3013 Fish Mouth Ampulla: Classic Main Duct Intraductal Papillary Mucinous Neoplasm

Abstract

INTRODUCTION: Intraductal Papillary Mucinous Neoplasms (IPMNs) were first identified in 1982 and there have been increasing rates of diagnosis of IPMNs in recent years with the improvement of imaging modalities. Due to the indolent course of IPMNs, many patients may initially remain asymptomatic for many years. IPMNs should be acted on quickly after diagnosis as they can progress to malignancy. We present a case of a patient who presented with symptoms similar to pancreatitis but was found to have a main duct IPMN with the classic fish mouth appearance of the ampulla. CASE DESCRIPTION/METHODS: A 62-year-old male presented to an outside hospital with epigastric abdominal pain and nausea. RUQ Ultrasound revealed normal liver and gallbladder with heterogenous echotexture within an enlarged pancreas. Abdominal CT Scan revealed a low density heterogenous, contrast enhancing, possibly multicystic lesion at the uncinate process and near the pancreatic head measuring 3.6 × 3.6 cm with dilation of the pancreatic duct. MRCP revealed a dilated pancreatic duct at 6 mm and a cystic appearing pancreatic mass involving uncinate process and portion of the right pancreatic head concerning for intraductal papillary mucinous neoplasm. He was transferred to our facility for formal Gastroenterology evaluation. EGD was performed and revealed a markedly dilated ampulla with mucinous discharge, with classic “fish mouth” appearance. The pancreatic duct was diffusely dilated from the tail to ampulla, up to 17 mm in the head/neck. A cystic lesion measuring 41 × 35 mm adjacent to the main pancreatic duct extending to the uncinate was noted. FNA was performed and pathology confirmed the diagnosis of main duct IPMN. He successfully underwent a Whipple procedure. DISCUSSION: This case illustrates the importance of recognizing a classic endoscopic feature of main duct IPMN: the fish mouth ampulla of Vater. There are three types of IPMNs: main duct, side branch and mixed. MD-IPMNs have the most malignant potential of the three and should be acted on promptly with surgical referral for resection. Approximately 65% of MD-IPMNs are malignant, compared to 20% for side branch IPMNs. Due to the indolent course of IPMNs, many patients will remain asymptomatic for many years. Eventually, patients will present with symptoms similar to pancreatitis. Despite the lack of clear consensus for management of pancreatic cystic lesions between multiple guidelines, all agree that MD-IPMNs should be surgically resected due to the high malignant potential.