Silent Pheochromocytoma Is an Underrecognized Clinical Entity: Results From a High-Volume Adrenal Surgery Hospital

OBJECTIVE: To characterize the clinical, biochemical, radiological, and pathological features of sporadic silent pheochromocytoma (SPheo), a subtype lacking classic symptoms and presenting with normal or mildly elevated biochemical indices, to enhance diagnostic accuracy. METHODS: A retrospective analysis was conducted of 1273 adrenalectomies performed at a high-volume adrenal surgery hospital from January 2022 to November 2024. Of 103 patients with confirmed pheochromocytoma, 94 had sporadic disease; 14 (14.9%) met SPheo criteria (absence of classic symptoms and biochemical indices <2-fold change compared to the upper reference limit). Tumor size, biochemical profiles (plasma and urine metanephrines), radiological interpretations, and preoperative diagnoses were evaluated. RESULTS: SPheo tumors were smaller (2.9 ± 1.2 cm vs 4.5 ± 1.9 cm, P < .01) and had lower biochemical indices (1.22 ± 0.60-fold vs 11.32 ± 15.42-fold, P < .0001) than overt pheochromocytoma. Plasma and urine metanephrine levels were significantly lower in SPheo (P < .0001 and P < .002, respectively). Preoperative imaging at outside institutions was interpreted as adenoma (n = 6), indeterminate (n = 7), or metastasis (n = 1). At referral, 6 (42.8%) SPheo patients were diagnosed with mild autonomous cortisol secretion. CONCLUSION: SPheo, comprising 14.9% of pheochromocytomas at a high-volume center, is often misdiagnosed due to atypical presentation. Comprehensive biochemical and imaging evaluations, coupled with a high index of suspicion, are critical for accurate diagnosis and timely surgical intervention.