Silent mixed ganglioneuroma/pheochromocytoma which produces a vasoactive intestinal polypeptide.

An unusual pheochromocytoma was incidentally discovered in a 48-year-old woman. The patient had a 3-year history of myasthenia gravis. At the time of examination in our hospital, the right adrenal tumor was incidentally discovered by ultrasonography of the abdomen. She had no history of headache, perspiration, palpitation or hypertension. Although blood catecholamine levels were within the normal limits, urinary secretion of catecholamine was elevated. Histologically, the tumor was diagnosed to be mixed ganglioneuroma/pheochromocytoma and histochemically confirmed to produce vasoactive intestinal polypeptide. Such a tumor is quite rare.