Pseudotumoral Autoimmune Pancreatitis Mimicking a Pancreatic Cancer: A Very Difficult Disease to Diagnose

Autoimmune pancreatitis (AIP) is a rare disorder, although the exact prevalence is still unkown. It is a type of pancreatitis that is presumed to have an autoimmune aetiology, and is currently diagnosed based on a combination of 5 criteria. However, in this day and age, some patients with AIP are likely to be resected for the suspicion of malignancy. The authors report a case of pseudotumoral autoimmune pancreatitis, reviewing some literature about it and underlining the difficulty in the diagnosis. A 56-year-old patient was referred to our unit for upper abdominal pain. In his past medical history we note mellitus diabetes. The clinical examination was unremarkable. Laboratory data showed no abnormal values. Upper endoscopy showed antral gastritis. Transabdominal ultrasonography showed a hepatic steatosis and 5 angiomas. No computed tomography scan was made. Magnetic resonance imaging (MRI) showed 5 angiomas and a lesion of 20x20 mm of the pancreatic tail with decreased signal intensity on T1-weighted MR images, increased signal intensity on T2-weighted MR images. Due to concerns of pancreatic malignancy, the patient underwent open distal spleno-pancreatectomy. Histolo gical analysis of the resected specimen revealed no malignancy. Postoperatively, immunoglobulin G fraction 4 was slightly above of the upper limit of the normal range. After corticotherapy the patient is getting better. This case underlines the difficulties still encountered in the diagnosis of AIP. It has been frequently misdiagnosed as pancreatic cancer and caused unnecessary resection. In order to avoid unnecessary resections for an otherwise benign and easily treatable condition, it is urgent to refine diagnostic criteria and to reach an international consensus.