2232 Peribiliary Cysts Mimicking Primary Sclerosing Cholangitis and Cholangiocarcinoma

Abstract

INTRODUCTION: Peribiliary cysts are cystic dilatations resulting from obstruction of extramural peribiliary glands. They are usually benign, may arise from the intrahepatic and extrahepatic bile ducts and do not communicate with the biliary tree. They may, however, be confused with alternative diagnoses, resulting in unnecessary investigations with profound clinical implications. CASE DESCRIPTION/METHODS: A 42-year-old male was referred after recent diagnosis of cirrhosis, presumed secondary to primary sclerosing cholangitis (PSC), complicated by suspected cholangiocarcinoma. He presented with jaundice, weight loss and was noted to have nodular, cirrhotic liver with diffusely beaded appearance of the intra-hepatic biliary tree and central hilar prominence suggestive of mass lesion on outside imaging studies. ERCP was also interpreted as PSC with suspected cholangiocarcinoma. Brushing was negative for malignancy. Repeat MRI with MRCP showed multiple grape-like cystic structures surrounding the intrahepatic portal vein branches, resulting in compression of the intrahepatic bile ducts (Figure 1). These findings were consistent with peribiliary cysts. He subsequently underwent deceased donor liver transplantation. Gross examination of the explant revealed multiple benign bile duct cysts, which were focally multi-cystic with an exophytic semitranslucent cystic lesion in the hilum, which likely explains the prior imaging misdiagnosis as cholangiocarcinoma (Figure 2). Histologically, multiple cystic biliary structures were noted, lined by non-dysplastic cuboidal biliary type epithelium (Figure 3). DISCUSSION: Originally described in 1984, Peribiliary cysts are usually asymptomatic and often under- and misdiagnosed. The clinical importance of these structures arises from the fact that they may at times cluster together resembling multi-locular malignancy and mimic a dilated biliary tree. They may consequently be mistaken for entities such as biliary intraductal papillary mucinous neoplasm, cystic metastases, PSC, Caroli’s disease and importantly cholangiocarcinoma. In addition, they may also occasionally grow to compress the neighboring structures, resulting in biliary obstruction. High-resolution imaging with MRCP is a good modality for establishing the diagnosis. As highlighted by our case, given the prevalence of these lesions in patients with cirrhosis, awareness of this entity is critical to avoid misdiagnosis leading to inappropriate exclusion from transplantation in otherwise acceptable candidates.