Intraductal Papillary Mucinous Neoplasm of the Duct of Santorini in the Absence of Pancreatic Divisum

Abstract

Introduction: Intraductal Papillary Mucinous Neoplasm (IPMN) is a mucin-producing cystic neoplasm of the pancreas that arises from the main pancreatic duct or one of the branch ducts. The literature has described a small number of IPMNs arising from the accessory duct of Santorini, with the majority of these cases in the setting of pancreatic divisum. We report a case of IPMN of the accessory duct of Santorini in a transgendered male patient without pancreatic divisum. We provide an endoscopic image of the fish-mouth appearance of the minor papilla, which has not been previously reported in the literature. Case Report: A 59-year-old transgender male presented with right-sided abdominal pain. Abdominal KUB revealed a severely enlarged liver silhouette. History revealed the patient to be transgendered, on estradiol, conjugated estrogens, and medroxyprogesterone acetate. Physical exam revealed no abnormalities and all labs, including liver function tests (LFTs) were within normal limits. CT showed hepatomegaly and a 5.5 X 5.5 X 21 mm cystic structure in the head and uncinate process, which was not contiguous with the extrahepatic common bile duct or main pancreatic duct with several enlarged retroperitoneal lymph nodes. On MRI/MRCP a tubular markedly hyperintense T2 lesion measuring 27 X 11 X 9 mm was present. This lesion appeared in continuity with the distal accessory pancreatic duct, which appeared mildly dilated with communication to the main pancreatic duct. On endoscopy, the major papilla appeared normal. The minor papilla had a fish-mouth appearance exuding mucoid material. EUS revealed tubulocystic dilation of the duct of Santorini measuring 1.3 X 0.6 cm. There was also dilation of a side-branch towards the communication between the accessory duct and the main pancreatic duct. The pancreatic duct was normal in contour and caliber through the remainder of the gland. Fine needle aspiration (FNA) was done and fluid analysis revealed amylase of 14780 Units/L and carcinoembryonic antigen (CEA) of 89.1. Cytological analysis of the fluid was nondiagnostic. Patient referred for Whipple, but declined surgical intervention.1257_A.tif Figure 1: No Caption available.1257_B.tif Figure 2: No Caption available.1257_C.tif Figure 3: No Caption available.Discussion: IPMNs are generally found incidentally on imaging. While guidelines for managmenent of MD- and BD-IPMNs are clear, an IPMN of the duct of Santorini is a rare entity with no diagnostic recommendations currently in place, though one study suggests surgical resection. Our patient has done well with endoscopic monitoring for 7 years.