S3520 Type 1 Autoimmune Pancreatitis in a Teenager With Ulcerative Colitis

Introduction: Type 2 autoimmune pancreatitis (AIP) is a recognized complication of ulcerative colitis (UC), whereas Type 1 AIP—an IgG4-related sclerosing pancreatitis—is uncommon in this patient population and typically presents in older males. We present a case of recurrent pancreatitis in an 18-year-old man with UC. Investigations revealed elevated IgG4 levels and images demonstrating diffuse pancreatic strictures and parenchymal enlargement, consistent with Type 1 AIP. The patient showed a favorable response to glucocorticoid therapy. This case highlights a potential new association between AIP and UC and emphasizes early recognition and treatment. Case Description/Methods: An 18-year-old man with a history of biopsy-confirmed UC proctitis diagnosed 6 months prior, treated with oral and rectal mesalamine, and in endoscopic remission, presented with severe epigastric pain for 3 days. His symptoms began 1 month prior and were described as intermittent, “stabbing or throbbing”, non-radiating, and worse with eating, leading to fatigue and a 10-pound weight loss. On our examination, he appeared underweight with a body mass index of 17.7 kg/m2 (2nd percentile). Abdominal palpation elicited epigastric and generalized abdominal tenderness. Laboratory evaluation showed elevated serum lipase (5573 U/L, reference range 23-300 U/L) and serum IgG4 (2430 mg/dL, reference range of 4.0-86.0 mg/dL). Magnetic resonance cholangiopancreatography (MRCP) revealed features suggestive of acute pancreatitis involving the distal body and tail. There was an irregular pancreatic duct narrowing at the tail, and a dilated main pancreatic duct with abrupt cutoff at the head. Global parenchymal enlargement resulted in a “sausage-shaped” pancreas. No gallstones were identified on cross-sectional imaging. Prior MRCP studies were unavailable for comparison. The patient tolerated a diet and was discharged the following day on prednisone 40 mg daily ×2 weeks, followed by a slow taper over 7 additional weeks. Three weeks after discharge, repeat MRCP showed no evidence of acute pancreatitis. He continues maintenance on low-dose prednisone 2.5 mg daily. Pancreatitis has not recurred in 8 months, post-hospitalization. Discussion: The case presented highlights a unique association of Type 1 AIP that developed in the setting of ulcerative colitis. Narrow definitions of autoimmune conditions may not be appropriate. Given the overlap of AIP subtypes, a broad differential for new pancreatitis in UC patients should include IgG4 levels.