Leydig cell hypoplasia causing male pseudohermaphroditism: diagnosis 13 years after prepubertal castration.

An 11-yr-old patient with male pseudohermaphroditism who was castrated at nine days of age and raised thereafter as a female was evaluated to determine the cause of abnormal sexual differentiation. Stimulation with ACTH for 8 h revealed no abnormality in the biosynthesis of cortisol or adrenal androgens. The administration of fluoxymesterone (10 mg, orally, daily) for 5 weeks at age 13 yr led to significant decrements in serum levels of sex steroid-binding globulin and T4-binding globulin to a degree similar to that found in 2 normal men, but no change in the basally elevated levels of FSH and LH. LH bioactivity was normal in the rat Leydig cell bioassay. Skin fibroblasts cultured from a labial skin biopsy revealed normal 5 alpha-reductase activity and normal androgen receptors. Reexamination of the original testis specimens by light microscopy failed to reveal Leydig cells. Furthermore, when immunoperoxidase staining for testosterone was performed on the tissue sections, only 30-35 positive cells/10 high power fields were seen. In contrast, examination of testis sections from 4 male infants who died of other causes revealed 94-836 cells/10 high power fields that stained positively for testosterone. Although hCG stimulation testing to confirm Leydig cell hypoplasia could not be done in this patient because of previous castration, this patient demonstrates that the diagnosis can be made without it by the use of immunohistochemical stains and in vivo and in vitro tests to exclude other disorders of androgen biosynthesis or androgen action.