A silent pheochromocytoma with regional metastasis and negative germline testing.

Summary: Pheochromocytomas (PCCs) and paragangliomas (PGLs) are rare neuroendocrine tumors characterized by a universal potential for malignancy regardless of size or biochemical profile. While classic presentations involve paroxysmal hypertension, headaches, palpitations, and diaphoresis, an increasing proportion are detected incidentally through unrelated imaging. These 'silent tumors' often lack catecholamine-related symptoms and demonstrate absent or borderline biochemical abnormalities, signifying a substantial diagnostic challenge. Their indolent clinical profile may obscure malignant potential, leading to delayed intervention and missed opportunities for curative resection. We report a clinically and biochemically silent pheochromocytoma with regional lymph node metastasis, negative germline testing, and high-risk histopathologic features despite small tumor size and long-standing radiographic stability. This case illustrates that radiologic suspicion should prompt timely surgical management with appropriate perioperative blockade even in the absence of unequivocal biochemical confirmation. Lifelong surveillance remains essential with high-risk histology, irrespective of presentation. Learning points: Biochemical silence does not imply benign pathology. Pheochromocytomas without catecholamine excess can still exhibit malignant potential, thereby highlighting the need for comprehensive testing in all cases. Discordant testing requires integrative assessment. Equivocal biochemical results should not preclude further evaluation or empiric preoperative blockade, especially when imaging features or clinical context raises suspicion. Tumor size is an unreliable risk surrogate. Even small adrenal lesions may harbor aggressive histopathology; risk stratification must incorporate pathology and molecular profiling. Genetic testing is indispensable but not definitive. Comprehensive germline testing informs prognosis and surveillance, yet negative results do not eliminate the possibility of malignant behavior. Long-term surveillance remains essential. High-risk features mandate sustained biochemical and imaging follow-up, regardless of tumor size, biochemical phenotype, or genetic background.