1446 A Rare Tumor in the Common Bile Duct: A Case Report of Plexiform Neurofibroma in the Common Bile Duct

Abstract

INTRODUCTION: Plexiform neurofibroma (PN) is a benign tumor that originates from nerves. This tumor is usually associated with neurofibromatosis type1 (NF1) and found in young patients. Common places of growth include head, neck and maxillofacial area. We report a rare case of common bile duct plexiform neurofibroma. CASE DESCRIPTION/METHODS: A 69-year-old female with history of cholecystectomy had incidental finding of dilated pancreatic duct (PD) on chest CT during pneumonia work up. Patient denied abdominal pain, weight loss, change in bowel habits, jaundice or itching. Physical examination was normal. Laboratory tests including CBC, LFT, CA 19-9 were unremarkable. MRCP showed extrahepatic biliary ductal dilation measuring 8 mm, minor intrahepatic ductal dilation involving left lobe, diffuse PD dilation from the ampulla to the body, involving the major and minor ducts with acinarization, and abrupt change in the main PD at the junction between the body and tail of pancreas, no masses were seen. EUS showed a CBD of 8 mm and a hypoechoic mass measuring 8.8 × 5.6 mm in the common hepatic duct (CHD) with mild dilation of the left hepatic duct measuring 6 mm. PD was dilated between the pancreatic head, and body measuring 8 mm without mural nodules, and 1.5 mm in the distal body and tail of pancreas. No obvious abnormality was visualized at the transition point. Previous findings were concerning for segmental main duct IPMN. ERCP performed, ampulla appeared normal without “fish mouth” appearance, and no filling defect in PD. Cholangiogram and biliary ductosccopy using Spyglass were performed and showed low-grade stricture in the CHD. Biliary epithelium was endoscopically normal in the strictured area. Biopsies obtained using Spybite. EUS and FNA of the hypoechoic area in the CHD was performed after the ERCP. Biopsies obtained with Spybite showed benign appearing ductal epithelium with fibrotic tissue. However, FNA cytology showed rare cluster of atypical glandular cells. Patient was referred to surgery. Pathology of the common bile duct showed a 7 mm plexiform neurofibroma with clear border resection without evidence of malignancy. DISCUSSION: PN is a rare benign tumor that develops from schwann cells in a bundle of nerves involving cutaneous nerves or internal nerve fibers. PN has substantial risk to transform into malignant peripheral nerve sheath tumors, therefore surgical resection is advised. PN is usually associated with NF1. However, few cases without clear etiology were reported with no link to the syndrome.