br Discussion IPNB is a papillary tumor containing
Discussion IPNB is a papillary tumor containing biliary epithelium and grows within the bile duct. It can spread everywhere along the extra- and intrahepatic bile duct epithelium. IPNB has been categorized into a spectrum ranging from premalignant lesions to invasive cholangiocarcinomas. Intraductal papillary neoplasm, low-, intermediate-, high-grade intraepithelial neoplasia, and invasive carcinoma have been defined in the World Health Organization International Classification of Diseases. The most common manifestations of IPNB are abdominal pain, jaundice, and cholangitis. Hemobilia has been rarely observed in IPNB. Several case reports have described unusual presentations of IPNB. In cyst-forming IPNBs, mucinous fluid has been associated with hemorrhage in two of nine cases, with bleeding mimicking a hepatic hemorrhagic cyst. Sen et al reported a rare case of benign biliary papillomatosis in a choledochal cyst presenting with hemobilia. In the current case, the papillary tumor dilated the bile duct and ruptured a blood vessel, causing hemobilia. Clinically, diagnosing IPNB definitively is difficult. Our patient presented with repeated upper GI hemorrhage and cholangitis, which were misleading. The tumor caused intermittent partial obstruction of the bile duct mimicking bile duct stones; therefore, imaging may be beneficial. Ultrasonography revealed nonshadowing intraductal echogenic lesions and CT showed intraductal noncalcified soft-tissue masses with asymmetric wall thickening. Cholangiography revealed an intraductal papillary mass and a serrated bile duct margin. However, several studies have reported that rilpivirine intraductal masses were evident in only 41.2% and 50% of ultrasonography and CTs, respectively. Biliary tract dilatation is the most common radiological finding in IPNB. IPNB has been histologically classified into four types: pancreatobiliary, intestinal, gastric, and oncocytic. More than half of all cases contain malignant components, with these being most common in the pancreatobiliary type. Most cases of IPNB are intraductal papillary neoplasm with high-grade intraepithelial neoplasia or an associated invasive carcinoma. A complete surgical resection with negative margin may provide a survival benefit. Because the current case presented with repetitive hemobilia and cholangitis and was of a pancreatobiliary type, we performed a left lateral liver segmentectomy and achieved a negative resection margin. All IPNBs should be treated because, with or without mucus secretion, they often repeatedly cause obstructive jaundice and cholangitis, even if the tumor is benign. If surgery is planned, preoperative cholangioscopic examination is crucial. The extent, spread, and location of a tumor must be carefully evaluated. Preoperative CT can be used to assess the depth of invasion and involvement of lymph node metastasis. Patients with distant metastasis should be ruled out prior to surgery. IPNB should be treated as a similar level of cholangiocarcinoma if surgery is indicated. Major hepatectomy or limited resection can be considered for the surgical procedure. A frozen section examination of the cut surface of the bile duct may be performed intraoperatively to achieve a malignancy-free margin of resection. Regional lymph node dissection also should be performed. Several studies have demonstrated that IPNBs originate from normal epithelium and proceed to low-, mid-, and high-grade intraepithelial neoplasia and to invasive carcinoma. Biliary intraepithelial neoplasia (BilIN) is a precursor related to the development of invasive carcinoma. Numerous similar molecular genetic changes occur in the BilIN and IPNB lineages. However, certain authors have reported differences and inconsistent results in the molecular genetic changes between the two lineages. Cyclin D1, a regulator of the cell cycle, plays a role in the development and progression from low grade to the invasive carcinoma in both the IPNB and BilIN lineages. The positive rate of cyclin D1 expression is found to be similar to that in IPNB (53%) and BilIN (43%); however, Itatsu et al reported a different outcome, 65% in IPNB and 20% in BilIN lineages. The expression rate of the other molecular events, such as p16, c-myc, b-catenin, SMAD4/DPC4, and p53, are also reported differently by some authors.