Yolk sac tumor and testicular microlithiasis.

Yolk sac tumor (YST) of prepubertal testis is a peculiar neoplasm with overall good prognosis. There are no known conditions associated with the development of this tumor. The case of a 2-year-old boy with testicular YST and presence of testicular microlithiasis (TM) in the adjacent-still-recognizable testicular tissue is reported. Concentrically laminated microliths were clearly extratubular structures. Ultrasound of the remaining testis revealed microlithiasis. Bilateral TM is being recognized with increasing frequency due to the extensive use of ultrasound. The exact meaning of its finding has not been definitively elucidated, but the association of TM with cryptorchidism, intratubular germ cell neoplasia and germ cell tumors either of the testis or mediastinum is on record. The combination of prepubertal YST and bilateral TM has not been reported previously. Finding of TM at this early age suggests a congenital deranged Sertoli cell function and/or an abnormal gonadal embryogenesis in its pathogenesis.