Background: Pigmented or "black" cortical adenoma is a rare variant of the compact or eosinophilic cell type of adrenal gland cortical adenoma. Usually it is non functioning so representing an incidental finding at autopsy, but rare cases producing Cushing's syndrome or hyperaldosteronism have been reported. The simultaneous occurrence of a cortical adenoma and pheochromocytoma in the ipsilateral adrenal gland is an extremely rare event, which has been so far described only seven times with the cortical adenoma always being of the usual yellow or clear cell type. So far no case of "black adenoma" associated with a proliferative condition of the ipsilateral adrenal medulla has ben described.
Case report: A case of functioning pigmented ("black") cortical adenoma in a male patient affected by Cushing's syndrome associated with asymptomatic medullary nodular hyperplasia in the ipsilateral adrenal gland is described. The results of light microscopy, histochemistry, immunohistochemistry, and electron microscopy studies are presented. It is worthy of note the finding of two types of pigment granules (lipofuscin type, neuromelanin type) observed at elecatron microscopy.
Conclusions: The authors underline the difficulty of classifying adrenal medullary nodules and the arbitrarity usually adopted in separating nodular adrenal medullary hyperplasia from early neoplasia (pheochromocytoma). Thus nodular medullary hyperplasia in this case could also be interpreted as an early neoplastic condition. The case herein presented is the first report of a combined cortico-medullary proliferative process in which a "black" adenoma is involved.