Adrenal medullary disease in multiple endocrine neoplasia, type 2: pheochromocytoma and its precursors.

Multiple endocrine neoplasia, type 2 (MEN-type 2), designates the syndrome of medullary thyroid carcinoma, pheochromocytoma, and occasional parathyroid hyperplasia. The thyroid carcinoma, which is usually bilateral and multicentric, is preceded by multifocal C-cell hyperplasia. The adrenal gland manifests pheochromocytoma, which is frequently bilateral and multicentric, and may be malignant. To test the hypothesis that diffuse adrenal medullary hyperplasia is a precursor of pheochromocytoma in this syndrome, we studied the adrenal glands of 19 patients who had MEN-type 2. The findings in the adrenal medulla in these 19 patients were: synchronous bilateral pheochromocytoma in 9 (metastatic in 3); asynchronous bilateral pheochromocytoma in 1 (metastatic); unilateral pheochromocytoma with contralateral diffuse and nodular hyperplasia in 2; unilateral pheochromocytoma with contralateral diffuse hyperplasia in 2; unilateral pheochromocytoma in 1; bilateral nodular hyperplasia in 1; bilateral diffuse hyperplasia in 1; and no abnormality in 2. This spectrum of adrenal medullary pathology suggests that diffuse and nodular medullary hyperplasia are precursors of pheochromocytoma in MEN-type 2.