Extraskeletal Ewing sarcoma in a 77-year-old woman

Extraskeletal Ewing sarcoma (EES) is a rare soft tissue tumor that is morph ologically indistinguishable from Ewing sarcoma of bone. it is usually foun d in young people, but several cases have occurred in patients older than 5 0 years. The differential diagnoses include other small, blue round cell tu mors (SBRCTs) and other members of the Ewing family of tumors such as the p rimitive neuroectodermal tumor. We present a case of EES in the left inguin al region of a 77-year-old woman. The tumor was distinguished from other SB RCTs by lack of immunoreactivity for epithelial, lymphoid, vascular, neuroe ndocrine, neural, histiocytic, and muscle markers. Primitive neuroectoderma l tumor was excluded because of the lack of neural differentiation by histo logic analysis, immunohistochemistry, and electron microscopy. Extraskeleta l Ewing sarcoma was confirmed by characteristic features on histologic anal ysis, histochemistry, immunohistochemistry, and electron microscopy and by the presence of the t(11;22)(q24;q12) fusion transcript detected by reverse transcriptase-polymerase chain reaction. This case serves to remind the re ader that EES is not a tumor that occurs exclusively in young patients.