Coexistence of adrenal Cushing syndrome and pheochromocytoma in a "corticomedullary adenoma" - A case report and review of the literature

Mixed pheochromocytoma and adrenal cortical adenoma (corticomedullary adenoma) is extremely rare. We report a 41-year-old woman diagnosed preoperatively with Cushing syndrome of adrenal origin. Nonsuppressible serum cortisol and 24-hour urine free cortisol levels by a standard tow-dose dexamethasone suppression test with a low plasma adrenocorticotropic hormone (ACTH) level suggested ACTH-independent Cushing syndrome. Magnetic resonance imaging (MRI) revealed a left adrenal mass about 4 cm in diameter, showing a slightly heterogenous signal drop in chemical shift imaging, suggesting high lipid content in the tumor. The T2-weighted image, however, had a mildly high signal, rather than the typical normal to low signal characteristic of a cortical adenoma. I-131-6 beta-iodomethyl-norcholesterol (NP-59) scintigraphy revealed early accumulation of radioactivity in the left suprarenal region, suggesting a functioning cortical tumor. The patient underwent left adrenalectomy, but the surgery caused a marked elevation of systolic blood pressure (greater than 200 mm Hg). The suspicion of pheochromocytoma was entertained. Mixed pheochromocytoma and adrenal cortical adenoma (corticomedullary adenoma) were disclosed by immunohistochemical stains and electron microscopic examination. This case is the fifth reported pathologically proven cortico-medullary adenoma. We include special image findings that contain characteristics of both cortical and medullary components.