Adding Perplexity to Rarity: Diffuse S100-Protein and SOX10 Expression in a Molecularly Confirmed PAX7-Positive Primary Cutaneous Ewing Sarcoma

Ourania Parra, Ravina Thuraisingam, Michael L. Baker, Darcy A. Kerr, Konstantinos Linos

Research output: Contribution to journalArticlepeer-review

Abstract

ABSTRACT: Primary cutaneous Ewing sarcoma (EWS) is a very rare neoplasm that shares similar morphologic, immunohistochemical, and molecular features with its osseous counterpart. Herein, we present an extraordinarily rare case of PAX7-positive cutaneous EWS in a 9-year-old girl that was also diffusely positive for SOX10 and S100-protein. Next generation sequencing detected the EWSR1-FLI1 fusion supporting the diagnosis, which was further validated by break-apart EWSR1 fluorescence in situ hybridization. Diffuse S100-protein and SOX10 expression has been reported only in a handful of cases of EWS and may pose significant diagnostic challenges for dermatopathologists. PAX7 is a recently introduced marker, which is highly sensitive for EWS and can potentially have discriminatory power in the differential diagnosis of cutaneous undifferentiated round blue cell tumors.

Original languageEnglish (US)
Pages (from-to)984-989
Number of pages6
JournalThe American Journal of dermatopathology
Volume43
Issue number12
DOIs
StatePublished - Dec 1 2021
Externally publishedYes

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Dermatology

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