Metastatic epithelioid trophoblastic tumor in a male patient with mixed germ-cell tumor of the testis.

This report describes a rare case of a concurrent epithelioid trophoblastic tumor (ETT) and a teratoma in a para-aortic lymph node from a 39-year-old male patient with the initial diagnosis of testicular malignant mixed germ-cell tumor. The metastatic lesion was excised 2 years after orchiectomy and chemotherapy. Microscopically, the metastatic lesion contained a teratoma component and dispersed small nests of cohesive chorionic-type intermediate trophoblastic cells, closely resembling gestational ETT in female patients. The diagnosis of ETT in this case was confirmed by stepwise immunohistochemistry. Demonstration of ETT as one of the histologic manifestations of recurrent testicular germ-cell tumors should encourage pathologists to recognize this unique feature in assessing posttreatment mixed germ-cell neoplasm. Furthermore, this case represents a unique opportunity to understand the pathobiology of trophoblastic neoplasms arising from germ-cell tumors.