Cryptorchidism in the Prader-Willi syndrome.

Among 30 male children seen for the Praer-Willi syndrome 21 had at least 1 undescended testis (70 per cent). In 14 of the 30 patients both testes were undescended (45 per cent). Of 18 patients observed for a period 4 (22 per cent) had late spontaneous descent of 6 testes. Gonadotropin treatment facilitated descent in 3 of 4 patients. Testicular biopsy showed a Sertoli-cell-only appearance in 4 patients. The usual indications for orchiopexy of undescended testes may need to be modified in patients with the Prader-Willi syndrome.