Adrenocorticotropin production by a mammary carcinoma.

A patient with clinical hypercortisolism and an infiltrating ductal carcinoma of the right mammary gland is presented. Provocative testing of adrenal function demonstrated the pattern of ectopic adrenocorticotropic hormone (ACTH) production. Ultrastructural analysis of the tumor revealed 150-200 nm electron-dense granules that when primarily fixed in OsO4 appeared as membrane-bound, centrally dense cored granules. ACTH was extracted from the tumor tissue and immunocytochemically localized in the tumor cell cytoplasm. A clinically significant level of estrogen receptor protein was present in the tumor tissue (120 fmol/mg protein). This case confirms the ability of mammary carcinoma to produce the ectopic ACTH syndrome.