Malignant neuroepithelioma (peripheral neuroblastoma). A clinicopathologic study of 15 cases.

A clinicopathologic study of 15 cases of malignant neuroepithelioma (peripheral neuroblastoma) of soft tissues is reported. The patients were chiefly young Japanese adults with a median age of 21 years. The tumors arose mainly in the soft tissues of the lower extremity (seven cases) and the trunk (four cases). Microscopically, there were sheets of closely packed, small round or oval cells, and Homer Wright-type rosettes were seen in all cases, one of which also had Flexner-type rosettes. Immunohistochemical cytoplasmic localization of neuron-specific enolase (NSE) was demonstrated in six of the eight cases, using the peroxidase-antiperoxidase (PAP) method. In no case, however, was there any staining reaction for S-100 protein. Of the 14 patients for whom follow-up information could be obtained, nine died within a period of 2 years and two were alive and well for over 5 years after the initial treatment. Differential diagnosis from other soft-tissue round-cell sarcomas, such as embryonal or alveolar rhabdomyosarcoma, extraskeletal Ewing's sarcoma, and others, are briefly discussed, on a clinicopathologic basis.