A series of 80 consecutive pheochromocytoma patients operated on from 1956 to 1985 were investigated for other neuroectodermal abnormalities. Such abnormalities were found in 23 (29%) patients. Medullary thyroid carcinoma was the most common associated neuroectodermal abnormality followed by von Recklinghausen's neurofibromatosis. Other abnormalities were intracranial tumors, midgut carcinoid, and parathyroid hyperplasia. All 6 patients with multiple pheochromocytomas had other neuroectodermal abnormalities. In the total series, the 14 patients with hereditary disease had multiple neuroectodermal abnormalities (MNA). Hypertension occurred significantly less often in MNA patients (p
