Spectrum of pheochromocytoma in the 131 I‐MIBG era

131 I‐metaiodobenzylguanidine ( 131 I‐MIBG) scintigraphy allows for both functional diagnosis and anatomical localization of pheochromocytoma. The spectrum of pheochromocytoma since the routine use of preoperative 131 I‐MIBG scan was studied. From 1980 to 1986, a total of 34 patients were primarily diagnosed and treated at the University of Michigan Medical Center, Ann Arbor, Michigan, U.S.A. There were 16 males and 18 females. The mean age was 38 years and 4 patients (11.8%) were under 18 years of age. Six patients (17.6%) had family history of pheochromocytoma or multiple endocrine neoplasia (MEN) II syndrome. The presenting symptoms were hypertension in 29 patients (85.3%); attacks of headache, palpitation, sweating, and flushing in 4 (11.8%), and 1 patient presented with a neck mass. Plasma catecholamines were elevated in 97% of patients while urinary catecholamines and metabolites were elevated in 93.5%. 131 I‐MIBG was accurate in 82.3%, partly positive in 11.8%, and false‐negative in 5.9% of patients. CT scan was accurate in 80%, partly positive in 10%, but failed to show the tumor in another 10% of patients. At operation, extraadrenal lesions were found in 38.2% of the patients and among these, one‐third were extraabdominal. Multiple tumors occurred in 5 (14.7%), and bilateral adrenal lesions occurred in 4 patients (11.8%). Malignancy was diagnosed in 3 patients (8.8%) after an average follow‐up period of 2 years. We conclude that the use of routine preoperative 131 I‐MIBG scanning improves localization of pheochromocytoma and earlier diagnosis is possible in patients with MEN II syndrome. Multiple tumors, extraadrenal and extraabdominal lesions occur more often than commonly believed. The low rate of confirmed malignancy is probably related to the short period of follow‐up.