Diagnostic Efficacy of Biochemical Studies and MIBG Scan in Pheochromocytoma

Park, Hyungkeun; Kim, Jung Gyun; Hong, Bumsik; Kim, Choung Soo; Park, Taehan; Ahn, Han Jong

Abstract

We evaluated the role of clinical symptoms, biochemical studies and metaiodobenzylguanidine (MIBG) scan in the diagnosis of pheochromocytoma. From August 1991 to June 1997, 42 patients with complaints of hypertension or adrenal mass were evaluated with MIBG scan, 24 hour urinary vanillylmandelic acid (VMA), serum and 24 hour urinary catecholamine and radiologic studies such as CT, MRI or ultrasonography. Initial 9 patients were evaluated with 131 I-MIBG scan and the rest 33 patients with 123 I-MIBG scan. Of 42 patients, histologic diagnosis was obtained in 32 patients including 23 patients with pheochromocytoma or paraganglioma and 9 patients with other adrenal or extra-adrenal tumors. Remaining 10 patients had no evidence of adrenal disease on radiologic studies. Paroxysmal symptoms or hypertension was noted in 14 patients with pheochromocytoma or paraganglioma, while it was also found in 12 out of 19 patients without pheochromocytoma or paraganglioma. Sensitivity, specificity and positive predictive value (PPV) of each diagnostic modality were 60.9%, 92.9% and 93.3% in 24 hour urinary VMA, 61.9%, 75.0%, and 81.3% in 24 hour urinary catecholamine, 82.6%, 94.7%, and 95.0% in MIBG scan, respectively. Sensitivity and specificity were improved to 86.9% and 100% when 24 hour urinary VMA and MIBG scan were combined. In conclusion, MIBG scan was the most useful single screening method for the diagnosis of pheochromocytoma, and combination of MIBG scan and 24 hour urinary VMA would enhance the diagnostic accuracy.