Epithelioid sarcoma. A clinicopathologic and electron microscopic study.

This clinicopathologic study concerns four cases of epithelioid sarcoma, which were seen among a group of 603 cases of soft tissue sarcomas in our file. The patients were of young age between 8 and 21 years at the time of initial treatment. The tumors arose in the upper (2 cases) or lower extremities (2 cases), and consisted histologically of irregular nodular masses of Polygonal epithelioid cells merging with spindle cells. Electron microscopy in two cases revealed that the tumor cells were an admixture of synovioblast-like cells and fibroblast-like cells, the former cells being characterized by pseudoacini and filopodia. In three of the four patients, the tumors recurred one to three times, and one patient with primary tumor had metastases to the skin of the more proximal portions of the same extremity and to the regional lymph nodes. Follow-up ranging from two to four years, however, revealed that all patients were living and well after single or multiple operations.