S1453 Atypical Presentation of Type II Autoimmune Pancreatitis in a Pediatric Patient With Subsequent Development of Crohn's Disease

Abstract

INTRODUCTION: Type 2 Auto Immune Pancreatitis (AIP) is a rare diagnosis with developing diagnostic criteria. These criteria are based on cardinal features: histology, imaging, serology, other organ involvement, and response to steroids (Figure 1). Typically, type II AIP patients with concomitant IBD are diagnosed at mean age of 35 years old with no gender predominance. More commonly, UC rather than Crohn's disease is associated with type II AIP. Here we present a rare case of AIP closely followed by Crohn’s colitis in a young boy. CASE DESCRIPTION/METHODS: An 11 year old Egyptian boy with no past medical history presented with pruritus, jaundice, fevers, chills, without abdominal pain of 6 days duration. Bilirubin was noted to be elevated at eleven. MRCP revealed distal CBD stricture and pancreatic head fullness, with no obvious mass. EUS/ERCP (Figures 2 and 3) showed the bile duct dilated at 10 mm tapering and disappearing into a vague mass-like area in the head of the pancreas (15–20 mm). Pancreatic duct was normal. Parenchymal features of the pancreas included hyperechoic foci without shadowing and hypoechoic lobules. Bile duct brushings and biopsies showed benign inflammatory cells. Subsequently, we performed biliary sphincterotomy and a common bile duct stent was placed. This resulted in improvement of bilirubin from eleven to normal in 6 months. Serum ANA and IgG4 were normal. Eight months after initial presentation, the patient developed bloody diarrhea, abdominal pain, nausea, vomiting, and weight loss. Endoscopy and colonoscopy showed deep ulcers in the colon, nodular inflammation in the stomach as well as the duodenum with biopsies confirming chronic inflammatory bowel disease suggestive of Crohn's colitis. The patient's treatment is immunosuppressive agents with excellent response to steroids. DISCUSSION: Autoimmune pancreatitis is rare but progressively more frequently recognized due to increased awareness and evolving diagnostic criteria. While adult AIP has been examined closely with expert consensus deciding on diagnostic guidelines, pediatric AIP is a newer disease with unclear diagnostic criteria. In fact, recent literature has suggested that pediatric AIP may be underdiagnosed. Our case reports highlights the need to revisit diagnostic criteria of AIP especially in pediatric patients. Our case also underscores the importance of prompt recognition so as to abate symptoms.Figure 1.: Table of International Diagnostic Criteria for Type 2 Autoimmune Pancreatitis.Figure 2.: EUS Findings.Figure 3.: ERCP findings.