Clinical and biological significance of precursor lesions of intrahepatic cholangiocarcinoma

Up-to-Date Pathologic Classification and Molecular Characteristics of Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (iCCA) is an aggressive primary liver malignancy with an increasing incidence worldwide. Recently, histopathologic classification of small duct type and large duct type iCCA has been introduced. Both these types of tumors exhibit differences in clinicopathological features, mutational profiles, and prognosis. Small duct type iCCA is composed of non-mucin-producing cuboidal cells, whereas large duct type iCCA is composed of mucin-producing columnar cells, reflecting different cells of origin. Large duct type iCCA shows more invasive growth and poorer prognosis than small duct type iCCA. The background liver of small duct type iCCA often shows chronic liver disease related to hepatitis B or C viral infection, or alcoholic or non-alcoholic fatty liver disease/steatohepatitis, in contrast to large duct type iCCA that is often related to hepatolithiasis and liver fluke infection. Cholangiolocarcinoma is a variant of small duct type iCCA composed of naïve-looking cuboidal cells forming cords or ductule-like structures, and shows better prognosis than the conventional small duct type. Fibrous tumor stroma, one of the characteristic features of iCCA, contains activated fibroblasts intermixed with innate and adaptive immune cells. The types of stroma (mature versus immature) are related to tumor behavior and prognosis. Low tumor-infiltrating lymphocyte density, KRAS alteration, and chromosomal instability are related to immune-suppressive tumor microenvironments with resistance to programmed death 1/ programmed death ligand 1 blockade. Data from recent large-scale exome analyses have revealed the heterogeneity in the molecular profiles of iCCA, showing that small duct type iCCA exhibit frequent BAP1, IDH1/2 hotspot mutations and FGFR2 fusion, in contrast to frequent mutations in KRAS, TP53, and SMAD4 observed in large duct type iCCA. Multi-omics analyses have proposed several molecular classifications of iCCA, including inflammation class and proliferation class. The inflammation class is enriched in inflammatory signaling pathways and expression of cytokines, while the proliferation class has activated oncogenic growth signaling pathways. Diverse pathologic features of iCCA and its associated multi-omics characteristics are currently under active investigation, thereby providing insights into precision therapeutics for patients with iCCA. This review provides the latest knowledge on the histopathologic classification of iCCA and its associated molecular features, ranging from tumor microenvironment to genomic and transcriptomic research.

Preneoplastic lesions in the liver: Molecular insights and relevance for clinical practice

Hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA) are the most frequent primary liver cancers, accounting for approximately 80% and 15%, respectively. HCC carcinogenesis occurs mostly in cirrhosis and is a complex multi-step process, from precancerous lesions (low-grade and high-grade dysplastic nodules) to progressed HCC. During the different stages of liver carcinogenesis, there is an accumulation of pathological, genetic and epigenetic changes leading to initiation, malignant transformation and finally tumour progression. In contrast, a small subset of HCC occurs in normal liver from the transformation of hepatocellular adenoma (HCA), a benign hepatocellular tumour. The recent molecular classification enables to stratify HCAs according to their risk of complication, in particular malignant transformation, associated with mutations in exon 3 of the catenin beta 1 (CTNNB1) gene. Cholangiocarcinoma (CCA) derives from the multistep malignant transformation of preneoplastic lesions, like biliary intraepithelial neoplasia (BilIN) and intraductal papillary neoplasm of the bile duct (IPNB), for which a pre-operative diagnosis remains difficult. Different genetic alterations are involved in BilIN and IPNB progression, leading to the development of tubular or intestinal adenocarcinoma. The aims of this review are to describe the main clinical and molecular features of preneoplastic lesions leading to the development of HCC and CCA, their implications in clinical practice and the perspectives for future research.

Precursor Lesions of Cholangiocarcinoma: A Clinicopathologic Review

Cholangiocarcinoma (CCA) develops through multistep carcinogenesis. During the past decades, 2 precursors have been proved to evolve to CCA. The 2 main precursor lesions of CCA are biliary intraepithelial neoplasia and intraductal papillary neoplasm of the bile duct. It is an interesting and relatively novel entity for the hepatobiliary surgeons, radiologists, oncologists, and pathologists. It worth being familiar with these 2 entities for better communication between pathologists, oncologists, and surgeons to improve the treatment and follow-up of these lesions, which can definitely decrease their evolvement to CCA as an aggressive, poor prognostic, and life-threatening cancer. In this narrative review, I collected and discussed all published studies about these 2 precursor lesions of CCA including radiologic, clinical, and pathological manifestation.

Biliary Intraepithelial Neoplasia in Non-biliary Cirrhosis-Report From 100 Explanted Livers: A Single Center Experience

Background:

Intrahepatic cholangiocarcinoma is a highly malignant tumor with a very short 5-year survival. Multistep carcinogenesis has been suggested as the main pathway for the development of this tumor. Main suggested precursors have been (1) biliary intraepithelial neoplasia (BilIN) and (2) intraductal papillary neoplasm of bile duct (IPNB). The former is flat and does not produce grossly and radiologically detectable mass lesion, but the latter produces grossly identifiable lesion.

Objectives:

The development of bile duct dysplasia (BilIN) in chronic biliary diseases has been investigated and proved, but the incidence of BilIN in non-biliary causes of cirrhosis such as hepatitis B and non-alcoholic steatohepatitis has very rarely been investigated. In this study, we have tried to find out the prevalence of BilIN in non-biliary cirrhosis.

Patients and Methods:

During the study period (2017-2018) in 100 explanted livers with the diagnosis of non-biliary cirrhosis, thorough sampling (at least 20 sections) was performed, and pathologic sections were studied for the presence of BilIN.

Results:

In the 100 studied livers with different diagnoses of non-biliary causes of cirrhosis, 31% of cases showed BilIN-1 and 2% of cases showed BiliIN-2. No case of BilIN-3 has been identified.

Discussion and Conclusions:

Non-biliary causes of cirrhosis should be considered as precursors of cholangiocarcinoma (BilIN); however, the incidence of this occurrence is low.

Early detection of intrahepatic cholangiocarcinoma

Cholangiocarcinoma (CC) is a malignant tumor which arises from the biliary epithelium and most cases represent adenocarcinoma. CC can be classified into intrahepatic CC (ICC), perihilar CC, and distal CC, based on the site of anatomic origin. The incidence of ICC is increasing in both Western and Eastern countries, while that of extrahepatic cholangiocarcinoma remains fairly stable. ICC infiltrates into adjacent nerves and lymphatic vessels, resulting in progressive disease with a poor prognosis; thus, early detection of ICC is critical for achieving better outcomes and providing better patient care. However, it is difficult for clinicians to detect an ICC, especially in its early stage. Different from hepatocellular carcinoma, the lack of surveillance system for the high-risk group of CC does not allow for a reliable screening examination. In this context, for early detection and diagnosis of ICC, radiologists need to know predisposing conditions that can lead to the development of ICC, such as chronic biliary or hepatic inflammation, primary sclerosing cholangitis, congenital biliary diseases, and other conditions. In this article, we discuss and illustrate the radiologic features of ICC with special attention to early disease stages and of predisposing conditions of ICC.

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.

Prevalence and Clinical Significance of Biliary Intraepithelial Neoplasia (BilIN) in Cholangiocarcinoma

Biliary intraepithelial neoplasia (BilIN) is the most common noninvasive precursor lesion which progresses to cholangiocarcinoma (CC) and is often found synchronously adjacent to the tumor or at the surgical resection margin. The aim of this study was to elucidate the prevalence and prognostic effect of BilIN on survival after resection for CC. We retrospectively analyzed the database of patients with CC who underwent surgery performed at our institution from 2010 to 2017. There were 142 patients who underwent surgery for CC. BilIN was detected in 42 patients (29.5%). On univariate analysis, extrahepatic CC (ExtraH CC) patients with BilIN lesions significantly showed better disease-free survival ( P = 0.05). Also, although not statistically significant, ExtraH CC patients with BilIN lesions revealed better overall survival (OS) ( P = 0.09). On multivariate analysis, presence of BilIN lesion, irrespective of location, was significantly associated with better disease-free survival (HR = 2.059, 95% confidence interval (CI): 1.057–4.432, P = 0.041) and OS (HR = 1.831, 95% CI: 1.149–3.534, P = 0.044) in ExtraH CC patients. The presence of BilIN lesions was not uncommon in CC patients and was significantly associated with better disease-free survival and OS in ExtraH CC patients. However, larger studies with longer follow-up are needed to accurately determine its clinical significance.

Molecular Pathogenesis of Cholangiocarcinoma

BACKGROUND

Cholangiocarcinomas are a heterogeneous group of malignancies arising from a number of cells of origin along the biliary tree. Although most cases in Western countries are sporadic, large population-based studies have identified a number of risk factors. This review summarises the evidence behind reported risk factors and current understanding of the molecular pathogenesis of cholangiocarcinoma, with a focus on inflammation and cholestasis as the driving forces in cholangiocarcinoma development.

RISK FACTORS FOR CHOLANGIOCARCINOGENESIS

Cholestatic liver diseases (e.g. primary sclerosing cholangitis and fibropolycystic liver diseases), liver cirrhosis, and biliary stone disease all increase the risk of cholangiocarcinoma. Certain bacterial, viral or parasitic infections such as hepatitis B and C and liver flukes also increase cholangiocarcinoma risk. Other risk factors include inflammatory disorders (such as inflammatory bowel disease and chronic pancreatitis), toxins (e.g. alcohol and tobacco), metabolic conditions (diabetes, obesity and non-alcoholic fatty liver disease) and a number of genetic disorders.

MOLECULAR PATHOGENESIS OF CHOLANGIOCARCINOMA

Regardless of aetiology, most risk factors cause chronic inflammation or cholestasis. Chronic inflammation leads to increased exposure of cholangiocytes to the inflammatory mediators interleukin-6, Tumour Necrosis Factor-ɑ, Cyclo-oxygenase-2 and Wnt, resulting in progressive mutations in tumour suppressor genes, proto-oncogenes and DNA mismatch-repair genes. Accumulating bile acids from cholestasis lead to reduced pH, increased apoptosis and activation of ERK1/2, Akt and NF-κB pathways that encourage cell proliferation, migration and survival. Other mediators upregulated in cholangiocarcinoma include Transforming Growth Factor-β, Vascular Endothelial Growth Factor, Hepatocyte Growth Factor and several microRNAs. Increased expression of the cell surface receptor c-Met, the glucose transporter GLUT-1 and the sodium iodide symporter lead to tumour growth, angiogenesis and cell migration. Stromal changes are also observed, resulting in alterations to the extracellular matrix composition and recruitment of fibroblasts and macrophages that create a microenvironment promoting cell survival, invasion and metastasis.

CONCLUSION

Regardless of aetiology, most risk factors for cholangiocarcinoma cause chronic inflammation and/or cholestasis, leading to the activation of common intracellular pathways that result in reactive cell proliferation, genetic/epigenetic mutations and cholangiocarcinogenesis. An understanding of the molecular pathogenesis of cholangiocarcinoma is vital when developing new diagnostic biomarkers and targeted therapies for this disease.

Long-term outcomes of patients with intraductal growth sub-type of intrahepatic cholangiocarcinoma

BACKGROUND

Intraductal-growth (IG) type of intrahepatic cholangiocarcinoma (ICC) may be associated with a favorable prognosis compared with mass-forming (MF) and periductal-infiltrating (PI) ICC.

METHODS

The clinico-pathological characteristics and long-term outcomes of 1206 patients undergoing liver resection for ICC were compared based on the ICC morphological classification.

RESULTS

Compared with MF patients, IG patients had a higher incidence of poor/un-differentiated tumor, lympho-vascular, and perineural invasion (poor/un-differentiated: MF, 18% vs. IG, 24%; lympho-vascular invasion: MF, 30% vs. IG, 35%; perineural invasion: MF, 17% vs. IG, 33%; all p > 0.05). The pattern of recurrence was different among MF patients (intrahepatic only: 63%; extrahepatic only: 22%; both intra- and extrahepatic: 16%) versus IG patients (intrahepatic only: 46%; extrahepatic: 25%; both intra- and extrahepatic: 29%) (p < 0.001). Moreover, while 78% of patients with MF had an early recurrence (<18 months from surgery), 59% of IG patients had and early recurrence (p = 0.039). On multivariable analysis, after controlling for competing risk factors, IG patients had a similar prognosis as MF patients (HR 0.90, p = 0.69).

CONCLUSION

While IG patients more frequently presented with more adverse pathological characteristics, the prognosis of IG patients was comparable with MF patients after controlling for all these adverse factors.

Intraductal Papillary Neoplasm of the Bile Duct: Clinical, Imaging, and Pathologic Features

OBJECTIVE

We outline the concept of intraductal papillary neoplasm of the bile duct (IPNB), discuss the morphologic features of IPNB and the differential diagnoses, and describe the radiologic approaches used in multidisciplinary management.

CONCLUSION

The concept of IPNB has been evolving. Because the imaging features of IPNB can be variable, different mimickers according to IPNB subtype can be considered. A multimodality approach is essential to obtain an optimal diagnosis and establish treatment plans.

Surgery is the preferred treatment for bile duct hamartomas

Bile duct hamartoma (BDH) is a rare liver disease with a rising incidence in recent years. A retrospective study on BDH patients between June 2007 and December 2015 was conducted. All the medical records, including clinical, imaging and pathological characteristics, were retrieved. Follow-up data were obtained by telephone communication. The majority of the patients had no symptoms and the laboratory tests were normal. The appearance on ultrasound examination was variable. The lesion exhibited low density on plain computed tomography and no enhancement in 4 cases, and inhomogeneous enhancement in 1 case. Magnetic resonance imaging examination revealed hypointensity on T1-weighted imaging (WI), hyperintensity on T2WI, no enhancement in 1 case, and enhancement in 4 cases. Two patients underwent magnetic resonance cholangiopancreatography due to jaundice and intrahepatic bile duct dilation. The preoperative diagnosis was liver cancer in 4 cases, hepatic hilar biliary obstruction in 1, chronic calculous cholecystitis in 1, suspected hepatic abscess in 1, and benign liver tumor in 2 cases. All the patients underwent surgery. Nest-like cell arrangements were observed in 2 patients, and in 1 patient the lesion transformed to intrahepatic cholangiocarcinoma, resulting in the patient's death 25 months after surgery. Thus, BDH may transform into a life-threatening cholangiocarcinoma and it should be surgically removed. Furthermore, the mechanism underlying carcinogenesis in BDH requires further investigation.