LEYDIG CELL TUMOR PRESENTING AS CONGENITAL ADRENAL HYPERPLASIA (CAH)

Abstract

Sexual precocity and a testicular mass can result from a Leydig cell tumor or from simple virilizing CAH with adrenal rests in the testes. These diagnoses are usually distinguished by very high plasma 17-hydroxyprogesterone (170HP) in CAH. However, 170HP from adrenal rests may not be suppressible with glucocorticoids, and these entities may not be distinguishable pathologically. A 3 6/12 y.o. boy had a 2-3 month history of rapid growth and phallic enlargement. The left testis was 1.0 cm and the right was about 1.7 cm long, obscured by a hydrocele. Bone age was 7 yr, testosterone (T) 498 ng/dl, and 170HP 3340 ng/dl, suggesting CAH. Glucocorticoid treatment failed to suppress 170HP and T, and virilization progressed. At 3 9/12 y.o. the 170HP was 7409, the T was 548, and the right testis had grown to about 2.7 cm. An LRF test was prepubertal and an ACTH test showed no significant rise in the elevated basal 170HP, androstenedione or 21-deoxycortisol. Ultrasonography and magnetic resonance scanning revealed a mass replacing the right testis, shown at surgery to be a 2.0 cm Leydig cell tumor. The tumor contained mRNA for P450sec (the cholesterol side-chain cleavage enzyme) and P450c17 (17 α-hydroxylase/17, 20 lyase), but no detectable mRNA for P450c21 (21-hydroxylase), as is typical of testicular tissue but not adrenal tissue. The post-op 170HP and T were normal before and after ACTH. This case illustrates that Leydig cell tumors and non-suppressible adrenal rests in CAH may be hormonally indistinguishable preoperatively.