Familial pheochromocytoma and islet cell tumor of the pancreas.

The occurrence of pheochromocytoma(s) or pancreatic islet cell tumor(s), or both, in two or more members of three unrelated families in a manner consistent with autosomal dominant inheritance suggests that this tumor association is a genetically determined syndrome. Among 11 affected patients (aged five to 53 years), 10 had pheochromocytoma (bilateral in six), four had islet cell tumor (multicentric in one), and three had both tumors. Clinical presentation was due to pheochromocytoma in 10 cases (symptoms or signs commencing before age 10 years in three patients) and islet cell carcinoma in one case. Four patients are dead as a result of the tumors--two from pheochromocytoma and two from islet cell carcinoma.