"Masked" 21-hydroxylase deficiency of the adrenal presenting with gynecomastia and bilateral testicular masses.

An infertile 27 year old man with precocious puberty is described. He presented in adulthood with unilateral and then bilateral gynecomastia, and subsequently testicular tumors developed. An early diagnosis of congenital adrenal hyperplasia would have avoided unnecessary surgery. Initial detailed metabolic evaluation led to the erroneous diagnosis of 11-hydroxylase deficiency because of the presence of an unusual steroid (21-desoxycortisol) in serum which was falsely reported as an increased 11-desoxycortisol (compound S). The observed low urinary pregnanetriol measurements would have supported this diagnosis. Subsequent specific measurements of 21-desoxycortisol established its presence in the serum and its major metabolite, tetrahydro-21-desoxycortisol, in the urine. The unique features in this case of 21-hydroxylase deficiency alert the physician to its unusual clinical presentation and the pitfalls that may be encountered when evaluating adrenal steroidogenesis.