Coexistence of three distinct adrenal tumors in the same adrenal gland in a patient with primary aldosteronism and preclinical Cushing's syndrome

A 62-year-old woman was admitted to our hospital because of hypokalemia. Physical examination revealed no signs of excessive adrenocortical steroid production, as are found in Cushing's syndrome. Her plasma renin activity (PRA) was suppressed (0.10ng/ml per h), and her serum aldosterone level was high (30.0ng/dl). PRA was not increased after a renin-releasing test. Her plasma adrenocorticotropic hormone (ACTH) level was low (<5pg/ml), but her serum cortisol level was normal (21.0μg/dl). Administration of 8mg dexamethasone did not suppress her plasma cortisol level. Finally, she was diagnosed with clinical primary aldosteronism associated with preclinical Cushing's syndrome. Magnetic resonance image revealed three sequential nodular masses (each 15mm × 15mm) in the right adrenal gland. A right adrenalectomy was performed by endoscopy. The three removed tumors appeared to have different characteristics. Microscopic examination revealed that the upper and lower tumors were adrenocortical adenomas, and the middle tumor was a black adenoma. Immunohistochemical staining for the enzymes involved in cortisol biosynthesis suggested that the upper tumor secreted aldosterone, whereas either or both of the two other tumors secreted cortisol. Surprisingly, at 33 years of age, she had been diagnosed with Cushing's syndrome, due to a cortisol-producing adrenocortical adenoma, and she had received a left adrenalectomy. Clinically and pathophysiologically, this was a very rare case.