Autoimmune pancreatitis presenting as simultaneous masses in the pancreatic head and gallbladder

Autoimmune pancreatitis is a rare variant of chronic pancreatitis characterized by pancreatic ductal narrowing and pancreatic parenchymal edema on computed tomography and rarely with intermittent attacks of abdominal pain. Recently, it has been found to be a systemic disease with lymphoplasmacytic infiltration that has been associated with several autoimmune diseases and described in multiple organs including the extrahepatic bile duct, liver and gallbladder.

We describe the clinical, radiographic and histopathologic aspects of a patient who presented with synchronous masses in the pancreatic head and gallbladder. Postoperatively, the patient's jaundice subsided and IgG4 levels, which were drawn one week postoperatively, were all within normal limits. Nonetheless, immunohistochemical staining for IgG4 was positive.

Autoimmune pancreatitis is the most common benign entity identified in patients that underwent pancreaticoduodenectomy for presumed pancreatic adenocarcinoma. Our patient with autoimmune pancreatitis presented with simultaneous inflammatory masses in the gallbladder and pancreatic head, an association not previously reported. Preoperative evaluation of IgG4 or autoantibody levels may have obviated the need for an operation. Therefore, we have begun screening for elevated serum IgG4 concentrations to identify patients with possible autoimmune pancreatitis who present without definitive pathological or radiographic evidence for malignancy. If pre-operative diagnosis is not made, immunohistochemical staining of pathology specimens can confirm the diagnosis.