Pheochromocytoma characteristics and behavior differ depending on method of discovery

Context: Modern pheochromocytomas (PHEOs) are often discovered by incidental finding on cross-sectional imaging or mutation-based genetic case detection testing. Little is known about how these PHEOs behave. Objective: To describe the characteristics and behavior of PHEOs discovered incidentally on imaging or through mutation-based genetic case detection testing. Design: Retrospective study. Setting: Referral center. Patients: Consecutive patients with pathology-confirmed PHEOs, treated from 2005 to 2016. Main Outcome Measure(s): Tumor size, plasma/urine fractionated metanephrines and catecholamines, and preoperative management. Results: Two hundred seventy-one patients (52% women, median age 52.0 years) presented with 296 PHEOs. Discovery method was most often incidental finding on cross-section imaging (61%) rather than PHEO-related symptoms (27%) or mutation-based case detection testing (12%). Patients with incidentally discovered PHEOs were older than symptomatic and mutation-based case detection testing patients (median age 56.6 vs 43 vs 35 years, P, 0.0001). Mutation-based case detection PHEOs were smaller than those discovered dueto symptoms (median size 29.0 vs 50.5 mm, P =0.0027). Patients with PHEOs discovered due to symptoms had the highest median concentration of 24-hour urinary metanephrines and total plasma metanephrines (P, 0.0001). These patients required a higher cumulative phenoxybenzamine dose than patients with incidental or case detection PHEO (median 450 vs 375 vs 270 mg, P = 0.029). Conclusions: PHEOs are primarily discovered due to incidental finding on cross-sectional imaging rather than PHEO-related symptoms. PHEOs discovered through mutation-based genetic case detection testing were smaller and required less α-adrenergic blockade preoperatively compared with PHEOs found due to symptoms, which supports routine case detection testing for patients genetically predisposed for PHEOs.