Presence of a Gs alpha mutation in an adrenal tumor expressing LH/hCG receptors and clinically associated with Cushing's syndrome.

We describe the case of a patient with Cushing's syndrome due to a functioning adrenal adenoma. There was a pronounced increase in serum and urinary cortisol after administration of human chorionic gonadotropin. Immunocytochemistry revealed positive immunostaining for LH/hCG receptors. Molecular analysis documented the presence of a gsp mutation at codon 201 (CGT to TGT). The existence of this type of hCG-responsive adrenal tumor may help explain the higher prevalence of cortisol-secreting adrenal tumors versus pituitary-dependent disease in pregnant women with Cushing's syndrome as well as some reported cases of remission following delivery.