Cushing's disease coexisting with a single macronodule simulating adenoma of the adrenal cortex

A rare case of Cushing's disease coexisting with a single macronodule simulating adenoma of the adrenal cortex is presented. The basal and dynamic tests supported the diagnosis of Cushing's disease, whereas the CT-scan, ultrasound and iodocholesterol uptake were suggestive of a left adrenal adenoma. Treatment consisted of extirpation of the nodular gland followed by pituitary irradiation. The examination revealed a single macronodule with no histological membrane, surrounded by hyperplastic adrenocortex. Together with the three similar ones reported in the literature this case suggests that nodular hyperplasia may be an intermediary stage between diffuse hyperplasia and the appearance of an autonomous adenoma after long-term stimulation of the hyperplastic gland.