Extraskeletal Ewing's sarcoma: a clinical, morphological and ultrastructural analysis of five cases with a review of the literature.

In 1969 it was recognised that tumors with light microscopic appearances indistinguishable from Ewing's sarcoma of bone may arise in extraskeletal sites (extraskeletal Ewing's sarcoma). Here, we review the available literature and report five new cases. All five received combined modality therapy with combination chemotherapy and radiotherapy to the primary site followed by surgical excision in two. All attained complete remission; after a median follow-up of 26 months, three remain disease-free but two have relapsed and died. Our experience, in accord with previous series, suggests that extraskeletal Ewing's sarcoma compared with its bony counterpart tends to occur in older subjects, has a similar incidence in males and females, usually presents with a painless mass and readily responds to combined modality therapy. We detected no light or electron microscopic features to denote a histogenetic origin. However, we suspect extraskeletal Ewing's sarcoma may occur more frequently than previously supposed.