Mediastinal mixed germ cell tumor in an infertile male with Klinefelter syndrome:A case report and literature review.

Klinefelter syndrome (KS) is a well-documented abnormality of the sex chromosome, with an incidence of 1 in 600 newborn males. It is characterized by a 47, XXY or a mosaic karyotype, hypergonadotrophic hypogonadism, infertility, reduced body hair, gynecomastia, and tall stature. Different neoplasms such as breast, testicular, and lymphoreticular malignancies may occur in 1% to 2% of the cases with KS. Herein we describe a case of mediastinal mixed germ cell tumor (GCT) in a 40-year-old male with KS. Interestingly, this case also had mitral valve prolapse, and an incidental papillary microcarcinoma of the thyroid gland. In view of the presence of pulmonary nodules, antemortem differential diagnoses considered were mycobacterial infection, lymphoma, thymic carcinoma, and a primary/metastatic neoplasm of the lung. As GCT was not considered, the serum markers of a GCT were not performed. The diagnosis of this rare mediastinal mixed GCT with KS was made at autopsy.