S1459 Immune Checkpoint Inhibitor-Induced Pancreatic Injury: An Atypical Presentation

Abstract

INTRODUCTION: Immune checkpoint inhibitors (ICI) are effective in the treatment of several advanced cancer types. ICI-pancreatic injury (ICI-PI) is uncommon and often asymptomatic with incidentally elevated pancreatic enzymes. We present a case of ICI-PI mimicking autoimmune pancreatitis (AIP) with obstructive jaundice. CASE DESCRIPTION/METHODS: A 60-year-old male with acral melanoma metastatic to the liver was treated with four cycles of nivolumab and ipilimumab. After three cycles of maintenance nivolumab, surveillance positron emission tomography (PET) revealed diffuse fluorodeoxyglucose (FDG)-avidity of the pancreas with peripancreatic fat stranding (Image 1). He endorsed mild abdominal discomfort with an elevated lipase 10x the upper limit of normal (Table 1). He had no gallstones on imaging and socially drank alcohol. ANA was negative with normal IgG4. He was given a diagnosis of ICI-PI and treated with intravenous fluids and discharged on a 14-day steroid taper and lab monitoring. Three weeks after completing the steroid taper, he presented with worsening abdominal pain and gray colored stool. Labs showed elevated liver tests consistent with a cholestatic obstructive pattern. Computed tomography (CT) revealed diffuse mild enlargement of the pancreas. MRCP showed dilated extrahepatic bile duct up to 11mm with an intrapancreatic stricture. Endoscopic ultrasound (EUS) showed diffusely lobular pancreas with hypoechoic areas and intervening hyperechoic standing. The pancreatic duct was not dilated. The bile duct was dilated and abruptly narrowed as it entered the pancreatic head. Fine needle aspiration (FNA) of the pancreatic head with 25G needle revealed pancreatic acini and focal findings suggestive of chronic pancreatitis without metastatic melanoma (Image 2). A diagnosis of ICI-PI mimicking AIP was made. He received high dose oral steroids with a long taper. His liver enzymes normalized. Repeat PET showed interval resolution of pancreatic FDG-avidity and peripancreatic fat stranding with continued remission of melanoma. DISCUSSION: This is a unique case of ICI-PI evolving into obstructive jaundice and resolving with steroids. Although he had negative serologies, his imaging and clinical course mimicked AIP. Both ICI related adverse events and AIP are T-cell driven processes suggesting a possible similar pathogenesis. The incidence of ICI-PI will likely rise with the increasing use of ICIs; thus, awareness of ICI-PI and its variable presentation are clinically salient.Table 1.: Liver enzymes, total bilirubin and lipase from the last cycle of nivolumab therapy through both hospitalizations. Normal aspartate aminotransferase (AST) is 0–40 IU/L. Normal alanine aminotransferase (ALT) is 0-32 IU/L. Normal alkaline phosphatase (ALP) is 39-117 IU/L. Normal total bilirubin is 0–1.2 mg/dL. Upper limit of normal lipase is 51 U/LFigure 1.: Image 1. Positron emission tomography (PET) imaging. A. Prior to nivolumab therapy. B. After three cycles of maintenance nivolumab. C. After high dose oral steroids and normalization of liver enzymes.Figure 2.: Image 2. Biopsy obtained during endoscopic ultrasound (EUS). A. Benign pancreatic acini and focal findings suggestive of chronic pancreatitis on hematoxylin and eosin (H&E) stain. B. SOX10 stain with control. SOX10 is a melanoma marker and thus no metastatic melanoma identified.