This adrenal gland, removed surgically from a patient with Cushing syndrome, has been sectioned in half to reveal a cortical 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 the normal cortical fasciculata zone. It is benign.