Biliary intraductal papillary mucinous neoplasia: three case reports.

Intrahepatic cholangiocarcinoma is subdivided as mass-forming, periductal-infiltrating, and intraductal-growing types. Intraductal-growing type is an entity described in recent years as mucin-producing intrahepatic cholangiocarcinoma or intrahepatic (biliary) intraductal papillary mucinous neoplasia (b-IPMN). b-IPMN is classified as adenoma, borderline tumor, carcinoma in situ, and carcinoma, from benign to malignant. Using a different classification, b-IPMNs are subdivided into intestinal, pancreatobiliary, gastric, or oncocytic based on morphology of the cells forming the lesion and expression of MUC1, MUC2, and MUC5 gene proteins in the mucin family. The clinical and histopathological features of b-IPMN diagnosed in three cases are presented herein. Case 1 was classified as borderline. Case 2 was diagnosed as carcinoma in situ. Case 3 had large invasive areas, and was diagnosed as carcinoma. In all three cases, immunohistochemical investigation revealed MUC1 and MUC5AC to be positive, and MUC2 to be negative. We present herein three cases diagnosed with the clinical and pathological findings of a new entity in the literature, b-IPMN, and we discuss the macroscopic, histological, and immunohistochemical features.