Clinically silent pheochromocytoma presenting as an adrenal incidentaloma: the importance of biochemical evaluation.

Pheochromocytoma is an uncommon catecholamine-secreting tumour that may rarely present without classic adrenergic symptoms. We report a woman in her late 70s with an incidentally detected 5 cm left adrenal mass identified during imaging for unrelated indications. Despite long-standing, well-controlled hypertension and absence of classic catecholamine excess symptoms, biochemical evaluation revealed elevated plasma free metanephrines, confirming pheochromocytoma. A CT scan demonstrated a predominantly cystic adrenal lesion with minimal enhancement; however, elevated unenhanced attenuation values were atypical for a benign adrenal adenoma and warranted biochemical evaluation to exclude a hormonally active adrenal lesion. Minimally invasive surgical management was pursued because untreated pheochromocytoma may result in cardiovascular and perioperative complications even in clinically asymptomatic individuals. Surgical resection achieved biochemical cure. This case highlights the importance of biochemical evaluation of adrenal incidentalomas, particularly in elderly patients without classic adrenergic symptoms.