Bilateral adrenal medullary hyperplasia in multiple endocrine neoplasia, type 2: the precursor of bilateral pheochromocytoma.

An asymptomatic 12-year-old girl with multiple endocrine neoplasia, type 2, had high urinary levels of vanillylmandelic acid that suggested pheochromocytoma; she also had bilateral medullary thyroid carcinoma and hyperparathyroidism. Her mother and maternal aunt and uncle had bilateral pheochromocytoma (metastatic in the former two). Bilateral adrenalectomy was performed. Diffuse, non-nodular adrenal medullary hyperplasia was present. This hyperplasia was characterized by increased medullary mitotic activity, decreased corticomedullary ratio, increased total adrenal weight, and increased total catecholamine content (left adrenal). The results in this case suggest that diffuse hyperplasia of the adrenal medulla may be the precursor of pheochromocytoma in patients with this syndrome.