Abstract
A 14-year-old boy presented with a soft tissue swelling on the outer aspect of his left upper arm. Examination of the tumor by light microscopy showed a small round cell tumor with a rare focus of myogenic differentiation. Myogenic differentiation was confirmed on ultrastructural examination by immunohistochemistry and reverse transcriptase polymerase chain reaction (RT-PCR). Conventional G-banding and fluorescent in situ hybridization (FISH) demonstrated a complex variant of t(21;22)(q22;q12). By RT-PCR, the EWS-ERG fusion transcript was defined as type 9e. This tumor was unusual in that it showed characteristics of myogenic and neural differentiation, and contained a rearrangement of the EWS gene consistent with a diagnosis of Ewing's sarcoma. This supports the hypothesis that a class of biphenotypic childhood sarcomas, with features of myogenic and neural differentiation, exists that may be related to the Ewing's sarcoma family of tumors.
Get full access to this article
View all access options for this article.