This adrenal gland removed surgically in a patient with Cushing's syndrome has been sectioned in half to reveal an adenoma. Some remaining atrophic adrenal is seen at the right. The adenoma is composed of yellow firm tissue just like adrenal cortex. This neoplasm is well-circumscribed. Histologically, it is composed of well-differentiated cells resembling cortical fasciculata zone. It is benign.