Pheochromocytoma of the pancreas: A report of three cases and a literature review.

Pheochromocytoma is primarily derived from the adrenal medulla. The majority of extra-adrenal pheochromocytoma cases occur in the superior para-aortic region and para-adrenal area. However, pheochromocytoma originating from the pancreas is rare. The present study reports the cases of three patients who had no history of hypertension but were post-operatively diagnosed with pheochromocytoma located in the pancreas. Of the three patients, two were admitted to hospital due to abdominal pain, and imaging examinations revealed a soft-tissue lesion in the head of pancreas. Local resection of the pancreatic tumor was successfully performed and a diagnosis of pheochromocytoma derived from the pancreas was subsequently made by pathologists. The third patient was admitted to hospital for surgical treatment due to the identification of a continuously growing lesion in the tail of pancreas during physical examinations. Distal resection of the pancreas was stopped during surgery when the patient's blood pressure and heart rate suddenly increased to 180/110 mmHg and 140 beats/min, respectively. Due to a marked rise in noradrenaline and adrenaline levels in the blood subsequent to surgery, the patient was diagnosed with pancreatic pheochromocytoma. The present study additionally reviewed the associated literature concerning pheochromocytoma in order to improve the understanding of this rare clinical phenomenon. The aim of the present study is to highlight to surgeons that although patients may not present with typical clinical manifestations due to the non-functional status of the tumor, undiagnosed pheochromocytoma of the pancreas should be considered when surgeons observe an unexpected hypertensive crisis during pancreatic tumor surgery.