Contributor: Gordon K. Klintworth
A pheochromocytoma is a rare neoplasm of the chromaffin tissue of the adrenal medulla or sympathetic paraganglia (paraganglioma). The tumor arises from cells that secrete catecholamines. Most pheochromocytoma occur sporadically. A minority are familial and the tumor is sometimes part of a hereditary neoplasia syndrome (multiple endocrine neoplasia syndrome type IIA, multiple endocrine neoplasia syndrome type IIB, von Hippel-Lindau disease, neurofibromatosis type I, McCune-Albright syndrome). Some pheochromocytoma are malignant (5-10%) and reliable histological criteria to predict the biological behavior do not exist. The cardinal symptoms reflect the increased secretion of the catecholamines, which may be episodic. Hypertension is an important manifestation and it may be associated with headache, nausea, vomiting, palpitation, apprehension, tremor, pallor or flushing of the face, chest pain, abdominal pain, and paresthesias of the extremities. Pheochromocytoma accounts for <0.1% of cases of hypertension, but is amenable to treatment if diagnosed early. An increased urinary epinephrine is a sensitive test for pheochromocytoma. Other catecholamine producing tumors (chemodectoma, ganglioneuroma) may have similar manifestations. The best test radiologic test for a pheochromocytoma is the MRI, because almost all tumors have a high signal intenstity T2-weighted image.