First case of synchronous Leydig cell tumor and spermatocytic tumor in the unilateral testis.

Both Leydig cell tumor (LCT), which is a sex cord-stromal tumor, and spermatocytic tumor (ST), which is a germ cell tumor, are rare testicular tumors. Synchronous LCT and ST in the unilateral testis are extremely rare because of their different origins. Herein, we report the case of an 84-year-old male patient with right scrotal swelling due to a testicular tumor. His age was out of the onset peak age of LCT but within ST. To the best of our knowledge, this is the first case with synchronous LCT and ST in the unilateral testis.