Abstract
Introduction: Autoimmune pancreatitis (AIP) is a form of chronic pancreatitis that may be associated with IgG4 laden lymphoplasmacytic infiltration and fibrosis in multiple organs. It accounts for only a small percentage of all patients with chronic pancreatitis. It can present with abdominal pain, jaundice, recurrent acute pancreatitis, or clinical findings similar to pancreatic cancer. Radiologic findings can also be similar to the above. Therefore, it is important to fully understand the radiologic and histologic nuances of AIP. We review a case of a 20-year-old female who presented with abdominal pain and jaundice who was subsequently diagnosed with Type 2 AIP. Case Description/Methods: A patient with no known past medical history presented with one week of abdominal pain. Imaging demonstrated a normal appearing pancreas with a nodular area of soft tissue fullness at the junction of the pancreatic head and body. Patient returned a few weeks later with jaundice. Endoscopic retrograde cholangiopancreatography (ERCP) revealed a significant biliary stricture which was stented. EUS with biopsies demonstrated mild acute on chronic inflammation of the ampulla and mild acute inflammation of the pancreatic head as well as benign pancreatic parenchyma with edema, very focal fibrosis, and focal neutrophilic infiltrate in acini and intralobular small ducts. Steroids were prescribed leading to resolution of signs and symptoms. Discussion: Initial presentation of AIP can mimic that of other pancreatic pathology so further imaging with biopsy is necessary to make a final diagnosis. Type 1 and Type 2 AIP both have histologic findings of periductal infiltration of plasma cells and lymphocytes, peculiar storiform fibrosis, and venulitis. Type 1 typically has a high number of IgG4 positive plasma cells and can be associated with various systemic lesions related to IgG4 positive cell infiltrates. Type 2 is known for intraluminal and intraepithelial neutrophils in small to medium ducts and acini causing destruction of the duct lumen and is considered a pancreatic specific disease. In both types imaging tends to show diffuse parenchymal enlargement with delayed enhancement and ductal strictures without significant upstream dilatation. Treatment of AIP consists of steroids with Type 1 known to have relapses requiring re-treatment. Based on the histologic and radiologic findings a presumptive diagnosis of Type 2 AIP was made. Response to steroid treatment and no evidence of relapse confirmed the diagnosis.Figure 1.: A single severe stenosis seen in the lower third of the common bile duct.
Published Version
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