Precursor neoplastic lesions of the biliary tract

Mucin-producing Cystic Hepatobiliary Neoplasms: Updated Nomenclature and Clinical, Pathologic, and Imaging Features

Cystic hepatobiliary neoplasms with mucin-producing epithelium-mucinous cystic neoplasm of the liver (MCN) and intraductal papillary neoplasm of the bile duct (IPNB)-are rare and distinct entities that have unique clinical, pathologic, and imaging features. They are differentiated pathologically by the presence of subepithelial ovarian-like hypercellular stroma (OLS), which is the defining histopathologic feature of MCN. MCN is commonly a benign, large, solitary, symptomatic, multiloculated cystic mass without biliary communication that occurs in middle-aged women. On the other hand, IPNBs are a heterogeneous spectrum of tumors, which are commonly associated with invasive carcinoma, occur in older patients, and can be differentiated from MCN by communication with the biliary tree, intraductal masses, associated biliary ductal dilatation, and absent OLS. Understanding of these rare neoplasms has grown and evolved over time and continues to today, but uncertainty and controversy persist, related to the rarity of these tumors, relatively recent designation as separate entities, inherent clinicopathologic heterogeneity, overlapping imaging features, and the fact that many prior studies likely included MCN and cystic IPNB together as a single entity. Confusion regarding these neoplasms is evident by historical inconsistencies and nonstandardized nomenclature through the years. Awareness of these entities is important for the interpreting radiologist to suggest a particular diagnosis or generate a meaningful differential diagnosis in the appropriate setting, and is of particular significance as MCN and cystic IPNB have overlapping imaging features with other more common hepatobiliary cystic masses but have different management and prognosis. Online supplemental material is available for this article. Work of the U.S. Government published under an exclusive license with the RSNA.

Precursors to Cholangiocarcinoma

Cancers of the biliary tract include intra- and extrahepatic cholangiocarcinomas and gallbladder cancer. Biliary tract cancers are diseases with unfavorable prognoses. In recent years, several lesions have been described as precursors that precede biliary cancers. They include flat and microscopic lesions known as biliary intraepithelial neoplasia, macroscopic and tumor-forming intraductal papillary biliary neoplasia, intraductal tubular neoplasia, and mucinous cystic neoplasm of the bile duct. These conditions are rarely diagnosed, while their natural history and progression to cancer have yet to be adequately characterized. This review examines the epidemiology, pathology, molecular biology, diagnosis, and therapy of these various precursors. Further research is required if we are to better understand this evolving field and improve the prevention and early detection of bile duct cancer.

Premalignant lesions of cholangiocarcinoma: characteristics on ultrasonography and MRI

BACKGROUND AND OBJECTIVE

Cholangiocarcinoma (CCA) is an aggressive malignancy with high prevalence rate in Asia. The CCA premalignant lesions, including Biliary intraepithelial neoplasia (Bil-IN) and Intraductal papillary neoplasm of biliary tract (IPNB), share a common carcinogenesis; however, on imaging, patterns of presentation are different. Patterns and imaging characteristics on ultrasonography (US) and Magnetic resonance imaging (MRI) of both Bil-IN and IPNB are reported herein.

METHODS

In this retrospective study of imaging findings in premalignant CCA, pathology-proven cases of Bil-IN and IPNB at Chulabhorn Hospital were analyzed. Demographics, locations of lesions, imaging characteristics of both Bil-IN and IPNB were assessed, compared, and described.

RESULTS

Twenty-one premalignant lesions, 13 Bil-INs and 8 IPNBs, from 18 patients were included. Both Bil-IN and IPNB lesions were found more commonly at the right than left intrahepatic ducts (66.7% vs. 33.3%), and had more peripheral than central locations (85.7% vs. 14.3%). On US, Bil-IN commonly presented as focal bile duct dilatation (76.9%), whereas IPNB was more variable with hyperechoic nodules (37.5%), focal bile duct dilatation (37.5%), and diffuse bile duct dilatation with intraductal nodules (25%). On MRI, focal bile duct dilatation and nonfunctioning bile excretion are the most sensitive findings with sensitivities in the range of 84.6% to 100%. The presence of intraductal nodules and connection to the biliary system are findings that were significantly different between IPNB and Bil-IN, 62.5% versus 7.7% (p = 0.014) and 75% versus 15.4% (p = 0.018), respectively.

CONCLUSIONS

Premalignant lesions of CCA, including Bil-IN and IPNB, have different imaging presentations. Knowledge of imaging presentations may improve early detection and increase confidence in diagnosis.

Premalignant Lesions of the Biliary Tract

Although the most common presentation of biliary disorder in North America is secondary to gallstone disease, an awareness of benign biliary cystic neoplasms is important because of the risk of malignant transformation. The incidence of premalignant cystic neoplasms of the bile duct is not well characterized and they often are detected incidentally for suspicion of other abdominal disorders. This article describes the 4 most common premalignant biliary cystic neoplasms: biliary mucinous cystic neoplasms, intraductal papillary mucinous neoplasms of the bile duct, intraductal tubular papillary neoplasms of the bile duct, and choledochal cysts.

Uncommon Intraluminal Tumors of the Gallbladder and Biliary Tract: Spectrum of Imaging Appearances

Intraluminal pathologic conditions of the bile ducts and gallbladder are common, most frequently consisting of calculi and adenocarcinoma. In recent years, intraductal papillary neoplasm of the bile ducts (IPN-B), which is analogous to intraductal papillary mucinous neoplasm of the pancreas, has been recognized as a distinct pathologic entity and a precursor lesion to adenocarcinoma of the bile ducts. Intraductal tubulopapillary neoplasm (ITPN) of the bile duct was subsequently described as a distinct pathologic entity. With increased awareness and advances in imaging techniques, these lesions are diagnosed with increased frequency at preoperative imaging. A similar neoplasm in the gallbladder is referred to as intracholecystic papillary neoplasm. These lesions are often diagnosed at a preinvasive stage and have a better prognosis than invasive cholangiocarcinoma when treated with curative resection, underscoring the importance of an accurate imaging diagnosis. The most common causes of polypoid lesions of the gallbladder are cholesterol polyps and adenomyomatosis. These lesions need to be differentiated from the less common but clinically important adenocarcinoma of the gallbladder. Imaging is crucial to identify polyps that are at high risk for malignancy so that the appropriate management choice between imaging follow-up and cholecystectomy can be made by the treating physicians. Other less common gallbladder tumors, such as gallbladder adenomas, lymphoma, and metastases to the gallbladder, can manifest as intraluminal tumors; and awareness of these lesions is also important. In this article, the recent literature is reviewed; and the imaging appearances, histopathologic findings, and management of uncommon intraluminal tumors of the bile ducts and gallbladder and their mimics are discussed. ^©RSNA, 2019.

PBRM1 loss is a late event during the development of cholangiocarcinoma

AIMS

Somatic mutations in genes encoding chromatin remodellers have been reported recently in several cancer types, including approximately half of cholangiocarcinomas. One of the most commonly mutated chromatin remodellers in cholangiocarcinoma is the Polybromo-1 (PBRM1) gene located on chromosome 3p21, which encodes a subunit of the SWI/SNF complex. The aim of this study was to determine the timing of PBRM1 mutations in biliary carcinogenesis.

METHODS AND RESULTS

In order to accomplish this goal, we used immunohistochemistry to assess PBRM1 protein expression in a series of precursor lesions and invasive biliary carcinomas. Previous studies have correlated loss of protein expression on immunohistochemistry with inactivating mutations in this tumour suppressor gene. We found that PBRM1 loss occurred in approximately 26% of invasive cancers, but PBRM1 expression was retained in all biliary intra-epithelial neoplasia (BilIN) specimens, including 25 intrahepatic BilINs and 19 gallbladder BilINs.

CONCLUSIONS

These findings indicate that PBRM1 mutation (and resultant loss of expression) is a late event during biliary carcinogenesis. In addition, we confirm a lack of prognostic significance of PBRM1 status in invasive intrahepatic cholangiocarcinoma. This study provides important insights into the basic mechanisms of chromatin remodelling genes in carcinogenesis.

Updates on Precancerous Lesions of the Biliary Tract: Biliary Precancerous Lesion

Precursor lesions of invasive adenocarcinoma of the bile duct (cholangiocarcinoma) have been increasingly recognized during the past decade because of the results of multiple studies on the carcinogenesis of cholangiocarcinoma, technologic advancements in diagnostic imaging modalities, and an increase in the volume of elective procedures. The two main precursor lesions of cholangiocarcinoma that have evolved are biliary intraepithelial neoplasia and intraductal papillary neoplasm of the bile duct. These lesions demonstrate histomorphologic similarities to pancreatic intraepithelial neoplasia and intraductal papillary mucinous neoplasm of the pancreas, respectively, whereas mechanisms of carcinogenesis and risk of progressive disease appear distinct. An enhanced understanding of the clinical presentation and pathologic features of precursor lesions of the biliary tract and use of the correct terminology will facilitate efficient communication between surgeons, oncologists, and pathologists and improve quality of patient care.

Intracholecystic papillary-tubular neoplasm in a patient with choledochal cyst: a link between choledochal cyst and gallbladder cancer?

BACKGROUND

Intracholecystic papillary-tubular neoplasms are rare precursor lesions of gallbladder cancer. They were proposed as a separate pathologic entity in 2012 by Adsay et al. for the unification of a variety of mass-forming precursor lesions including papillary adenomas, tubulopapillary adenomas, intestinal adenomas, and others. They are considered homologous to intrapapillary mucinous neoplasms of the pancreas and intrabiliary papillary neoplasms of the common bile duct. In contrast with the commoner flat-type precursor gallbladder cancer lesions, they follow a more indolent clinical course and probably different genetic pathways to carcinogenesis. They are largely uninvestigated with only a handful of studies providing biological and clinical information. Choledochal cysts are dilation of the common bile duct. Diagnosis is usually established during childhood, and only a minority of patients are diagnosed at adulthood. They are of major clinical importance as they are known predisposing factors for biliary carcinogenesis.

CASE PRESENTATION

The current report describes a patient with a simultaneous diagnosis of choledochal cyst and intracholecystic papillary-tubular neoplasm. The patient underwent excision of the extrahepatic biliary tree for a Todani I choledochal cyst, and histological examination of the specimen revealed an intracholecystic papillary-tubular neoplasm of the gallbladder. Authors describe diagnostic and clinical course of the patient alongside clinical and biological characteristics of these rare lesions.

CONCLUSIONS

To the best of our knowledge, this is the first report of a patient with a simultaneous diagnosis of choledochal cyst and intracholecystic papillary-tubular neoplasm. Those rare lesions shed light on different forms of gallbladder cancer carcinogenesis and its relationship with choledochal cysts and cholestasis.