Ampullary Carcinoid Tumors: Unsuspected Diagnosis in Two Patients with Biliary and Pancreatic Ductal Obstruction Diagnosed by EUS-FNA

Abstract

Purpose: Background: Ampullary carcinoid tumors are rare and often pose a diagnostic challenge due to the limitations of conventional endomucosal biopsies in confirming the diagnosis. Preoperative endoscopic ultrasound with fine needle aspiration (EUS-FNA) has not been studied extensively for this disease entity. Case Series: 1-An asymptomatic and previously healthy 46-year-old male was referred for evaluation of microcytic anemia. Physical exam was unremarkable. Colonoscopy was performed and was normal. Upper endoscopy showed an enlarged Ampulla of Vater. Mucosal biopsies showed non-specific inflammatory changes. EUS revealed a round hypoechoic 23 mm ampullary subepithelial mass. Both common bile duct and pancreatic duct were dilated up to 4 and 7 mm respectively. This was staged as T2N1Mx on EUS. FNA of the mass revealed a low grade neuroendocrine tumor. The patient was referred for pancreaticoduodenectomy (PD), and final pathology revealed carcinoid tumor staged as T2N1M0. Immunostaining for cytokeratin and synaptophysin was positive. Staining for chromogranin was negative. The postoperative course was unremarkable, and imaging and clinical follow up after six months were unremarkable for tumor recurrence. 2-A 53-year-old previously healthy female presented with four-week history of painless jaundice, pruritis, and 20-pound weight loss. Physical exam revealed scleral icterus, with mild hepatomegaly. Abdominal ultrasound and CT scan showed dilated intra and extrahepatic biliary ducts without a pancreatic mass. EUS showed a small 18 mm subepithelial lesion in the ampulla originating form the submusocsa and extending to the muscularis propria causing both pancreatic and biliary duct dilation staged as T3N1Mx. FNA of the lesion showed high grade neuroendocrine tumor with positive immunostaining for cytokeratin, synaptophysin, and chromogranin. The patient underwent pylorus-sparing PD. Final pathology confirmed a high grade neuroendocrine carcinoma, staged as T3N1M0. Discussion: Ampullary carcinoid tumors are extremely rare, and only 100 cases have been reported in the literature. Few reported cases emphasized the role of EUS-FNA for the diagnosis and staging of this disease in patients presenting with biliary and pancreatic duct obstruction, where preoperative diagnosis is challenging. Compared to other enteropancreatic carcinoids, ampullary carcinoids often display malignant behavior which is not predicted by primary tumor size. Potentially curative therapy involves complete resection with adequate regional lymphadenectomy. EUS with FNA provides accurate diagnostic and staging information for directing appropriate therapy.