Mediastinal teratoma associated with Klinefelter's syndrome

The clinical and autopsy findings in a case of histologically benign teratoma of the mediastinum in a 19-year-old man with Klinefelter's syndrome are presented. A rough statistical analysis based on a review of the literature revealed that the incidence rate of Klinefelter's syndrome among the patients with mediastinal germ cell tumor is 30 to 40 times that of Klinefelter's syndrome among the general control population. The pathogenesis of this neoplasm appears to be related to the genetic abnormality in Klinefelter's syndrome, and this seems to predispose to the development of extragonadal mediastinal germ cell neoplasms.