Adenomyomatous Hyperplasia of the Ampulla of Vater Masquerading as Malignancy: A Case Series

Abstract

Introduction: Adenomyomas are benign lesions rarely seen in the ampulla of Vater, composed of heterotopic pancreatic tissue. Patients may present with biliary obstructive, abnormal liver tests, and/or imaging abnormalities, but may be found incidentally. Endoscopic sampling of the papilla may show epithelial cell atypia suggesting dysplasia. Patients often undergo invasive surgical resection for presumed malignancy. In this case series 2 patients underwent pancreaticoduodenectomy for distal common bile duct (CBD) brush cytology adequate for adenocarcinoma with ultimate surgical pathology diagnosis revealing benign adenomyomatous hyperplasia (AH). Case 1: A 74-year-old female with a history of cholecystectomy presents with recent colonic surgery complicated by an intra-abdominal abscess. Computed tomography (CT) imaging showed new significant dilatation of the CBD without pancreatic mass. The patient underwent endoscopic ultrasound (EUS), and endoscopic retrograde cholangiopancreatography (ERCP) to further investigate dilatation. Gross dilatation of the CBD to 18 mm down to the ampulla and pancreatic duct prominence of 3.5 mm was confirmed with EUS. Cholangiogram showed significant upstream CBD dilation and a 1-cm stricture of the distal CBD. She underwent sphincterotomy, cytology brushings of the distal CBD, and biliary stenting. Cytology was positive for malignant adenocarcinoma. A pancreaticoduodenectomy was performed. Surgical pathology showed AH of the ampulla of Vater and incidental focal low-grade pancreatic intraepithelial neoplasia. Her postoperative course has been uneventful and she is doing well. Case 2: A 73-year-old female with a history of cervical carcinoma, chronic kidney disease, and cholecystectomy presents with epigastric pain, back pain, dark urine, and weight loss. MRCP showed CBD dilatation to 20 mm. EUS revealed prominent pancreatic duct (3 mm) and CBD dilatation to 20 mm (10 mm in the distal CBD). Cholangiogram showed a shelf with abrupt tapering in the distal CBD. She underwent sphincterotomy, cytology brushings of the distal CBD, and biliary stenting. Cytology showed distal CBD high-grade biliary intraepithelial neoplasia; could not exclude adenocarcinoma. After pancreaticoduodenectomy, surgical pathology specimens of the ampulla of Vater showed features of AH without carcinoma. Her course has been uneventful after postoperative recovery. Discussion: Although uncommon, AH should be considered in the differential of CBD dilatation. Brush cytology may be highly suggestive of dysplasia and lead to surgical resection. Gastroenterologists should be aware of AH of the ampulla of Vater as a rare benign clinical entity which may mimic a pancreaticobiliary malignancy. Disclosure - Dr. Shah - Speaker’s Bureau: US Endoscopy.