Bilateral pheochromocytomas.

Bilateral pheochromocytomas most often occur as components of well-described syndromes: multiple endocrine neoplasia types 2a and 2b, von Hippel-Lindau disease and neurofibromatosis. We describe 4 patients with isolated bilateral pheochromocytomas; their tumors arose in the absence of stigmata and family history of the syndromes. The manifestations of these 4 individuals are compared with those of 14 other patients who developed pheochromocytomas in both adrenal glands as part of the syndromes. The 4 patients with the isolated pheochromocytomas manifest more rapidly progressing disease: they were 10-14 yrs of age, distinctly younger than those with the syndrome. Three of the 4 exhibited adrenal medullas that were composed entirely of tumor in contrast to the hyperplasia that usually accompanies other bilateral pheochromocytomas. However, malignant transformation of pheochromocytomas was seen both in a non-syndrome patient and in a patient with Lindau's disease.