The unique association of malignant histiocytosis and a primary gonadal germ cell tumor.

Previous reports of the association between hematologic malignancies and germ cell tumors have been limited to patients with nonseminomatous tumors, exclusively of mediastinal origin. Among the various hematologic disorders, a large proportion have involved histiocytic tumors, either acute monocytic leukemia or malignant histiocytosis. We now report the first case of simultaneously occurring malignant histiocytosis and testicular embryonal carcinoma. The patient, an 18-year-old male, presented with hepatosplenomegaly due to malignant histiocytosis and was found on further evaluation to have a stage I testicular cancer consisting of teratocarcinoma with endodermal sinus elements. Despite aggressive chemotherapy, the patient died of malignant histiocytosis 6 months after the original diagnosis. The autopsy revealed widespread organ involvement with malignant histiocytosis and no evidence of residual germ cell tumor. This case demonstrates that germ cell tumors associated with hematologic malignancy do not arise solely in extragonadal sites.