[Clinicopathological study of Ewing's sarcoma and primitive neuroectodermal tumor].

A comparative study concerning the histogenesis of Ewing's sarcoma and its relationship with peripheral primitive neuroectodermal tumor (PNET) was undertaken using histological, immunohistochemical and ultrastructural techniques. The cases studied included 22 Ewing's sarcomas, 17 (ganglio) neuroblastomas, 3 peripheral PNETs, 1 peripheral neuroblastoma, 1 Askin's tumor and a case in which it was difficult to distinguish between Ewing's sarcoma and neuroblastoma. Almost all the cases of Ewing's sarcoma showed neural differentiations. Immunohistochemical study using antibodies for neuron-specific enolase, protein gene product 9.5, Leu 7 and neurofilament (200 kD) was most useful for examining the neural differentiation of these tumors. These results suggest that Ewing's sarcoma is in a broad sense one of such peripheral PNETs as (ganglio) neuroblastoma, peripheral neuroblastoma and Askin's tumor.