Ewing sarcoma with extensive neural differentiation: a clinicopathologic, immunohistochemical, and molecular analysis of three cases.

OBJECTIVES Three patients with Ewing sarcomas showing extensive neural differentiation are presented. METHODS The patients were two women and one man between the ages of 15 and 35 years. Anatomically, one tumor was in the lung, one in the testis, and one in the cervix uteri. The symptoms were determined by the location of the neoplasm and included respiratory symptoms, testicular pain, and pelvic manifestations, respectively. Complete surgical resection of the tumors was performed. RESULTS Histologically, all neoplasms showed similar characteristics-namely, a neoplastic cellular proliferation arranged in sheets and composed of small blue cells with round to oval nuclei and inconspicuous nucleoli typical for Ewing sarcoma. In addition, in two cases, there were areas characterized by the presence of neuropil, ganglion cells, and small cells most compatible with ganglioneuroblastoma, while in one tumor, the neural component was characterized by the presence of small cells with prominent perivascular pseudorosettes more closely resembling ependymoma. Immunohistochemical studies in all cases and molecular analysis in two tumors were in keeping with a diagnosis of Ewing sarcoma. CONCLUSIONS The recognition of such histologic variants is important in the diagnostic assessment of these tumors to avoid misinterpretation, especially in small biopsy specimens.