Pancreatic pseudoaneurysm mimicking pancreatic tumor: A case report and review of literature

Pancreatic pseudoaneurysm is a rare vascular complication of chronic pancreatitis (CP) or necrotizing pancreatitis with an incidence of 4% to 17%, but it is potentially life-threatening. It is well known that most pancreatic pseudoaneurysms are clinically associated with pancreatic pseudocysts and are usually in the peripancreatic body-tail. A minority of intrapancreatic pseudoaneurysms occur in the absence of pseudocyst formation. Noninvasive computed tomography (CT) and magnetic resonance imaging (MRI) are most commonly used examinations for screening pancreatic pseudoaneurysms. Notably, the rare intrapancreatic pseudoaneurysm in the pancreatic head can mimic a hypervascular solid mass and be misdiagnosed as a pancreatic tumor. We report the case of a 67-year-old man who had been admitted to our hospital due to recurrent abdominal pain for 1 mo that was aggravated for 5 d. CT and MRI revealed a mass in the pancreatic head with significant expansion of the main pancreatic duct and mild atrophy of the pancreatic body-tail. He was admitted to the department of hepatobiliary and pancreatic surgery due to the possibility of a pancreatic tumor. The patient was then referred for endoscopic ultrasonography (EUS) with possible EUS-FNA. However, EUS showed a cystic lesion in the pancreatic head with wall thickness and enhancing nodules, which was doubtful because it was inconsistent with the imaging findings. Subsequently, color doppler flow imaging demonstrated turbulent arterial blood flow in the cystic lesion and connection with the surrounding vessel. Therefore, we highly suspected the possibility of CP complicated with intrapancreatic pseudoaneurysm, combined with the patient's long-term drinking history and the sonographic features of CP. Indeed, angiography revealed an oval area of contrast medium extravasation (size: 1.0 cm × 1.5 cm) at the far-end branch of the superior pancreaticoduodenal artery, and angiographic embolization was given immediately at the same time. EUS is an important differential diagnostic tool when pancreatic pseudoaneurysm mimics the imaging appearance of a hypervascular pancreatic tumor.