Endocrine Abstracts

Introduction: Pheochromocytoma and paraganglioma are the cause of secondary hypertension, glucose intolerance, arteriosclerosis and associated with increase of mortality. In addition, 10–17% of them are reported to be malignant. Therefore, diagnosis at the early stage is important.

Methods: We retrospectively analyzed the medical records of Japanese patients who were admitted to our hospital from January 2001 to December 2015. They were confirmed pheochromocytoma or paraganglioma pathologically. We also evaluated the postoperative clinical course. The median follow-up period was 5.5 years (ranged 3 months – 15 years).

Forty-eight patients were identified. Forty-five of 48 (94%) cases were referred as incidentaloma. Our diagnostic protocol included 24-h urine fractionated metanephrines (24 h-UMN), 123I-metaiodobenzylguanidine scintigraphy (MIBG), and clonidine suppression test (CST). The cut-off values of 24 h-UMN were 0.4 mg/day for metanephrine, and 0.9 mg/day for normetanephrine, respectively. 24 h-UMN and MIBG were performed in all cases. CST was conducted in 34 cases.

Results: Seventeen of 34 cases (50%) were positive for all three examinations. Fifteen cases (31%) were negative for 24 h-UMN. Among these cases, MIBG was positive in 12 cases (80%). CST was positive in 11 of 12 cases (92%). Surgical intervention was carried out when either 24 h-UMN or MIBG was positive. Surprisingly, no recurrence was found, during a follow-up period, though two cases had tumors with capsule invasion. We found better prognosis in our cohort contrary to recent reviews. We can propose two explanations. First, the rate of incidental pheochromocytoma or paraganglioma was higher than previous report by Kopetschke et al. who described that it was 59 of 201 (29%). Secondly, our protocol of examination gave us a chance to diagnose incidentaloma as pheochromocytoma or paraganglioma early on.

Conclusion: The combination of 24 h-UMN, MIBG, and CST may enable us to diagnose pheochromocytoma and paraganglioma at the early stage, which may reduce the recurrence and mortality.