Benign hematologic neoplasm associated with mediastinal mature teratoma in a patient with Klinefelter's syndrome: a case report.

An 18-year-old male with Klinefelter's syndrome presented with a mature teratoma of the mediastinum. He was treated with debulking surgery and brief cisplatin-based chemotherapy. Ten years later, he presented with paraplegia and was found to have an isolated epidural mass. The mass was composed of mature histiocytoid cells reminiscent of those seen in malignant histiocytosis. There was no evidence of medullary dissemination and there was no evidence of recurrence of the germ cell tumor. He received local radiation therapy and a single course of leukemic induction. He remains well 4 years later. This case represents a localized variant of the diffuse histiocytic malignancies associated with malignant mediastinal germ cell tumors.