Non-cushingoid Cushing's syndrome due to adrenocorticotropic hormone-independent bilateral adrenocortical macronodular hyperplasia

This case report describes a 68-year-old man with Cushing's syndrome due to adrenocorticotropic hormone (ACTH)-independent bilateral adrenocortical macronodular hyperplasia (AIMAH). He was referred to our hospital for evaluation of bilateral enlargement of the adrenal glands found incidentally by computed tomography (CT). He had a ten-year history of hypertension. Although he was normokalemic and did not show Cushingoid features, the diagnosis of ACTH-independent Cushing's syndrome was established by endocrinological examinations. His plasma cortisol showed no diurnal rhythm and was unsuppressible by high-dose (8 mg/day) dexamethasone. Plasma ACTH was undetectable and did not respond to corticotropin-releasing hormone. Excised adrenal glands were markedly enlarged (right 28 g and left 64 g). Macroscopic appearance of the glands showed multiple yellowish nodules typical for AIMAH ; microscopic findings were also compatible with AIMAH. The present case indicates that patients with AIMAH sometimes do not show typical Cushingoid features and therefore AIMAH can be found incidentally from ultrasound or CT examination of the abdomen. (Internal Medicine 34 : 446-450, 1995)