Neuron-specific enolase and Leu-7 immunoreactive small round-cell neoplasm. The relationship to Ewing's sarcoma in bone and soft tissue.

The authors present an immunohistochemical analysis of tissue from five cases of morphologically distinctive Ewing's sarcoma in bone and soft tissue. The mean age of the five patients was 16.6 years, with a range of 6-28 years. The tumors existed in chest wall, pelvis, and lower extremities. Two siblings with tumor in bone were clinically diagnosed as having Ewing's sarcoma. All cases had immunoreactivity for neuron-specific enolase (NSE), and four cases revealed positive staining for Leu-7. Neuron-specific enolase is highly specific for neurons and neuroendocrine cells. In addition, immunoreactivity for Leu-7, expressing a natural killer activity, has been demonstrated in peripheral nerve fibers and neuroendocrine cells. The authors suggest that NSE and Leu-7 immunoreactive small round-cell neoplasm is probably a primitive neuroectodermal tumor and should be categorized as Ewing's sarcoma in bone and soft tissue.