Cushing's Syndrome due to Bilateral Adrenocortical Adenomas with Different Pathological Features

A 48-year-old woman with Cushing's syndrome due to bilateral adrenocortical adenomas is reported. The patient presented with a typical Cushingoid appearance. The serum cortisol level was elevated with loss of the diurnal rhythm and the plasma adrenocorticotropic hormone (ACTH) level was undetectable. Dynamic testing showed no suppression of urinary 17-OHCS by high-dose dexamethasone and no stimulation by metyrapone. An abdominal computed tomography (CT) scan showed bilateral adrenal tumors. Bilateral adrenalectomy was performed. The right adrenal gland contained a tumor that was encapsulated and consisted mainly of compact cells. The surrounding cortex was atrophic. The left adrenal gland contained an encapsulated tumor composed predominantly of clear cells. There were numerous small adrenocortical nodules in the surrounding cortex. Immunohistochemical analysis of steroidogenic enzymes (P450scc, 3β-HSD, P450c21, P450c17 and P450c11) was performed. Immunoreactivity of all the enzymes was intense in the compact cells of the right adrenocortical adenoma, while the adjacent non-neoplastic cortex was negative for the enzymes. In the left adrenal tumor, the immunoreactivity of 3β-HSD was intense, while that of P450c17 was weak. In the adrenocortical nodules, 3β-HSD activity was sporadically observed. G protein genes encoding Gs α and Gi2 were examined for activating mutations at codons 201 and 227 (Gs a) and codons 179 and 205 (Gi2 α) in the bilateral adrenal tumors, but no mutations were found. The bilateral adenomas of this patient showed marked differences in microscopic and immunohistochemical studies, suggesting that the capacity of steroidogenesis differs between the right and left tumors.