Pheochromocytoma Characteristics and Behavior Differ Depending on Method of Discovery

Presentation Number: SUN 392
Date of Presentation: April 2nd, 2017

Lucinda M Gruber*1, Irina Bancos2 and William F. Young Jr.2
1Mayo Clinic School of Graduate Medical Education, Rochester, MN, 2Mayo Clinic, Rochester, MN

Abstract

Introduction: Pheochromocytomas (PHEO) were traditionally discovered due to symptoms from catecholamine hypersecretion. However, more recently, PHEO are also found incidentally on cross-sectional imaging or through genetic case detection testing. Little information exists about how PHEO characteristics differ depending on how they are discovered. We sought to determine the differences of PHEO characteristics and behavior in relation to the method of PHEO discovery.

Design: This is a retrospective study of all patients who had adrenalectomy or confirmed pathology for PHEO at Mayo Clinic, Rochester, MN from 2005 through 2014. Data were collected from electronic medical records. Plasma and urine biochemistry values were standardized using standard scores (SS). (SS = [(measured value) – (maximum normal value)] / (maximum normal value)]).

Results: We identified 222 patients (51% women, median age of diagnosis 51.1 yrs (range, 5-84)) who presented with 239 PHEOs. PHEOs were most commonly discovered by incidental finding on cross-sectional imaging (144, 60.3%), followed by symptoms (67, 28.0%), and genetic case detection testing (28, 11.8%). Genetic testing was performed in 81 (36.5%) of our cohort, and 46 (20.7%) had genetic susceptibility to develop PHEO. Bilateral PHEOs were identified in 17 (7.7%) patients, with only one having asynchronous disease. Bilateral disease was more common in patients with a genetic syndrome (P<.0001), and, when compared to unilateral PHEO, was diagnosed at a younger age (median age 36.6 vs. 54.9 yrs, P<.0001).The median tumor size was 41.5 mm (range, 8-260). PHEO discovered due to symptoms were larger than PHEO discovered incidentally or by genetic case detection testing (53.2 vs. 47.2 vs. 35.6 mm; P=.04). Similarly, PHEO discovered based on symptoms had higher median total plasma metanephrines SS (14.8 vs. 5.6 vs. 3.5; P=.03) and median total urine metanephrine SS (77 vs. 5.6 vs. 0.9; P=.0007). Larger tumors required more alpha-adrenergic blockade prior to surgery, both with cumulative and average dose (P=.0031, P=.0009) and were more commonly removed with open surgery rather than laparoscopic approach (P<.0001). Patients discovered due to symptoms vs. incidentally vs. by genetic case detection required higher cumulative (430 vs.370 vs. 220 mg, P=.02), daily average (35 vs 30 vs 21 mg, p=0.001) and daily maximum (48 vs 43 vs 40 mg, P=.02) phenoxybenzamine dose.

 Conclusion: Since 2005, 60% of PHEOs were diagnosed by incidental finding on cross-sectional imaging. PHEOs discovered due to symptoms of catecholamine hypersecretion were larger, more biochemically active, and required a higher dose of phenoxybenzamine prior to surgery than those identified by cross-sectional imaging or genetic case detection testing.

 

Disclosure: WFY Jr.: Ad Hoc Consultant, Nihon Medi-Physics, Ad Hoc Consultant, GlaxoSmithKline. Nothing to Disclose: LMG, IB