Michelle Godbee, MD, MPH, Muhammad Alsayid, MD, MPH, Shriram Jakate, MD, Jaimin Amin, MD, MS; Rush University Medical Center, Chicago, IL
Introduction: The most comprehensive criteria for diagnosing autoimmune pancreatitis (AIP) is the International Consensus Diagnostic Criteria, which uses five cardinal features: 1) imaging features, 2) serology (IgG, IgG4, ANA), 3) other organ involvement, 4) histopathology, and 5) response to glucocorticoids. Despite these criteria, we present a challenging case of AIP masquerading as pancreatic malignancy.
Methods: A 45-year-old man with occasional alcohol use presented to clinic with epigastric abdominal pain, jaundice, and weight loss over 2 weeks. Physical exam revealed stable vitals, scleral icterus, and epigastric tenderness. Laboratory revealed total bilirubin 7.7 mg/dL, conjugated bilirubin 4.4 mg/dL, alkaline phosphatase 573 U/L, AST 357 U/L, ALT 893 U/L, and normal lipase level. Ultrasound showed distended gallbladder without cholelithiasis. MRCP revealed a dilated common bile duct to 1.2 cm with abrupt narrowing at the distal CBD and enlarged pancreas. CT showed necrotic-appearing masses in the pancreatic head and tail. EUS revealed an enlarged and heterogenous pancreas with an irregular 35mm X 30mm hypoechoic area in the pancreatic head/uncinate with distal bile duct. ERCP revealed a single stenosis at the lower third of the main bile duct and a plastic biliary stent was placed. Serum IgG4 was elevated to 159 mg/dL. FNB results showed fibrotic stroma with crushed inflammatory cells (mostly lymphoid) and brushings were negative for malignancy. Liver enzymes improved after stenting, however he presented one month later with recurrent signs of biliary obstruction. Repeat ERCP now revealed two biliary strictures (proximal and distal). Brushings and biopsies were taken. Cytology/pathology showed similar findings to previous biopsies and immunostains did not reveal increase in IgG4 plasma cells. Given ongoing abdominal pain along with multiple biliary strictures and lack of complete normalization of liver enzymes, the patient was started on a prednisone trial starting at 60 mg daily with a weekly taper. Abdominal pain improved, liver enzymes normalized and biliary strictures resolved on CT and ERCP. Discussion: The patient presented with biliary obstruction and a necrotic pancreatic mass suspicious for malignancy. The patient met the criteria for AIP but was not started on steroids until malignancy was ruled out. In challenging cases where the diagnosis of AIP is not clear, a multidisciplinary approach along with patient-centered decision making becomes essential.
Figure 1. MRCP image of enlarged pancreas with ill-defined margins, moderate extrahepatic biliary ductal dilatation, and mild central intrahepatic biliary ductal dilatation with abrupt narrowing of the common bile duct at the pancreatic head
Figure 2. 35 mm x 30 mm ill-defined hypoechoic area in the pancreatic head/uncinate with abrupt cutoff of the common bile duct with upstream biliary dilation and loss of the pancreatic duct with normal upstream pancreatic duct
Figure 3. A single localized biliary stricture was found in the lower third of the main bile duct
Disclosures: Michelle Godbee indicated no relevant financial relationships. Muhammad Alsayid indicated no relevant financial relationships. Shriram Jakate indicated no relevant financial relationships. Jaimin Amin indicated no relevant financial relationships.