Extraskeletal Ewing's sarcoma (EES) is a rare soft tissue tumor morphologically indistinguishable from the more common Ewing's sarcoma of bone. We report a case of EES arising in the hard palate of 34-yr-old male patient. Microscopically, the monotonous small round cells without neuronal differentiation showed membranous positive immunoreactivity for MIC2/CD99 and vimentin. Ultrastructurally, the tumor cells showed a few intracytoplasmic organelles without evidence of neurosecretory granules or neurofilaments. The EWS-FLI1 chimeric gene was identified using the nested reverse transcriptase-polymerase chain reaction.
Adult ; Antigens, CD/analysis ; Cell Adhesion Molecules/analysis ; Humans ; Immunohistochemistry ; Male ; Oncogene Proteins, Fusion/genetics ; Palatal Neoplasms/genetics/metabolism/*pathology ; Palate, Hard/metabolism/*pathology ; Proto-Oncogene Protein c-fli-1/genetics ; Reverse Transcriptase Polymerase Chain Reaction ; Sarcoma, Ewing's/genetics/metabolism/*pathology ; Transcription, Genetic ; Vimentin/analysis