A Rare Case of Ampullary Carcinoid Tumor: Emphasizing the Need for EUS for Diagnosis

Abstract

Introduction: Ampullary carcinoids are extremely rare neuroendocrine tumors, comprising <0.05% of all gastrointestinal carcinoids and <2% of all ampullary tumors. Case Report: A 75-year-old white woman presented with nausea/vomiting with abdominal pain for 1 day, preceded by dizzy spells of 2 weeks’ duration. She had prior history significant for coronary bypass surgery almost a decade ago, and hypertension. The vitals were stable and initial lab work, including complete blood count, kidney profile, amylase/lipase, and liver function tests were unremarkable. The patient was unable to get an MRI due to recent shoulder prosthesis, and a CT with a pancreas protocol was obtained, which showed severe intra- and extra-hepatic biliary ductal dilation with a 1.1 x 0.5-cm mass near the ampulla, raising concerns for possible neoplastic process. Endoscopic ultrasound (EUS) imaging revealed a very dilated (1.2 cm) CBD that tapered towards a bulbous ampulla. During ERCP, a sphincterotomy was performed; there was no evidence of any strictures and biopsies of the bulbous ampulla were obtained. Immunohistochemical stains revealed that the tumor cells expressed pancytokeratin AE1/AE3 (patchy), synaptophysin (strong and diffuse), chromogranin (patchy), but congo red stain excluded any evidence of amyloid deposition. There was no increased mitotic activity, and overall findings supported well-differentiated neuroendocrine tumor (carcinoid tumor). Discussion: Ampullary carcinoid tumor was first described in 1888 by Lubarsch. The most common presenting symptoms may include obstructive jaundice (>60%), abdominal pain (<40%), weight loss (<10%), and pancreatitis (˜5%). The sensitivity of octreotide scintigraphy decreases with smaller size of tumor and decreased tumor somatostatin receptor expression. Endoscopic biopsy during EGD has limited value and has a high failure rate due to the sub-epithelial nature of this tumor. Diagnosis can be established by histological and immune-histochemical analysis of lesion with EUS-FNA. EUS is superior to CT and equivalent to MRI for tumor staging. Unlike other midgut carcinoids, the size of the ampullary carcinoid is a poor predictor of metastatic potential, with varying rates of metastasis at different tumor sizes. Since these tumors have a high propensity of lymph node metastasis, unlike other duodenal carcinoids, local resection of ampullary carcinoid is technically difficult and pancreatico-duodenectomy has been suggested for complete resection of the lesion. Predicting metastases among small intestinal carcinoids using a gene expression profiling (GEP)-based mathematical model is an emerging strategy to improve detection accuracy.