Primary pulmonary Ewing's sarcoma: report of a case.

The Ewing's sarcoma family of tumors has been reported to originate in a variety of sites, most commonly in the extremities. We herein describe a rare case of primary pulmonary Ewing's sarcoma in a patient with a family history of sarcoma. The patient was a 42-year-old male, who presented with hemoptysis. Chest radiographs revealed a pulmonary mass in the right lower lobe. Clinical and radiological examinations (computed tomography and positron emission tomography) revealed that the lesion was a primary lesion. The lesion was resected by right lower lobectomy. The tumor was located in the pulmonary parenchyma, and there was no evidence of an extrapulmonary involvement by the tumor. Histologically, the tumor was composed of uniform cells with round nuclei and scant cytoplasm which were arranged in cohesive lobules with rare pseudorosette formation. Immunohistochemically, the tumor cells were positive for CD99, and negative for epithelial markers, neuroendocrine markers, myogenic markers and lymphoma markers. This diagnosis was further supported by the cytogenic and reverse transcriptase-polymerase chain reaction findings of EWS/FLI-1 fusion transcripts. This demonstrated the presence of a very rare primary pulmonary Ewing's sarcoma. The patient was treated with chemotherapy after the operation because Ewing's sarcoma is an aggressive neoplasm. The patient has had no recurrent disease for 6 months after the operation.