S3343 Nodules in Biliary Tree: Decoding Rare Neoplastic Phenomenon

Introduction: Intraductal papillary neoplasm of the bile duct (IPNB) is rare, premalignant disease accounting for 4%-15% of bile duct tumors. The incidence is higher in East Asia. Hepatolithiasis and liver fluke infections are probable risk factors. However, most IPNBs are sporadic. As these tumors were morphologically similar to intraductal papillary mucinous neoplasm (IPMN) of pancreas; initially they were considered as intraductal papillary neoplasm of liver. As similar tumors were also observed in extrahepatic bile duct, these tumors were officially renamed in 2010 in revised World Health Organization Classification of Tumors of the Digestive System as IPNB. It is important to recognise this recently characterized entity as IPNB has better prognosis than cholangiocarcinoma after complete surgical resection despite invasive features. Case Description/Methods: A 52-year-old woman presented with recurrent right upper quadrant pain for 2 months. There was no history of fever, jaundice or anorexia and weight loss. Laboratory investigations revealed normal blood count, normal inflammatory markers and mildly increased gamma-glutamyl transferase. Ultrasonography showed a complex cystic lesion in left lobe of liver. Further characterisation of the lesion was done by contrast-enhanced computed tomography (CECT) and magnetic resonance cholangiopancreatography (MRCP). CECT and MRCP revealed a complex cystic mass with intraluminal enhancing polypoidal projections and dilated peripheral bile ducts communicating with cystic mass suggestive of intraductal papillary neoplasm of the bile duct (IPNB). The patient underwent left lateral segmentectomy of liver. Histopathology showed large cystically dilated intrahepatic bile ducts with presence of papillary and glandular configuration. The papillae were lined by tumor cells with invasion of underlying subepithelial stroma confirming diagnosis of IPNB with invasive carcinoma. Discussion: IPNB is a preinvasive neoplasm typically affecting middle aged adults. It can involve intra- as well as extrahepatic biliary tree and is characterised by presence of intraluminal projections with fibrovascular core. Complete surgical resection remains the primary treatment strategy, necessitating comprehensive multimodality preoperative evaluation for an ideal textbook outcome. This case of IPNB underscores the complexity of diagnosis, emphasizing the importance of comprehensive imaging and surgical intervention in managing this rare biliary neoplasm.