Overview
Primary cutaneous/subcutaneous Ewing sarcoma (EFST) are rare tumors arising from cutaneous or subcutaneous tissue without invasion of the underlying aponeurosis 1. They are typically small (<5cm) and can occur in any location, with a predilection for distal, truncal, and head/neck sites 1.Diagnosis
Diagnosis requires a core needle biopsy, following ESMO guidelines for soft-tissue tumors 1.
Pathological and molecular features characteristic of EFST, including EWSR1 rearrangement, must be present 1.
Metastatic disease is rare (<5% at diagnosis) but must be investigated with appropriate imaging due to its poor prognosis 1.Management
Treatment involves neoadjuvant and adjuvant chemotherapy, alongside local treatment 1.
For localized disease, treatment aims for curability while minimizing acute and late toxicity 1.
Small tumors (<200mL) may be treated with less intensive chemotherapy protocols, such as the Saint Jude regimen (low-dose semi-continuous cyclophosphamide/doxorubicin induction, vincristine/actinomycin maintenance), as an alternative to classical VDC/IE regimens 1.
Treatment should occur in specialized centers 1.Key Recommendations
Primary cutaneous/subcutaneous Ewing sarcoma should be treated in specialized centers 1. (Evidence: Expert opinion)
Metastatic disease should be carefully searched for at diagnosis using appropriate imaging, given the poor prognosis associated with metastatic presentation 1. (Evidence: Expert opinion)
For small, localized tumors (<200mL), less intensive chemotherapy protocols may be considered to minimize toxicity while aiming for curability 1. (Evidence: Expert opinion)References
1 Valentin T, Winter S, Martin V, Csanyi M, Marec Berard P, Laurence V et al.. Primary cutaneous/subcutaneous Ewings sarcoma. Bulletin du cancer 2025. link