A rare initial presentation of giant pheochromocytoma: a case report of acute pulmonary embolism complicated by catecholamine-induced cardiomyopathy.

Pheochromocytoma is a rare neuroendocrine tumor characterized by excessive catecholamine secretion, typically presenting with hypertension, headache, palpitations, and sweating. Giant pheochromocytomas (commonly defined as tumors with diameter >4-6cm) are even rarer and may lead to severe cardiovascular complications, including catecholamine-induced cardiomyopathy and thromboembolic events. We report the case of a 76-year-old female who presented with acute pulmonary embolism and heart failure as the initial features of a giant pheochromocytoma, with concurrent deep vein thrombosis and catecholamine- induced cardiomyopathy. Laboratory tests revealed markedly elevated catecholamine metabolites, while imaging confirmed a right adrenal mass measuring 11.1×7.9 cm, along with bilateral pulmonary artery emboli and left lower extremity deep vein thrombosis. After multidisciplinary evaluation, the patient was managed with α- and β-blockers, anticoagulation, and subsequent surgical resection of the tumor. Postoperative follow-up showed significant improvement in cardiac function and complete resolution of thrombotic events. This case demonstrates the importance of including pheochromocytoma in the differential diagnosis of patients with unexplained thromboembolism or cardiovascular collapse, particularly when an adrenal mass is identified on imaging. Early diagnosis, multidisciplinary management, and timely intervention are crucial for favorable outcomes in such complex and life-threatening presentations.