1333 Not so Small Biliary Obstruction: A Case of Small Cell Carcinoma of the Ampulla of Vater

Abstract

INTRODUCTION: Small cell carcinomas commonly arise in the lung, but can also originate in extrapulmonary sites. Extrapulmonary small cell carcinomas are rare and are most frequently found in the female genital tract, gastrointestinal tract and genitourinary tract. Small cell carcinoma of the ampulla of Vater is exceedingly rare, and there are currently less than 15 documented case reports. The neuroendocrine features of small cell carcinoma of the lung and extra pulmonary sites appear to be similar. CASE DESCRIPTION/METHODS: 64-year-old male with past medical history of hypertension and coronary artery disease presented to our hospital with weight loss and jaundice. At time of admission, labs demonstrated AST 114 U/L, ALT 168 U/L, alkaline phosphatase 715 U/L, total bilirubin 5.8 mg/dL (Dbili 4.5), INR 1.1, platelet 271 k/mm3, and albumin 3.5 g/dL. Notable findings on physical exam included jaundice and scleral icterus. Ultrasound of the biliary tree showed no visible stone. ERCP showed an ulcerated, bleeding ampullary mass. Subsequent cholangiogram revealed a distal bile duct stricture measuring approximately 1.5 cm with shelf effect from extension of ampullary mass into the bile duct. Sphincterotomy was performed, followed by distal bile duct biopsy and stent placement. Pathology report of ampullary mass showed findings consistent with small cell neuroendocrine carcinoma. Immunohistochemical staining showed malignant cells were positive for synaptophysin and chromogranin and negative for cytokeratin AE1/3 and CD45. Patient underwent a Whipple procedure with specimen demonstrating a 4.2 cm × 2.8 cm exophytic mass at the ampulla with invasion into the pancreas. Five of twenty peripancreatic lymph nodes were positive for metastatic small cell carcinoma. Following resection our patient was started on adjuvant chemotherapy with cisplatin and etoposide. DISCUSSION: The most common tumor involving the ampulla of Vater is adenocarcinoma. Small cell neuroendocrine carcinoma of the ampulla of Vater accounts for no more than 2% of ampullary malignancies. This case illustrates that although biliary obstruction is commonly attributed to choledocholithiasis and other intrinsic or extrinsic tumors, rarer forms of malignancy should be considered in the differential. Careful assessment of the ampulla during ERCP can aid with diagnosis. Final diagnosis is challenging and can only be confirmed with histopathological examination. Treatment involves a multidisciplinary approach involving surgical resection and chemotherapy.