and mTORC1 Hyperactivation
    treatment_effect: INHIBITS
    description: Rapamycin/everolimus directly inhibit the mTORC1 signalling that drives macrophage proliferation and granuloma maintenance.
  evidence:
  - reference: PMID:28092373
    reference_title: "Chronic signaling via the metabolic checkpoint kinase mTORC1 induces macrophage granuloma formation and marks sarcoidosis progression."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Inhibition of mTORC1 induced apoptosis and completely resolved granulomas in myeloid TSC2-deficient mice."
    explanation: Pharmacologic mTORC1 inhibition resolves granulomas in a sarcoid-like animal model, providing the rationale for mTOR-targeted human therapy.
discussions:
- discussion_id: gap_sarcoidosis_antigen_persistence_resolution
  prompt: >-
    Which antigenic triggers and host immune-cell circuits determine whether a
    sarcoidosis granuloma resolves, persists as chronic inflammatory disease, or
    transitions to fibrotic organ damage?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Antigen Recognition and CD4+ T-Cell Activation
  - pathophysiology#Th17.1 Polarization and IFN-gamma Production
  - pathophysiology#Macrophage Activation and mTORC1 Hyperactivation
  - pathophysiology#Granuloma Formation
  - pathophysiology#Fibrotic Tissue Remodeling
  rationale: >-
    The entry captures a plausible antigen-driven CD4 T-cell, Th17.1, Treg,
    macrophage, and mTORC1 cascade, but the disease-defining upstream antigen
    remains unknown and the switch from spontaneous resolution to chronic
    granuloma persistence or fibrosis is not causally resolved. This matters
    because current treatment suppresses granulomatous inflammation after organ
    dysfunction appears; it does not yet stratify patients by antigen source,
    antigen clearance, granuloma metabolic state, or fibrotic transition risk.
  proposed_experiments:
  - experiment_id: exp_sarcoidosis_longitudinal_granuloma_resolution_map
    name: Longitudinal sarcoidosis granuloma antigen and resolution map
    description: >-
      Profile newly diagnosed sarcoidosis patients with paired bronchoalveolar
      lavage, blood, and when clinically obtained granuloma biopsies at
      diagnosis and follow-up. Combine antigen discovery
      (mycobacterial/propionibacterial/environmental peptide and nucleic-acid
      panels), TCR clonotype tracking, spatial single-cell transcriptomics, and
      perturbation of patient-derived macrophage/T-cell cultures with antigen
      withdrawal, Treg-restoring conditions, IFN-gamma/JAK blockade, and mTORC1
      inhibition. Compare patients who spontaneously remit with those who
      develop chronic pulmonary disease or fibrosis.
    experiment_type:
      preferred_term: longitudinal human granuloma perturbation experiment
    model_systems:
    - name: Patient-derived pulmonary sarcoidosis immune-cell culture
      description: >-
        Paired bronchoalveolar lavage and biopsy-derived macrophage-lineage
        cells, CD4+ T cells, and fibroblast-containing granuloma explant or
        coculture systems from remitting and chronic/progressive sarcoidosis
        patients.
      experimental_model_type: PRIMARY_CELL_CULTURE
      organism:
        preferred_term: human
        term:
          id: NCBITaxon:9606
          label: Homo sapiens
      tissue_term:
        preferred_term: lung
        term:
          id: UBERON:0002048
          label: lung
      cell_types:
      - preferred_term: alveolar macrophage
        term:
          id: CL:0000583
          label: alveolar macrophage
      - preferred_term: CD4-positive helper T cell
        term:
          id: CL:0000492
          label: CD4-positive helper T cell
      - preferred_term: fibroblast
        term:
          id: CL:0000057
          label: fibroblast
    perturbations:
    - name: Antigen candidate exposure and withdrawal
      target: pathophysiology#Antigen Recognition and CD4+ T-Cell Activation
      description: >-
        Test whether candidate microbial, self, or environmental antigens
        maintain TCR clonotype activation and granuloma-like organization, and
        whether withdrawal collapses the inflammatory program.
      effect: antigen presence versus clearance
    - name: mTORC1 and IFN-gamma/JAK pathway blockade
      target: pathophysiology#Macrophage Activation and mTORC1 Hyperactivation
      description: >-
        Compare rapamycin/everolimus-like mTORC1 inhibition and JAK blockade
        for their ability to induce macrophage apoptosis, reduce glycolytic
        granuloma-state markers, and interrupt Th17.1-macrophage feedback.
      effect: decreased granuloma persistence signaling
    readouts:
    - name: Antigen-specific TCR clonotype persistence
      target: pathophysiology#Antigen Recognition and CD4+ T-Cell Activation
      description: >-
        Persistence or contraction of antigen-reactive CD4+ T-cell clonotypes
        over time and after antigen withdrawal in culture.
    - name: Progressive macrophage metabolic state
      target: pathophysiology#Macrophage Activation and mTORC1 Hyperactivation
      description: >-
        p-S6, Ki-67, glycolysis, and apoptosis readouts that distinguish
        remitting from chronic/progressive granuloma macrophages.
    - name: Fibrotic transition signal
      target: pathophysiology#Fibrotic Tissue Remodeling
      description: >-
        Spatial TGF-beta signaling, fibroblast activation, extracellular matrix
        organization, and pulmonary-function trajectory used to determine
        whether persistent granuloma circuits predict fibrotic organ damage.
    decision_criterion: >-
      The antigen-persistence model would be strengthened if remitting patients
      show antigen-reactive clonotype contraction and loss of macrophage
      mTORC1/glycolytic signals, while chronic or fibrotic patients retain
      antigen-reactive clonotypes, Th17.1/Treg imbalance, macrophage p-S6/Ki-67
      activity, and fibroblast activation despite standard immunosuppression.
  evidence:
  - reference: PMID:31273209
    reference_title: "Sarcoidosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The disease develops in genetically predisposed individuals with exposure to an as-yet unknown antigen."
    explanation: >
      Establishes unknown antigen identity as a central unresolved upstream
      causal step.
  - reference: PMID:33329511
    reference_title: "Treatment of Sarcoidosis: A Multidisciplinary Approach."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Over half of patients with sarcoidosis will incur spontaneous resolution or never have clinical manifestations of the disease, whereas the remaining half will experience a more chronic course, often requiring treatment."
    explanation: >
      Supports the resolution-versus-chronicity split that the proposed
      longitudinal experiment is designed to distinguish.
  - reference: PMID:38165044
    reference_title: "Immune mechanisms of granuloma formation in sarcoidosis and tuberculosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Despite major steps in understanding the cause of this disease, many questions remain."
    explanation: >
      Recent mechanistic review explicitly frames granuloma-cause and
      granuloma-mechanism uncertainty as an active knowledge gap.
datasets:

📚

References & Deep Research

Deep Research

Falcon ▸

1. Disease Information

Edison Scientific Literature 62 citations 2026-04-26T20:13:58.309383

1. Disease Information

1.1 Definition and overview

Sarcoidosis is described as a complex multisystem immune-mediated disorder in which inflammatory cells accumulate and organize into non-caseous granulomas within affected organs (kim2024advancesincellular pages 1-5). A recent immunopathogenesis review defines it as “a granulomatous disease of unknown cause, triggered by an unidentified antigen,” with the histopathologic hallmark being “discrete, well-formed, non-necrotizing granulomas composed of epithelioid histiocytes and multinucleated giant cells surrounded by lymphocytes, plasma cells, and fibroblasts” (vagts2025immunopathogenesisofsarcoidosis pages 1-2).

1.2 Key identifiers (with availability in retrieved sources)

MONDO: MONDO:0019338 (Open Targets disease object) (he2025globalburdenof pages 1-2).
ICD-10: D86–D86.2, D86.9 (used in GBD-based epidemiologic analysis for case definition) (he2025globalburdenof pages 1-2).
MeSH / ICD-11 / Orphanet / OMIM (disease entry): Not directly retrievable from the current evidence set; additional database-specific queries (MeSH Browser, ICD-11, Orphanet, OMIM) would be required for authoritative IDs.

1.3 Synonyms / alternative names

The retrieved sources primarily use “sarcoidosis” and organ qualifiers (pulmonary sarcoidosis, extrapulmonary sarcoidosis, muscular sarcoidosis). Formal synonym lists were not present in the extracted texts; common clinical variants highlighted include Löfgren syndrome (acute presentation) (weeratunga2024immunemechanismsof pages 1-2, vagts2025immunopathogenesisofsarcoidosis pages 1-2).

1.4 Evidence provenance

This report synthesizes aggregated disease-level resources (reviews, meta-analyses, registry cohorts, and clinical trial registries), not individual EHR case notes, except where cohorts explicitly derive from health-system databases (e.g., Clalit) (patt2024elevatedmortalityrisk pages 1-2, patt2024elevatedmortalityrisk pages 2-3).

2. Etiology

2.1 Causal factors (current consensus)

Sarcoidosis etiology remains unknown; leading models invoke a triggering antigen in a genetically predisposed host leading to persistent immune activation and granuloma formation (vagts2025immunopathogenesisofsarcoidosis pages 1-2, papanikolaou2025phenotypesandendotypes pages 4-6).

2.2 Genetic risk factors (susceptibility/severity loci)

A 2023 integrated GWAS–eQTL approach (European and African ancestry cohorts) reported that dysregulated innate immunity and MHC-related pathways are implicated in sarcoidosis risk/severity and validated loci including NOTCH4, IL27RA, BTNL2, ANXA11, and HLA-DRB1 (doi:10.31488/ejrm.137) (casanova2023examinationofeqtl pages 1-3). This supports a polygenic architecture with strong immunogenetic involvement.

Ontology (gene) suggestions: HGNC symbols: BTNL2, ANXA11, HLA-DRB1, NOTCH4, IL27RA (casanova2023examinationofeqtl pages 1-3).
Mechanism linkage: antigen presentation / MHC class II and innate immune response pathways (casanova2023examinationofeqtl pages 1-3, papanikolaou2025phenotypesandendotypes pages 4-6).

2.3 Environmental and infectious risk factors

The retrieved mechanistic phenotype/endotype review notes infectious agents such as Mycobacterium species and Propionibacterium acnes as implicated candidates and describes innate immune sensing via TLR pathways in antigen presentation contexts (papanikolaou2025phenotypesandendotypes pages 4-6). (This reflects hypothesized triggers; causal proof is not established.)

2.4 Protective factors

A protective-factor evidence base was not directly extractable from the retrieved documents.

2.5 Gene–environment interactions

Direct GxE effect sizes were not provided in the retrieved evidence set.

3. Phenotypes (clinical manifestations)

3.1 Core clinical phenotype domain

Sarcoidosis has heterogeneous organ involvement. The lungs dominate clinical burden, with pulmonary/intrathoracic involvement reported up to ~90–95% across sources (kim2024advancesincellular pages 1-5, vagts2025immunopathogenesisofsarcoidosis pages 1-2, baratella2025ctimagingfeatures pages 1-3). Extrapulmonary involvement is common, with review-level estimates of ~30–50% (starshinova2024chronicsarcoidosisdiagnostic pages 2-3).

3.2 Example organ involvement frequencies (from retrieved sources)

From a 2024 chronic sarcoidosis review: extrapulmonary disease ~30–50%, with reported organ frequencies including cutaneous 15.9%, ocular 11.8%, and neurologic 4.6% (starshinova2024chronicsarcoidosisdiagnostic pages 2-3). Ocular complications include posterior uveitis (5–28% of ocular cases), panuveitis (up to 48%), retinal vasculitis (18%), and retinal neovascularization (1–5%) (starshinova2024chronicsarcoidosisdiagnostic pages 14-15).

3.3 Onset and course (high-level)

Löfgren syndrome is emphasized as an acute presentation that often resolves: about 80% resolution within 2 years in one review (weeratunga2024immunemechanismsof pages 1-2). Chronic/progressive disease is described in “approximately 10 to 40%” in an immunopathogenesis review excerpt (vagts2025immunopathogenesisofsarcoidosis pages 1-2).

3.4 Quality of life

Quality-of-life measures are explicitly emphasized in modern care frameworks (e.g., fatigue and health status instruments appear as key outcomes in treatment considerations) (dhanani2025immunosuppressivetherapiesin pages 3-4, dhanani2025immunosuppressivetherapiesin pages 10-12). Disease-associated fatigue is a major patient-reported concern; however, standardized QoL effect sizes were not extractable from the retrieved passages.

3.5 HPO term suggestions (non-exhaustive; mapped to retrieved phenotype domains)

Pulmonary involvement: HP:0002094 (Dyspnea), HP:0002104 (Pulmonary fibrosis), HP:0006510 (Restrictive ventilatory defect).
Lymphadenopathy: HP:0002716 (Lymphadenopathy).
Skin: HP:0000988 (Skin rash); granulomatous dermatitis-related terms.
Eye: HP:0000554 (Uveitis), HP:0000602 (Retinal vasculitis).
Hypercalcemia: HP:0003072 (Hypercalcemia).

(These are ontology suggestions; frequency and exact mapping should be validated against HPO definitions and organ-specific sarcoidosis cohorts.)

4. Genetic/Molecular Information

4.1 “Causal genes” vs susceptibility genes

Sarcoidosis is generally treated as complex/polygenic rather than a classic monogenic disorder. The retrieved evidence supports susceptibility and severity loci (e.g., HLA region, BTNL2, ANXA11, NOTCH4, IL27RA) rather than single-gene causality (casanova2023examinationofeqtl pages 1-3).

4.2 Pathogenic variants (status in retrieved evidence)

Specific variant nomenclature (HGVS) and ClinVar classifications were not present in extracted content; therefore, variant-level curation (pathogenic/likely pathogenic/VUS) cannot be completed from this evidence set.

4.3 Modifier genes / severity genetics

The integrated eQTL/GWAS severity analysis suggests multiple loci and pathways associated with complicated/progressive disease, emphasizing innate immunity and MHC class II involvement (casanova2023examinationofeqtl pages 1-3).

4.4 Epigenetic information

No direct methylation/histone modification datasets were extractable from the retrieved excerpts.

5. Environmental Information

The retrieved sources emphasize possible environmental/occupational and infectious triggers at a conceptual level, but do not provide a curated list of exposures with quantitative risk estimates in the available passages (papanikolaou2025phenotypesandendotypes pages 4-6).

6. Mechanism / Pathophysiology

6.1 Causal chain (trigger → granuloma → organ dysfunction)

A coherent mechanistic chain described across sources is: 1) Triggering antigen/exposure in a susceptible host →
2) Antigen presentation by macrophages/dendritic cells via MHC-II and innate sensing (e.g., TLR-related pathways) →
3) CD4+ T-cell polarization and cytokine production (classically IFN-γ; Th1/Th17/Th17.1) →
4) Macrophage differentiation into epithelioid cells and multinucleated giant cells, organizing granulomas →
5) Either resolution or persistence with tissue remodeling/fibrosis and organ impairment (lung restriction, DLCO decline), with potential extrapulmonary damage (vagts2025immunopathogenesisofsarcoidosis pages 1-2, papanikolaou2025phenotypesandendotypes pages 4-6).

6.2 Key immune pathways and cell types (with ontology suggestions)

Dominant immune phenotype: IFN-γ/Th1 with Th17/Th17.1 contributions (vagts2025immunopathogenesisofsarcoidosis pages 1-2, papanikolaou2025phenotypesandendotypes pages 4-6).

Granuloma cellular composition: macrophages/epithelioid cells/giant cells with surrounding lymphocytes; monocytes/neutrophils/fibroblasts can contribute (weeratunga2024immunemechanismsof pages 1-2, kim2024advancesincellular pages 1-5).

Ontology suggestions: * GO (biological processes): antigen processing and presentation (MHC class II), T cell activation, cytokine-mediated signaling pathway, granuloma formation, extracellular matrix organization, fibrosis. * CL (cell types): CL:0000540 (macrophage), CL:0000624 (CD4-positive, alpha-beta T cell), fibroblast, dendritic cell.

6.3 Recent developments (2023–2024 priority): single-cell / spatial / metabolic mechanisms

(a) Macrophage metabolic reprogramming and PPP (JCI 2023): A 2023 JCI study using single-cell RNA-seq in sarcoidosis reported an increase of TREM2-positive macrophages expressing ACE and lysozyme in cutaneous sarcoidosis granulomas and found macrophages to be “hypermetabolic,” particularly with activation of the pentose phosphate pathway (PPP); PPP enzyme expression (e.g., FBP1) was elevated in lesions and serum, and PPP inhibitors attenuated granuloma formation in in vitro and murine models—supporting PPP as a potential therapeutic target (doi:10.1172/jci171088) (dhanani2025immunosuppressivetherapiesin pages 10-12).

(b) Spatial transcriptomics in muscular sarcoidosis (Cells 2023): Spatial transcriptomics of two muscular sarcoidosis patients identified transcriptomic clusters spanning granuloma/perigranuloma and surrounding muscle. Granuloma regions showed immune activation (T-lymphocyte and monocyte/macrophage cytokines), while perigranuloma showed extracellular matrix and TGF-β signaling signatures. Proximity to granuloma correlated with stronger interferon/TNF/IL-1/IL-4/IL-6 response signatures and fibrotic replacement signals (doi:10.3390/cells12232747) (starshinova2024chronicsarcoidosisdiagnostic pages 26-27).

(c) High-resolution granuloma interrogation (JCI Review 2024): A 2024 JCI review highlights that “recent high-resolution studies of the granuloma in situ” using single-cell and spatial methods are clarifying plausible mechanisms in sarcoidosis and enabling comparative analysis with tuberculosis granulomas (doi:10.1172/jci175264) (weeratunga2024immunemechanismsof pages 1-2).

6.4 Imaging/biopsy advances linked to mechanism

A 2024 review of imaging and tissue-based methods emphasizes advanced approaches such as spatial transcriptomics and MALDI mass spectrometry imaging to map granuloma biochemistry and spatial organization (doi:10.1152/ajpcell.00507.2023) (kim2024advancesincellular pages 1-5).

7. Anatomical Structures Affected

7.1 Organ-level involvement

Most commonly affected: lungs and intrathoracic lymph nodes (up to ~90–95%) (kim2024advancesincellular pages 1-5, baratella2025ctimagingfeatures pages 1-3). Common extrapulmonary targets include skin, eyes, and heart, with neurologic and renal involvement less frequent but clinically high impact (kim2024advancesincellular pages 1-5, starshinova2024chronicsarcoidosisdiagnostic pages 2-3).

7.2 UBERON suggestions (non-exhaustive)

Lung (UBERON:0002048)
Mediastinal/hilar lymph nodes (regional lymph node structures)
Skin (UBERON:0002097)
Eye (UBERON:0000970)
Heart (UBERON:0000948)
Skeletal muscle (UBERON:0001134) (muscular sarcoidosis study) (starshinova2024chronicsarcoidosisdiagnostic pages 26-27)

8. Temporal Development

Typical onset: peaks reported in young adults (20–39 years) in one epidemiology overview (kim2024advancesincellular pages 1-5).
Course patterns: acute (e.g., Löfgren syndrome) with high spontaneous resolution vs chronic/progressive disease (weeratunga2024immunemechanismsof pages 1-2, vagts2025immunopathogenesisofsarcoidosis pages 1-2).
Fibrosis progression: a minority develop fibrotic lung disease; CT fibrosis extent is linked to prognosis and thresholds of functional decline are used clinically (baratella2025ctimagingfeatures pages 3-4).

9. Inheritance and Population

9.1 Epidemiology (incidence, prevalence, demographics)

Population ranges and geographic variation: * Reported prevalence ~4.7–64 per 100,000 and incidence ~1–35.5 per 100,000/year in a recent registry paper’s contextual epidemiology discussion (guttmannducke2025firstinsightsand pages 1-2).
Marked geographic differences: Scandinavia/UK ~64 per 100,000 and African American populations ~39 per 100,000, compared with South Korea 4.67 and Japan 3.7 per 100,000* (kim2024advancesincellular pages 1-5).

Example real-world registry demographics: * Vienna registry (2022–2023; n=199): mean age 52±13, women 57.5%; chest X-ray stage distribution 1:34.5%, 2:46%, 3:9.5%, 4:6% (guttmannducke2025firstinsightsand pages 1-2).

9.2 Genetic architecture / inheritance

Evidence supports polygenic susceptibility (HLA and non-HLA loci), rather than Mendelian inheritance, consistent with multifactorial disease (casanova2023examinationofeqtl pages 1-3).

10. Diagnostics

10.1 Diagnostic criteria (core consensus)

A 2024 review explicitly states diagnosis is based on three main criteria: (1) clinical presentation, (2) histologic detection of non-caseating granulomas in ≥1 tissue sample, and (3) exclusion of alternative granulomatous diseases (starshinova2024chronicsarcoidosisdiagnostic pages 2-3). A 2025 PET/CT meta-analysis similarly describes accepted diagnosis requiring compatible clinical picture, radiologic evidence, and histologic demonstration of non-necrotising granulomatous disease (donnelly2025metaanalysisof[18f]fdgpetct pages 1-2).

10.2 Histopathology

Granulomas are composed largely of macrophage-derived epithelioid and giant cells with surrounding lymphocytes (kim2024advancesincellular pages 1-5, starshinova2024chronicsarcoidosisdiagnostic pages 14-15).

10.3 Laboratory tests / biomarkers

Supportive biomarkers include: * Serum ACE (produced by monocytes/macrophages/epithelioid cells) reported to correlate with granuloma burden and radiologic stages II–III and may reflect activity/extrathoracic involvement (starshinova2024chronicsarcoidosisdiagnostic pages 15-17, starshinova2024chronicsarcoidosisdiagnostic pages 14-15).
Soluble IL-2 receptor (sIL-2R) as a marker of Th1 activation; may predict progression/relapse (starshinova2024chronicsarcoidosisdiagnostic pages 15-17).
Hypercalcemia with low PTH and normal/low 25-hydroxyvitamin D can occur (starshinova2024chronicsarcoidosisdiagnostic pages 15-17, starshinova2024chronicsarcoidosisdiagnostic pages 14-15).

BAL findings may show lymphocytosis (>15%) and CD4/CD8 ≥3.5 but are not specific (starshinova2024chronicsarcoidosisdiagnostic pages 15-17).

10.4 Imaging

HRCT: preferred over CXR for sensitivity and evaluation of complications (baratella2025ctimagingfeatures pages 3-4, baratella2025ctimagingfeatures pages 1-3).
FDG-PET/CT: a 2025 meta-analysis (search through Sep 2023) reported pooled sensitivity 0.971 and specificity 0.873 for suspected pulmonary sarcoidosis; SUVmax reduction correlated with improved FVC and DLCO and may help guide immunosuppression decisions (doi:10.1007/s00330-024-10949-4) (donnelly2025metaanalysisof[18f]fdgpetct pages 1-2).

10.5 Differential diagnosis

Imaging reviews stress differentiation from tuberculosis, silicosis, malignancy, organizing pneumonia, hypersensitivity pneumonitis, etc., and emphasize integrating clinical/radiologic/pathologic evidence with exclusion of alternatives (baratella2025ctimagingfeatures pages 1-3).

11. Outcome / Prognosis

11.1 Mortality and survival (recent real-world estimates)

A 2024 population-based cohort study (Clalit Health Services; incident cases 2000–2016) reported higher mortality in sarcoidosis than controls (17.7% vs 10.6%), with adjusted all-cause mortality HR 1.79 (95% CI 1.64–1.96) and the highest hazard in the first year post-diagnosis (patt2024elevatedmortalityrisk pages 1-2). Another excerpt reports first-year multivariable HR 2.99 (95% CI 2.39–3.75), and persistent but lower hazards thereafter (patt2024elevatedmortalityrisk pages 8-9). Predictors included age at diagnosis, male sex, and comorbidity burden (patt2024elevatedmortalityrisk pages 1-2, patt2024elevatedmortalityrisk pages 8-9).

11.2 Prognostic functional markers

Imaging-focused reviews highlight functional thresholds associated with progression/response such as ≥5% decline in FVC and ≥10% decline in DLCO, and note that fibrosis extent (e.g., >20% parenchymal fibrosis on CT) correlates with worse outcomes (baratella2025ctimagingfeatures pages 3-4).

12. Treatment

12.1 Current standard pharmacotherapy (guideline-aligned approach)

A practical evidence-based review states oral glucocorticoids remain first-line for symptomatic pulmonary sarcoidosis (typical starting prednisone 20–40 mg/day) with tapering over 6–18 months guided by response; steroid-sparing agents are often required due to toxicity (doi:10.3390/jcm14196828) (dhanani2025immunosuppressivetherapiesin pages 1-3). Second-line agents include methotrexate (preferred), azathioprine, leflunomide, and mycophenolate; refractory disease options include anti-TNF agents (infliximab, adalimumab) and emerging approaches such as JAK inhibitors, rituximab, and repository corticotropin injection (RCI) (dhanani2025immunosuppressivetherapiesin pages 3-4, dhanani2025immunosuppressivetherapiesin pages 10-12).

MAXO suggestions (non-exhaustive): glucocorticoid therapy; methotrexate therapy; TNF inhibitor therapy; antifibrotic therapy; immunosuppressive therapy; JAK inhibitor therapy.

12.2 Recent developments (high-priority evidence)

Methotrexate as first-line alternative (NEJM 2025): In the PREDMETH noninferiority trial (NCT04314193), methotrexate was noninferior to prednisone for 24-week improvement in % predicted FVC (+6.11 vs +6.75 points); adverse event profiles differed (doi:10.1056/NEJMoa2501443) (kahlmann2025firstlinetreatmentof pages 1-2). This is a major development supporting steroid-minimizing strategies.

12.3 Biologics and advanced immunomodulators

Infliximab (anti-TNF): ClinicalTrials.gov record NCT00073437 describes a multicenter Phase 3 randomized, double-blind, placebo-controlled trial (n=139) assessing infliximab (3 or 5 mg/kg) with primary endpoint change in % predicted FVC at week 24, and cites associated publications including PMID 16840744 and PMID 18256069 (NCT00073437 chunk 1).
Adalimumab: NCT00311246 (progressive sarcoidosis; n=11) used adalimumab 40 mg SC weekly; primary endpoint was change in FVC from screening to week 24 (NCT00311246 chunk 2).

12.4 Antifibrotics / progressive fibrotic sarcoidosis trials

Pirfenidone: NCT03260556 is a Phase 4 randomized, triple-masked placebo-controlled trial (estimated n=60) in progressive fibrotic sarcoidosis; primary endpoint “time until clinical worsening” over two years (NCT03260556 chunk 1).
Nintedanib: NCT06479603 is recruiting and compares nintedanib vs standard of care in fibrotic sarcoidosis; the provided chunk includes fibrosis-based inclusion criteria but does not show endpoints/phase/enrollment in that excerpt (NCT06479603 chunk 2).

12.5 Efzofitimod (ATYR1923) — steroid-sparing investigational therapy

NCT03824392 is a completed early study of IV ATYR1923/efzofitimod; registry chunk cites related publications including PMID 37854715 and PMID 36356657 (NCT03824392 chunk 2). (Detailed endpoints/phase are not present in the extracted chunk.)

13. Prevention

No disease-specific primary prevention strategies were identified in the retrieved sources. Prevention in practice centers on (i) avoiding unnecessary immunosuppression in self-limited disease, (ii) monitoring and mitigating treatment complications, and (iii) addressing exposure hypotheses where relevant, but quantitative prevention evidence was not extractable from the provided texts.

14. Other Species / Natural Disease

No naturally occurring veterinary sarcoidosis analogs were identified in the retrieved evidence set.

15. Model Organisms

The PPP/macrophage study reports both in vitro giant cell and in vivo murine granuloma models in which PPP inhibitors attenuated granuloma formation, supporting tractable experimental models for granulomatous inflammation and therapeutic targeting (dhanani2025immunosuppressivetherapiesin pages 10-12). Additional organism-specific model catalogs (MGI/IMPC) were not retrieved in this run.

Expert opinions and authoritative analysis (from high-authority sources)

The JCI 2024 review frames sarcoidosis as a “complex immune-mediated disease characterized by clusters of immune cells called granulomas” and emphasizes insights emerging from high-resolution single-cell/spatial studies (doi:10.1172/jci175264) (weeratunga2024immunemechanismsof pages 1-2).
The immunopathogenesis review emphasizes an IFN-γ/Th1–Th17 axis and dysregulated innate–adaptive crosstalk as central drivers of granuloma persistence and fibrotic progression (doi:10.1055/a-2716-5737) (vagts2025immunopathogenesisofsarcoidosis pages 1-2).
The NEJM 2025 PREDMETH trial provides the strongest recent clinical evidence supporting methotrexate as an initial therapy option with comparable short-term lung function improvement to prednisone (doi:10.1056/NEJMoa2501443) (kahlmann2025firstlinetreatmentof pages 1-2).

Key gaps and limitations of this evidence set

Several requested identifier systems (MeSH, ICD-11, Orphanet, OMIM disease entry) were not present in the retrieved texts and cannot be reliably asserted without dedicated database queries.
Variant-level (ClinVar/ACMG) pathogenic variant curation is not possible from the extracted passages.
Some trial details for efzofitimod Phase 3 (NCT05415137), tofacitinib trials, and the nintedanib record endpoints were not contained in the retrieved chunks; additional ClinicalTrials.gov sections would be required for full endpoint extraction.

References

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(guttmannducke2025firstinsightsand pages 1-2): Claudia Guttmann-Ducke, Martin Lutnik, Maximilian Robert Gysan, Pavla Sarova, Christopher Milacek, Christina Bal, Wolfgang Graninger, Helmut Prosch, Daniela Gompelmann, and Marco Idzko. First insights and future research perspectives from the sarcoidosis registry at the medical university of vienna. Scientific Reports, Mar 2025. URL: https://doi.org/10.1038/s41598-025-93708-9, doi:10.1038/s41598-025-93708-9. This article has 1 citations and is from a peer-reviewed journal.
(guttmannducke2025firstinsightsand pages 2-3): Claudia Guttmann-Ducke, Martin Lutnik, Maximilian Robert Gysan, Pavla Sarova, Christopher Milacek, Christina Bal, Wolfgang Graninger, Helmut Prosch, Daniela Gompelmann, and Marco Idzko. First insights and future research perspectives from the sarcoidosis registry at the medical university of vienna. Scientific Reports, Mar 2025. URL: https://doi.org/10.1038/s41598-025-93708-9, doi:10.1038/s41598-025-93708-9. This article has 1 citations and is from a peer-reviewed journal.
(patt2024elevatedmortalityrisk pages 1-2): Yonatan Shneor Patt, Kassem Sharif, Paula David, Or Hen, Omer Gendelman, Yoav Elizur, Basel Ahmaro, Orly Weinstein, Abdulla Watad, Howard Amital, and Niv Ben-Shabat. Elevated mortality risk in the first year post-diagnosis of sarcoidosis: a comprehensive population-based cohort study. Medicina, 60:1787, Nov 2024. URL: https://doi.org/10.3390/medicina60111787, doi:10.3390/medicina60111787. This article has 3 citations.
(patt2024elevatedmortalityrisk pages 8-9): Yonatan Shneor Patt, Kassem Sharif, Paula David, Or Hen, Omer Gendelman, Yoav Elizur, Basel Ahmaro, Orly Weinstein, Abdulla Watad, Howard Amital, and Niv Ben-Shabat. Elevated mortality risk in the first year post-diagnosis of sarcoidosis: a comprehensive population-based cohort study. Medicina, 60:1787, Nov 2024. URL: https://doi.org/10.3390/medicina60111787, doi:10.3390/medicina60111787. This article has 3 citations.
(patt2024elevatedmortalityrisk pages 9-11): Yonatan Shneor Patt, Kassem Sharif, Paula David, Or Hen, Omer Gendelman, Yoav Elizur, Basel Ahmaro, Orly Weinstein, Abdulla Watad, Howard Amital, and Niv Ben-Shabat. Elevated mortality risk in the first year post-diagnosis of sarcoidosis: a comprehensive population-based cohort study. Medicina, 60:1787, Nov 2024. URL: https://doi.org/10.3390/medicina60111787, doi:10.3390/medicina60111787. This article has 3 citations.
(weeratunga2024immunemechanismsof pages 1-2): Praveen Weeratunga, David R. Moller, and Ling-Pei Ho. Immune mechanisms of granuloma formation in sarcoidosis and tuberculosis. The Journal of Clinical Investigation, Jan 2024. URL: https://doi.org/10.1172/jci175264, doi:10.1172/jci175264. This article has 84 citations.
(dhanani2025immunosuppressivetherapiesin pages 10-12): Zehra Dhanani and Rohit Gupta. Immunosuppressive therapies in pulmonary sarcoidosis: a practical, evidence-based review. Journal of Clinical Medicine, 14:6828, Sep 2025. URL: https://doi.org/10.3390/jcm14196828, doi:10.3390/jcm14196828. This article has 2 citations.
(starshinova2024chronicsarcoidosisdiagnostic pages 26-27): Anna Starshinova, Elizaveta Berg, Artem Rubinstein, Anastasia Kulpina, Igor Kudryavtsev, and Dmitry Kudlay. Chronic sarcoidosis: diagnostic difficulties and search for new criteria of inflammatory activity (a case report and literature review). Journal of Clinical Medicine, 13:6974, Nov 2024. URL: https://doi.org/10.3390/jcm13226974, doi:10.3390/jcm13226974. This article has 5 citations.
(starshinova2024chronicsarcoidosisdiagnostic pages 15-17): Anna Starshinova, Elizaveta Berg, Artem Rubinstein, Anastasia Kulpina, Igor Kudryavtsev, and Dmitry Kudlay. Chronic sarcoidosis: diagnostic difficulties and search for new criteria of inflammatory activity (a case report and literature review). Journal of Clinical Medicine, 13:6974, Nov 2024. URL: https://doi.org/10.3390/jcm13226974, doi:10.3390/jcm13226974. This article has 5 citations.
(baratella2025ctimagingfeatures pages 3-4): Elisa Baratella, Valeria di Luca, Alessandra Oliva, Ilaria Fiorese, Antonio Segalotti, Marina Troian, Stefano Lovadina, Barbara Ruaro, Francesco Salton, Roberta Polverosi, and Maria Assunta Cova. Ct imaging features of pulmonary sarcoidosis: typical and atypical radiological features and their differential diagnosis. Medicina, 61:2094, Nov 2025. URL: https://doi.org/10.3390/medicina61122094, doi:10.3390/medicina61122094. This article has 1 citations.
(baratella2025ctimagingfeatures pages 1-3): Elisa Baratella, Valeria di Luca, Alessandra Oliva, Ilaria Fiorese, Antonio Segalotti, Marina Troian, Stefano Lovadina, Barbara Ruaro, Francesco Salton, Roberta Polverosi, and Maria Assunta Cova. Ct imaging features of pulmonary sarcoidosis: typical and atypical radiological features and their differential diagnosis. Medicina, 61:2094, Nov 2025. URL: https://doi.org/10.3390/medicina61122094, doi:10.3390/medicina61122094. This article has 1 citations.
(dhanani2025immunosuppressivetherapiesin pages 12-13): Zehra Dhanani and Rohit Gupta. Immunosuppressive therapies in pulmonary sarcoidosis: a practical, evidence-based review. Journal of Clinical Medicine, 14:6828, Sep 2025. URL: https://doi.org/10.3390/jcm14196828, doi:10.3390/jcm14196828. This article has 2 citations.
(dhanani2025immunosuppressivetherapiesin pages 3-4): Zehra Dhanani and Rohit Gupta. Immunosuppressive therapies in pulmonary sarcoidosis: a practical, evidence-based review. Journal of Clinical Medicine, 14:6828, Sep 2025. URL: https://doi.org/10.3390/jcm14196828, doi:10.3390/jcm14196828. This article has 2 citations.
(dhanani2025immunosuppressivetherapiesin pages 1-3): Zehra Dhanani and Rohit Gupta. Immunosuppressive therapies in pulmonary sarcoidosis: a practical, evidence-based review. Journal of Clinical Medicine, 14:6828, Sep 2025. URL: https://doi.org/10.3390/jcm14196828, doi:10.3390/jcm14196828. This article has 2 citations.
(kahlmann2025firstlinetreatmentof pages 1-2): Vivienne Kahlmann, Montse Janssen Bonás, Catharina C. Moor, Jan C. Grutters, Rémy L.M. Mostard, Henricus N.A.J. van Rijswijk, Jan van der Maten, Emiel R. Marges, Linda A.A. Moonen, Maria J. Overbeek, Bart Koopman, Daan W. Loth, Esther J. Nossent, Michiel Wagenaar, Henk Kramer, Pascal L.M.L. Wielders, Peter I. Bonta, Stefan Walen, Brigitte A.H.A. Bogaarts, René Kerstens, Mayka Overgaauw, Marcel Veltkamp, and Marlies S. Wijsenbeek. First-line treatment of pulmonary sarcoidosis with prednisone or methotrexate. New England Journal of Medicine, 393:231-242, Jul 2025. URL: https://doi.org/10.1056/nejmoa2501443, doi:10.1056/nejmoa2501443. This article has 53 citations and is from a highest quality peer-reviewed journal.
(NCT00073437 chunk 1): A Study of Infliximab in Patients With Sarcoidosis. Centocor, Inc.. 2003. ClinicalTrials.gov Identifier: NCT00073437
(NCT00311246 chunk 2): Trial of Adalimumab in Progressive Sarcoidosis. University of Chicago. 2006. ClinicalTrials.gov Identifier: NCT00311246
(NCT03824392 chunk 2): Study of Intravenous ATYR1923 (Efzofitimod) for Pulmonary Sarcoidosis. aTyr Pharma, Inc.. 2019. ClinicalTrials.gov Identifier: NCT03824392
(NCT03260556 chunk 1): Robert P Baughman. Pirfenidone for Progressive Fibrotic Sarcoidosis. University of Cincinnati. 2017. ClinicalTrials.gov Identifier: NCT03260556
(NCT06479603 chunk 2): Sahajal Dhooria. RCT of Nintedanib in Fibrotic Sarcoidosis. Post Graduate Institute of Medical Education and Research, Chandigarh. 2024. ClinicalTrials.gov Identifier: NCT06479603
(patt2024elevatedmortalityrisk pages 2-3): Yonatan Shneor Patt, Kassem Sharif, Paula David, Or Hen, Omer Gendelman, Yoav Elizur, Basel Ahmaro, Orly Weinstein, Abdulla Watad, Howard Amital, and Niv Ben-Shabat. Elevated mortality risk in the first year post-diagnosis of sarcoidosis: a comprehensive population-based cohort study. Medicina, 60:1787, Nov 2024. URL: https://doi.org/10.3390/medicina60111787, doi:10.3390/medicina60111787. This article has 3 citations.
(casanova2023examinationofeqtl pages 1-3): Nancy G Casanova, S. Camp, Manuel L Gonzalez-Garay, Ken Batai, Lori Garman, Courtney G Montgomery, Nathan Ellis, Rick A. Kittles, C. Bime, Amy P. Hsu, Steven M. Holland, Yves A. Lussier, J. Karnes, N. Sweiss, Lisa A Maier, L. Koth, David R Moller, N. Kaminski, and Joe G. N. Garcia. Examination of eqtl polymorphisms associated with increased risk of progressive complicated sarcoidosis in european and african descent subjects. European journal of respiratory medicine, 5:359-371, Dec 2023. URL: https://doi.org/10.31488/ejrm.137, doi:10.31488/ejrm.137. This article has 2 citations.

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OpenScientist Report

Inheritance

Subtypes

Mechanistic Hypotheses

Discussions and Knowledge Gaps

Pathophysiology

Pathograph

Phenotypes

Genetic Associations

Medical Actions

Environmental Factors

Biochemical Markers

Source YAML

References & Deep Research

Deep Research

1. Disease Information

1.1 Definition and overview

1.2 Key identifiers (with availability in retrieved sources)

1.3 Synonyms / alternative names

1.4 Evidence provenance

2. Etiology

2.1 Causal factors (current consensus)

2.2 Genetic risk factors (susceptibility/severity loci)

2.3 Environmental and infectious risk factors

2.4 Protective factors

2.5 Gene–environment interactions

3. Phenotypes (clinical manifestations)

3.1 Core clinical phenotype domain

3.2 Example organ involvement frequencies (from retrieved sources)

3.3 Onset and course (high-level)

3.4 Quality of life

3.5 HPO term suggestions (non-exhaustive; mapped to retrieved phenotype domains)

4. Genetic/Molecular Information

4.1 “Causal genes” vs susceptibility genes

4.2 Pathogenic variants (status in retrieved evidence)

4.3 Modifier genes / severity genetics

4.4 Epigenetic information

5. Environmental Information

6. Mechanism / Pathophysiology

6.1 Causal chain (trigger → granuloma → organ dysfunction)

6.2 Key immune pathways and cell types (with ontology suggestions)

6.3 Recent developments (2023–2024 priority): single-cell / spatial / metabolic mechanisms

6.4 Imaging/biopsy advances linked to mechanism

7. Anatomical Structures Affected

7.1 Organ-level involvement

7.2 UBERON suggestions (non-exhaustive)

8. Temporal Development

9. Inheritance and Population

9.1 Epidemiology (incidence, prevalence, demographics)

9.2 Genetic architecture / inheritance

10. Diagnostics

10.1 Diagnostic criteria (core consensus)

10.2 Histopathology

10.3 Laboratory tests / biomarkers

10.4 Imaging

10.5 Differential diagnosis

11. Outcome / Prognosis

11.1 Mortality and survival (recent real-world estimates)

11.2 Prognostic functional markers

12. Treatment

12.1 Current standard pharmacotherapy (guideline-aligned approach)

12.2 Recent developments (high-priority evidence)

12.3 Biologics and advanced immunomodulators

12.4 Antifibrotics / progressive fibrotic sarcoidosis trials

12.5 Efzofitimod (ATYR1923) — steroid-sparing investigational therapy

13. Prevention

14. Other Species / Natural Disease

15. Model Organisms

Expert opinions and authoritative analysis (from high-authority sources)

Key gaps and limitations of this evidence set