Congenital testicular juvenile granulosa cell tumor in a neonate with X/XY mosaicism.

A congenital sex cord-stromal tumor of the testis with morphologic features of juvenile granulosa cell tumor is reported. The tumor occurred in an abdominal testis of a newborn infant with an X/XY karyotype and ambiguous genitalia and presented as a partially cystic mass associated with ascites. Histologically the tumor was comprised of an admixture of solid, cellular, poorly differentiated lobules mimicking graafian follicles. Residual hypoplastic testicular tissue was present at the periphery. This is the 19th reported case of testicular juvenile granulosa cell tumor and the fourth with an underlying sex chromosome anomaly, further emphasizing the relationship of this uncommon neoplasm to abnormal sexual or gonadal development.