| Domain | Key finding | Value / summary | Best supporting citation IDs |
|---|---|---|---|
| Ontology identifier | MONDO ID | MONDO:0017387 (epithelioid sarcoma) | (pqac-00000000) |
| Disease category | Classification | Ultra-rare malignant soft-tissue sarcoma; <1% of all soft-tissue sarcomas; classic/distal and proximal subtypes recognized | (pqac-00000003, pqac-00000004) |
| Rarity / prevalence | Prevalence | <2 per 100,000 | (pqac-00000004, pqac-00000055) |
| Incidence | Population incidence | ~0.03–0.05 per 100,000 overall; alternatively reported as <0.2 and <0.5 new cases per million/year in EU and US, respectively | (pqac-00000004, pqac-00000003, pqac-00000071) |
| Age distribution | Typical age | Mostly adolescents/young adults in classic descriptions; registry mean age ~46 years with peak in 5th decade in recent consensus | (pqac-00000001, pqac-00000004, pqac-00000055) |
| Sex distribution | Male predominance | Male:female ratio ~1.6 overall; some series report up to 2:1 in distal/classic disease | (pqac-00000055, pqac-00000006) |
| Recurrence | Local recurrence / recurrence risk | 5-year risk of recurrence up to 70%; recurrence rate 63.4% in one large review/SEER-derived summary | (pqac-00000058, pqac-00000053) |
| Nodal metastasis | Regional lymph node involvement | >20% overall in reviews; ~30% in a 2023 review; 12.4% in SEER head/neck/extremity STS analysis; 18% in pediatric/young adult NRSTS cohort | (pqac-00000058, pqac-00000071, pqac-00000053) |
| Distant metastasis | Hematogenous metastasis | >40% in 2023 review; historical reviews cite 30–75% by 5 years; common sites include lung and liver | (pqac-00000071, pqac-00000053, pqac-00000058) |
| Survival | Overall prognosis | 5-year relative survival ~50%; 5-year disease-specific survival 55.7% in SEER-derived review; reported 5-year OS ranges ~25–70%; 10-year OS ~60.4% in one review | (pqac-00000055, pqac-00000053) |
| Prognostic factors | Worse outcome associated with | Proximal subtype, tumor >5 cm, multifocality, nodal involvement, vascular invasion, necrosis, high mitotic index/grade, deep axial location, older age, distant metastasis | (pqac-00000058, pqac-00000053, pqac-00000054) |
| Hallmark molecular biomarker | SMARCB1 / INI1 loss | Loss of nuclear INI1/SMARCB1 in >90% of cases; biallelic SMARCB1 inactivation drives ~95% of cases in recent consensus | (pqac-00000004, pqac-00000008, pqac-00000060) |
| Core IHC profile | Positive markers | Cytokeratins, EMA, vimentin; CD34 positive in >50% / about half; ERG positive in ~50% (mostly distal type) | (pqac-00000012, pqac-00000010, pqac-00000011, pqac-00000040) |
| Core IHC profile | Typically negative markers | S-100 and CD31 typically negative; desmin/factor VIII usually negative in differential workup | (pqac-00000011, pqac-00000010) |


*Table: This table condenses high-yield identifiers, epidemiology, prognosis, and hallmark diagnostic biomarkers for epithelioid sarcoma. It is useful as a quick-reference summary for knowledge base curation and evidence-backed clinical context.*