Testicular juvenile granulosa cell tumor in an infant with X/XY mosaicism clinically diagnosed as true hermaphroditism.

We report a testicular juvenile granulosa cell tumor (T-JGCT) with characteristic clinical and histopathological features. The tumor was present in the left abdominal testis of a 7-month-old infant with a 45,X/46,XY karyotype and ambiguous genitalia. Preoperatively, the infant was diagnosed as having functional testicular and ovarian elements based on elevated levels of serum testosterone and estradiol following human chorionic gonadotropin and human menopausal gonadotropin administration, respectively. Histologically, the left gonad contained a tumorous lesion composed of an admixture of cellular areas and multiple cystic follicles that had some continuity with the adjacent testicular tubules. Some tumor cells showed immunoreactivity for estradiol. The right gonad was a streak gonad containing small irregular nests of sex cord-type cells. No maturing ovarian follicle was present in either gonad. To our knowledge, this is the fifth reported case of T-JGCT with abnormal sex chromosomes, and the first case of T-JGCT confirmed to have not only the morphological but also the functional characteristics of granulosa cells.