Cushing's syndrome: a tripartite entity.

The three distinct etiologies of Cushing's syndrome usually reflect the presence of a neoplasm, most often but not necessarily of the pituitary, and all ultimately result in hypercortisolism. Recent advances in diagnosis and treatment have vastly improved the outlook for many patients. Several therapeutic options are outlined, the success of which depends on accurate identification of the cause of hypercortisolism.