Primary embryonal-choriocarcinoma of the mediastinum in a woman. A case report with immunohistochemical study.

Primary malignant germ cell tumors of the mediastinum are extremely rare among females. This report describes such a tumor arising in the mediastinum of a 26-year-old woman and correlates immunohistochemical studies of the neoplasm with serum tumor markers. Microscopic examination of the tumor revealed an embryonal carcinoma with choriocarcinoma, the latter consisting of sheets of polygonal cells intimately related to multinucleate giant cells that contained beta-human chorionic gonadotropin (beta-HCG) when stained immunohistochemically. The serum beta-HCG level at the time of diagnosis was 8,300 mU/ml and remained elevated throughout the patient's course. Alpha-fetoprotein was not detected in serum or tissue. Postoperative chemotherapy failed to control the growth of the tumor, and the patient died as a result of massive intrathoracic tumor involvement. At autopsy, metastases were found in two periaortic lymph nodes and in the liver. There was no gross or microscopic evidence of ovarian disease. This case illustrates the typical behavior of malignant germ cell tumors of the mediastinum, rare among females and infrequently described in the literature. To our knowledge, this is the first detailed immunohistochemical study of a mediastinal germ cell tumor in a female.