[Leydig Cell Tumor in a Patient with Contralateral Cryptorchidism: A Rare Association].

Gynecomastia is a frequent sign that may be physiological or caused by various benign or malignant diseases. In rare cases, it may be caused by testicular tumors. We describe a case of progressive gynecomastia at age 20 due to a Leydig cell tumor of the right testicle in a patient with a previous history of left-sided cryptorchidism. The patient underwent orchidectomy and testicular prosthesis placement, with subsequent improvement of gynecomastia and normalization of estrogen. Our case, in addition to demonstrating that gynecomastia may regress if the underlying cause is treated in a timely manner, shows that cryptorchidism may be related with the development of Leydig cell tumors in the same way as it is in other testicular tumors.