S1733 Exceedingly Rare Coexistence of Metamorphosis of Tubulovillous Adenoma of the Ampulla to Adenocarcinoma with Small Bowel Gastrointestinal Stromal Tumor - Case Report and Review of the Literature

Abstract

Introduction: This is a unique case of a patient with 3 tumors, which include one benign tumor, tubulo-villous adenoma of the ampulla of Vater (TVAoA), and 2 extremely rare malignant tumors, adenocarcinoma of the ampulla of Vater arising from TVAoA and gastrointestinal stromal tumor (GIST) involving the jejunum. Based on literature review, this is the first case of ampullary adenocarcinoma coexisting with GIST. Distal duodenal polyps are uncommon and have preponderance to occur in and around the ampulla of Vater. We report a case of a 77-year-old male who was admitted for painless obstructive jaundice with a 40-pound weight loss over a 2-month period, and who was subsequently diagnosed with 3 tumors. Case Description/Methods: A 77-year-old man was admitted for generalized weakness with associated weight loss of 40 pounds in the previous 2 months and was noted to have painless obstructive jaundice. Computed tomography (CT) of the abdomen and pelvis and magnetic resonance cholangiopancreatography were consistent with a polypoid mass at the level of the common bile duct (CBD) and ampulla of Vater with CBD dilatation. The same lesions were visualized by endoscopic retrograde cholangiopancreatography. Histopathology of endoscopic forceps biopsy showed tubulo-villous AoA (TVAoA). Histopathology of the surgical specimen of the resected ampulla showed adenocarcinoma arising from the TVAoA. Abdominal and pelvic CT also showed a coexisting heterogeneously enhancing, lobulated mass in the posterior pelvis originating from the jejunum (Figure). The patient underwent resection of the mass and jejunojejunal anastomosis. The histopathology of the resected mass confirmed it as a high-grade GIST. Discussion: AoA can occur sporadically and in a familial inheritance pattern in the setting of FAPS. We emphasize screening and surveillance colonoscopy when one encounters AoA in upper endoscopy to check for FAPS. AoA is a premalignant lesion, particularly in the setting of FAPS, that carries a high risk of metamorphism to ampullary adenocarcinoma. Final diagnosis should be based on a histopathologic study of the surgically resected ampullary specimen, and not on endoscopic forceps biopsy.This case is unique because he had 3 tumors and rare coexistence, which included one premalignant TVAoA and 2 malignant tumors: ampullary adenocarcinoma arising from the TVAoA and coexisting jejunal GIST.Figure 1.: Figure1A: CT abdomen and pelvis with contrast. Obstructed distal common bile duct due to a 9 mm polypoid intraluminal (pointed yellow arrows) lesion in the distal CBD. Figure1B: CT of the abdomen and pelvis with contrast. Heterogeneously enhanced lobulated mass with punctate calcifications (pointed yellow arrows) in the posterior pelvis originating from the serosal surface of the pelvic small bowel. Figure1C: Endoscopic retrograde cholangiopancreatography (ERCP) showed abnormal papilla with polypoid mass. Sphincterotomy and deep cannulation procedures were performed and confirmed by fluoroscopy. It showed common bile duct dilatation, and there was an abrupt cutoff at the distal aspect. Figure1D: High-power photomicrograph showing high-grade glandular dysplasia (hematoxylin and eosin stain, 200 X original magnification) Figure1E: A broad base ampullary mass with red fogerty cath was advanced from the cystic duct down through the ampulla to the duodenum. Figure1F: Pedunculated GIST arising from the small bowel approximately 150 cm proximal to the ileocaecal valve.