Juvenile granulosa cell tumor of the infant testis: case report with ultrastructural observations.

This report describes the light-microscopic and ultrastructural features of a juvenile granulosa cell tumor of infant testis. Microscopic examination revealed a macrofollicular patterns simulating the preovulatory Graafian follicle and the juvenile granulosa cell tumor of the ovary. Ultrastructure confirmed three cell types: granulosa, theca interna, and externa, with occasional luteinized cells lacking crystalloids of Reinke. Charcot-Bottcher crystalloids were not detected, though rare cells contained a complex arrangement of filaments. An ultrastructural comparison was carried out with infant testes (2 cases), preovulatory Graafian follicle (1 case), juvenile granulosa cell tumor of ovary, adult granulosa cell tumor of ovary, and adult Sertoli cell tumor of testis and ovary. Ultrastructural similarities were noted between the present case and primitive Sertoli cells, preovulatory granulosa cells, and juvenile granulosa cell tumor of ovary. This may reflect the common histogenesis of Sertoli/granulosa cells from the common specialized gonadal stroma.