Intrahepatic cholangiocarcinoma with predominant "ductal plate malformation" pattern: a new subtype

Classification of intrahepatic cholangiocarcinoma

Cholangiocarcinoma is a heterogenous malignancy with various classifications based on location, morphological features, histological features, and actionable genetic mutations. Intrahepatic cholangiocarcinoma (ICC), which arises in and proximal to second order bile ducts, is the second most common primary liver malignancy after hepatocellular carcinoma. In this review, we will discuss ICC risk factors, precursor lesions, various growth, anatomic, morphologic, and histologic classifications, rare variants, and differential diagnoses.

Cholangiolocarcinoma with Ductal Plate Malformation Pattern: A 6-Year Follow-Up

INTRODUCTION

Cholangiolocarcinoma (CLC) with ductal plate malformation (DPM) is a rare primary liver cancer originating from the canals of Hering. It often exhibits intermediate behavior between hepatocellular carcinoma and intrahepatic cholangiocarcinoma. Diagnosing CLC with DPM is challenging due to overlapping imaging features with other liver malignancies.

CASE PRESENTATION

An 82-year-old man under surveillance for bladder cancer was incidentally found to have a liver nodule in segment 8. Over 6 years, the lesion grew from 10 mm to 41 mm and showed dynamic changes on imaging. Despite two inconclusive biopsies, a diagnosis of CLC with DPM was confirmed after a third biopsy and consultation with a specialized institution. The patient underwent a right hepatectomy, and pathological examination confirmed CLC with DPM. No evidence of recurrence was observed 19 months post-surgery.

CONCLUSIONS

This case underscores the importance of long-term follow-up and a multidisciplinary approach in managing rare hepatic malignancies. The clinical course provides valuable insights into the progression of CLC with DPM and may aid in diagnosing similar challenging cases.

Prognostic implications of tumor histology and microenvironment in surgically resected intrahepatic cholangiocarcinoma: a single institutional experience

Intrahepatic cholangiocarcinoma (ICC) is a highly aggressive malignant neoplasm. Certain histologic features and the tumor microenvironment may impact disease progression. We aim to characterize the clinicopathologic features of ICC to identify prognostic factors. A total of 50 surgically resected ICC (partial or transplant) cases were analyzed. The cohort included 26 men and 24 women with a median age of 62 years. Eighteen (36%) cases were multifocal ICC with a mean largest tumor size of 6.5 cm. Neoadjuvant and adjuvant chemotherapy was done in eight (16%) and 33 (66%) patients, respectively. Histologically, 42 (84%) were small duct type, seven (14%) large duct type, and one mixed (2%). Thirty (60%) cases showed lymphovascular invasion (LVI) and 11 (22%) with perineural invasion (PNI). Twenty-eight (56%) cases demonstrated dense intratumoral hyaline fibrosis and 18 (36%) with tumor necrosis, each ≥ 10% tumor volume. On follow-up, 35 (70%) patients died of disease after a median disease-specific survival (DSS) of 21 months. Univariate analysis revealed that hyaline fibrosis and adjuvant chemotherapy were associated with better DSS, while tumor size, multifocality, necrosis, and peritumoral neutrophil to lymphocyte ratio were associated with worse DSS. In contrast, age, sex, small vs. large duct types, LVI, and individual inflammatory cell counts were not significant prognostic factors. In summary, ICC is a heterogeneous malignancy with variable clinical courses associated with tumor burden, histology, and microenvironment. Targeting specific components within the tumor microenvironments may be a promising approach for treatment in the future.

Synchronous Hepatocellular and Intrahepatic Cholangiocellular Carcinoma With Predominant Ductal Plate Malformation Pattern. A Case Report and Review of the Literature

BACKGROUND

Synchronous occurrence of hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC) is extremely rare.

CASE

A 67-year-old male was admitted to the hospital with hemoperitoneum caused by a liver mass rupture and elevated serum liver enzymes. Abdominal magnetic resonance imaging revealed a solid mass, with 38 mm in maximum diameter, located in the fifth/sixth segments of the liver, suggesting an HCC. Emergency surgery was performed and a second liver mass in the fourth segment was identified intraoperatively, with 20 mm in maximum diameter. Hepatic resection of the affected segments was performed with free resection margins. Histopathological examination revealed the synchronous occurrence of HCC and ICC with a predominant ductal plate malformation pattern. The patient is still alive at 41 months after its first surgery.

CONCLUSIONS

In patients with HCC, a proper intraoperative assessment is indicated, in addition to imaging investigations, to detect synchronous lesions that can change the therapeutic approach. This is the first case ever reported in the literature in which synchronous HCC and ICC with a predominant ductal plate malformation pattern were incidentally diagnosed in a patient with hemoperitoneum.

Histopathological growth pattern and vessel co-option in intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma (iCCA) exhibits different blood imaging features and prognosis depending on histology. To clarity histopathological growth patterns (HGPs) and vascularization processes of iCCA, we collected 145 surgical specimens and histologically classified them into large bile duct (LBD) (20 cases), small bile duct (SBD) (54), cholangiolocarcinoma (CLC) (35), combined SBD-CLC (cSBD-CLC) (26), and ductal plate malformation (DPM) (10) (sub)types. According to the invasive pattern at the interface between tumor and adjacent background liver, HGPs were classified into desmoplastic, pushing, and replacing HGPs. Desmoplastic HGP predominated in LBD type (55.5%), while replacing HGP was common in CLC (82.9%) and cSBD-CLC (84.6%) subtypes. Desmoplastic HGP reflected angiogenesis, while replacing HGP showed vessel co-option in addition to angiogenesis. By evaluating microvessel density (MVD) using vascular markers, ELTD1 identified vessel co-option and angiogenesis, and ELTD1-positive MVD at invasive margin in replacing HGP was significantly higher than those in desmoplastic and pushing HGPs. REDD1, an angiogenesis-related marker, demonstrated preferably higher MVD in the tumor center than in other areas. iCCA (sub)types and HGPs were closely related to vessel co-option and immune-related factors (lymphatic vessels, lymphocytes, and neutrophils). In conclusion, HGPs and vascular mechanisms characterize iCCA (sub)types and vessel co-option linked to the immune microenvironment.

Recent Advances in Pathology of Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICCA) is a malignant epithelial neoplasm characterized by biliary differentiation within the liver. ICCA is molecularly heterogeneous and exhibits a broad spectrum of histopathological features. It is a highly aggressive carcinoma with high mortality and poor survival rates. ICCAs are classified into two main subtypes: the small-duct type and large-duct types. These two tumor types have different cell origins and clinicopathological features. ICCAs are characterized by numerous molecular alterations, including mutations in KRAS, TP53, IDH1/2, ARID1A, BAP1, BRAF, SAMD4, and EGFR, and FGFR2 fusion. Two main molecular subtypes-inflammation and proliferation-have been proposed. Recent advances in high-throughput assays using next-generation sequencing have improved our understanding of ICCA pathogenesis and molecular genetics. The diagnosis of ICCA poses a significant challenge for pathologists because of its varied morphologies and phenotypes. Accurate diagnosis of ICCA is essential for effective patient management and prognostic determination. This article provides an updated overview of ICCA pathology, focusing particularly on molecular features, histological subtypes, and diagnostic approaches.

Combined Hepatocellular-Cholangiocarcinoma With Ductal Plate Malformation Pattern: A Case Report With Molecular Analysis

Combined hepatocellular-cholangiocarcinoma with a ductal plate malformation pattern is an extremely rare entity with unelucidated pathogenesis. We present the case of a 60-year-old male patient who underwent a sectionectomy for pre-operative diagnosis of hepatocellular carcinoma based on clinical and image findings. Gross examination of the specimen revealed a well-defined tumor with cystic change measuring 6.7 × 6.2 cm. Microscopically, the lesion had classical features of hepatocellular carcinoma and intrahepatic cholangiocarcinoma exhibited neoplastic glands with irregular-sized dilated lumens, resembling a ductal plate malformation. Postoperative diagnosis was combined hepatocellular-cholangiocarcinoma with ductal plate malformation pattern. Next-generation sequencing revealed genomic alteration in 15 genes: CDKN2A, CHD4, CYP2D6, ERBB3, KIR3DL1, KRAS, MDM2, PIM1, STAT6, TPMT amplification, FANCD2, FAT1, FLT4, RASA1, and TP53 point mutation. This is the first case report of molecular alteration in combined hepatocellular-cholangiocarcinoma with ductal plate malformation pattern.

Nestin may be a candidate marker for differential diagnosis between small duct type and large duct type intrahepatic cholangiocarcinomas

BACKGROUNDS/AIMS

Intrahepatic cholangiocarcinoma (iCCA) is subclassified into small and large duct types. These two subtypes show distinct differences in various clinicopathological features and possible cell origin and pathways of carcinogenesis, however, a differential diagnosis may be sometimes difficult. Given the type IV intermediate filament, Nestin, may be a candidate diagnostic marker for combined hepatocellular-cholangiocarcinoma (cHCC-CCA) and small duct type iCCAs, the significance of nestin as a differential diagnostic marker between small and large duct types of iCCAs was addressed in the present study.

METHODS

Nestin expression was immunohistochemically assessed in the sections from 36 patients with small duct-type iCCA, 30 with large duct-type iCCA, and 27 with extrahepatic cholangiocarcinoma (CCA). Nestin expression and its relationship with clinicopathological features and genetic alterations were investigated in small duct type iCCAs.

RESULTS

Nestin expression was detected in 17 small duct type iCCAs (47.2%), one large duct type iCCA (3.8%) and zero extrahepatic CCA. Nestin expression was significantly more frequent in the patients with small duct type iCCAs than in those with large duct type iCCA and extrahepatic CCA (p < 0.01). In 10 liver biopsies, all samples with nestin expression were small duct type iCCAs. Nestin-positive small duct type iCCAs were characterized by a higher histological grade, compared to Nestin-negative small duct type iCCAs (p < 0.01). Nestin-positive small duct type iCCAs tended to have 2 or more genetic alterations, but there was no statistic difference (p > 0.05).

CONCLUSION

Different nestin expression may reflect differences between small duct type iCCA and large duct type/extrahepatic CCA and may be a useful diagnostic marker for small duct type iCCAs.

Expert Consensus on Pathological Diagnosis of Intrahepatic Cholangiocarcinoma (2022 version)

Intrahepatic cholangiocarcinoma (iCCA) can originate from the large bile duct group (segment bile ducts and area bile ducts), small bile duct group (septal bile ducts and interlobular bile ducts), and terminal bile duct group (bile ductules and canals of Hering) of the intrahepatic biliary tree, which can be histopathological corresponding to large duct type iCCA, small duct type iCCA and iCCA with ductal plate malformation pattern, and cholangiolocarcinoma, respectively. The challenge in pathological diagnosis of above subtypes of iCCA falls in the distinction of cellular morphologies, tissue structures, growth patterns, invasive behaviors, immunophenotypes, molecular mutations, and surgical prognoses. For these reasons, this expert consensus provides nine recommendations as a reference for standardizing and refining the diagnosis of pathological subtypes of iCCA, mainly based on the 5th edition of the World Health Organization Classification of Tumours of the Digestive System.

Challenges in Diagnosing and Reporting Cholangiocarcinoma

Intrahepatic cholangiocarcinoma is a challenge to the practicing surgical pathologist for several reasons. It is rare in many parts of the world, and thus practical exposure may be limited. Related to the fact of its rarity is the fact that more common tumors which frequently metastasize to the liver can be morphologically indistinguishable (eg, pancreatic ductal adenocarcinoma). Immunohistochemical testing is generally non-contributory in this context. Other difficulties arise from the protean morphologic manifestations of cholangiocarcinoma (ie, small duct vs. large duct) and the existence of combined cholangiocarcinoma and hepatocellular carcinoma. These, and other issues of concern to the practicing diagnostic pathologist are discussed herein.

Bile duct adenoma and small-sized small duct type intrahepatic cholangiocarcinoma show distinct differences in genetic alterations, expression of IMP3 and EZH2 and stromal and inflammatory components

AIMS

Given that bile duct adenoma was significantly more prevalent in the liver with small duct type intrahepatic cholangiocarcinoma (small duct iCCA), compared to other primary liver carcinomas, we examined the possibility of bile duct adenoma as a precursor of small duct iCCA by analysing genetic alterations and other features in bile duct adenomas.

METHODS AND RESULTS

Subjects included 33 bile duct adenomas and 17 small-sized (up to 2 cm in diameter) small duct iCCAs. Genetic alterations were examined by direct sequencing for hot-spot regions and immunohistochemical staining. The expression of p16^INK4a , EZH2 and IMP3 and stromal and inflammatory components were also examined. Genetic alterations examined including BRAF were not detected in bile duct adenomas, whereas genetic alterations of p53 (47%), ARID1A (41%), PBRM1 (12%), MTAP (12%), IDH1 (6%), KRAS (6%) and TERT promoter (6%) were detected in 16 small-sized small duct iCCA (94%) (P < 0.01). The expression of IMP3 and EZH2 was not detected in bile duct adenomas, whereas it was detected in most small duct iCCA (94%) (P < 0.01). Immature stroma and neutrophilic infiltration were significantly more prevalent in small duct iCCA, compared to bile duct adenoma (P < 0.01).

CONCLUSION

Bile duct adenomas and small-sized small duct iCCAs show distinct differences in genetic alterations, expression of IMP3 and EZH2 and stromal and inflammatory components. There was no evidence suggesting that bile duct adenoma is a precursor of small duct iCCA. Immunohistochemical staining for IMP3, EZH2, p53, ARID1A and MTAP may be useful for differential diagnosis between bile duct adenomas and small duct iCCAs.

Rare histotypes of epithelial biliary tract tumors: A literature review

Adenocarcinoma represents the most frequent biliary tract cancer. However, other rare histotypes can be found in the biliary tract, such as cholangiolocellular carcinoma, cholangiocarcinoma with ductal plate malformation pattern, adenosquamous carcinoma, mucinous carcinoma, signet ring cell carcinoma, clear cell carcinoma, mucoepidermoid carcinoma, lymphoepithelioma-like carcinoma, and sarcomatous cholangiocarcinoma. These cancer types account for less than 10 % of all the already rare biliary tract tumors. Yet, they represent a relevant issue in everyday clinical practice, given the lack of therapeutic recommendations and the overall scarcity of data, mainly deriving from isolated small center-specific cohorts of patients.The shifts of such histotypes from the most common ones reflect genetic and molecular differences, determine changes in clinical aggressiveness, and suggest a possible variability in sensitivity to the standard treatments of biliary adenocarcinomas. The consistency and degree of these variables are still to be solidly demonstrated and investigated. Therefore, this paper aims to review the current literature concerning very infrequent and rare epithelial biliary tract cancers, focusing our attention on the clinical, molecular, and immunohistochemical features of these tumors.

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.

Pathological, molecular, and clinical characteristics of cholangiocarcinoma: A comprehensive review

Cholangiocarcinomas are a heterogeneous group of highly aggressive cancers that may arise anywhere within the biliary tree. There is a wide geographical variation with regards to its incidence, and risk-factor associations which may include liver fluke infection, primary sclerosing cholangitis, and hepatolithiasis amongst others. These tumours are classified into intrahepatic, perihilar and distal based on their anatomical location. Morphologically, intrahepatic cholangiocarcinomas are further sub-classified into small and large duct variants. Perihilar and distal cholangiocarcinomas are usually mucin-producing tubular adenocarcinomas. Cholangiocarcinomas develop through a multistep carcinogenesis and are preceded by dysplastic and in situ lesions. While clinical characteristics and management of these tumours have been extensively elucidated in literature, their ultra-structure and tumour biology remain relatively unknown. This review focuses on the current knowledge of pathological characteristics, molecular alterations of cholangiocarcinoma, and its precursor lesions (including biliary intraepithelial neoplasia, intraductal papillary neoplasms of the bile duct, intraductal tubulopapillary neoplasms and mucinous cystic neoplasm).

Genetic, Clinicopathological, and Radiological Features of Intrahepatic Cholangiocarcinoma with Ductal Plate Malformation Pattern

Background/Aims

Intrahepatic cholangiocarcinoma (iCCA) with a ductal plate malformation (DPM) pattern is a recently recognized rare variant. The genomic profile of iCCA with DPM pattern needs to be elucidated.

Methods

Cases of iCCA with DPM pattern were retrospectively reviewed based on the medical records, pathology slides, and magnetic resonance imaging (MRI) reports collected between 2010 to 2019 at a single center. Massive parallel sequencing was performed for >500 cancer-related genes.

Results

From a total of 175 iCCAs, five (2.9%) cases of iCCA with DPM pattern were identified. All cases were of the small duct type, and background liver revealed chronic B viral or alcoholic hepatitis. Three iCCAs with DPM pattern harbored MRI features favoring the diagnosis of hepatocellular carcinoma, whereas nonspecific imaging features were observed in two cases. All patients were alive without recurrence during an average follow-up period of 57 months. Sequencing data revealed 64 mutated genes in the five cases, among which FGFR2 and PTPRT were most frequently mutated (three cases each) including an FGFR2-TNC fusion in one case. Mutations in ARID1A and CDKN2A were found in two cases, and mutations in TP53, BAP1, ATM, NF1, and STK11 were observed in one case each. No IDH1, KRAS, or PBRM1 mutations were found.

Conclusions

iCCAs with DPM pattern have different clinico-radio-pathologic and genetic characteristics compared to conventional iCCAs. Moreover, FGFR2 and ARID1A variants were identified. Altogether, these findings further suggest that iCCA with DPM pattern represents a specific subtype of small duct type iCCA.

Histopathological evidence of intrahepatic cholangiocarcinoma occurring in ductal plate malformation: A clinicopathologic study of 5 cases

Ductal plate malformations (DPM) arise from abnormal remodeling of the embryologic ductal plate of the liver. Malignant transformation of DPMs to intrahepatic cholangiocarcinoma (iCCA) has been reported in very rare instances but is viewed with some skepticism. We report the clinicopathological findings in five cases of iCCA, occurring in liver with DPM-like features. All tumors were less than 5 cm, often presented as stage T1a tumors. Histologically, a typical tumor showed a vague multinodular architecture with larger, irregular, tortuous glandular structures with microcystic dilation, intraluminal fibroepithelial projection, and bridge/island formation. The tumor cells were relatively small, bland, and without obvious pleomorphism. Interestingly, DPM presented as a histopathological transition sequence of definitively benign to biliary intraepithelial neoplasia (bilIN), then finally to iCCA. A complete pushing border, with entrapped portal tracts at the edge of the main tumor, suggested a replacing growth pattern. There was gradually increased expression of Ki-67 and p53 in these transition phases from benign to bilIN then to iCCA with DPM-like features. The neoplastic epithelium exhibited immunoreactivity in EpCAM, MUC1, NCAM, and CK19. KRAS mutation was found in 2 of the 5 iCCA cases with DPM-like features. Multifocal DPMs or VMCs with bilIN were dispersed in the non-tumor liver parenchyma in 3 of the 5 cases. The neoplasm was interpreted as iCCA arising in DPM, which may have originated from small bile duct or hepatic precursor cells. More studies are needed to verify this scarce entity and its premalignant properties.

Inhibin-positive hepatic carcinoma: proposal for a solid-tubulocystic variant of intrahepatic cholangiocarcinoma

Inhibin-positive hepatic carcinoma is a rare primary liver neoplasm that resembles sex cord-stromal tumor and thyroid follicular tumors. The term "cholangioblastic variant of intrahepatic cholangiocarcinoma" has been proposed. This study describes the clinicopathologic, immunophenotypic, and molecular features of a small series (n = 6) of this rare tumor. Albumin in situ hybridization (ISH) and capture-based next-generation sequencing (NGS) were also performed. All tumors occurred in young women (mean age 32.5 years, range 19-44 years) as a solitary large mass (mean 15.8 cm, range 6.9-23.5 cm). All tumors showed a highly distinctive morphology with sheets and large nests of tumor cells alternating with tubular and cystic areas imparting a sex cord-like or thyroid follicle-like morphology. Cytologic atypia was mild, and mitotic activity was low. All cases were positive for inhibin, as well as pancytokeratin, CK7, CK19, and albumin ISH. Synaptophysin and chromogranin showed focal or patchy staining, whereas INSM1 was negative. Markers for hepatocellular differentiation, thyroid origin, and sex cord-stromal tumor were negative. There were no recurrent genomic changes based on capture-based NGS of ∼500 cancer genes. Recurrence and/or metastasis was seen in three (50%) cases (follow-up time range for all cases: 5 months to 2 years). In conclusion, this series describes the distinctive morphology, immunophenotypic features, and diffuse albumin staining in six cases of a rare inhibin-positive primary liver carcinoma that runs an aggressive course similar to intrahepatic cholangiocarcinoma. Genomic changes typical of cholangiocarcinoma or hepatocellular carcinoma were not identified, and there were no recurrent genetic abnormalities. We propose the term "solid-tubulocystic variant of intrahepatic cholangiocarcinoma" to reflect the spectrum of morphologic patterns observed in this tumor.

Cholangiocarcinoma

Liver cancer represents the third leading cause of cancer-related death worldwide. Cholangiocarcinoma (CCA) is the second most common type of liver cancer after hepatocellular carcinoma, accounting for 10-15% of all primary liver malignancies. Both the incidence and mortality of CCA have been steadily increasing during the last decade. Moreover, most CCAs are diagnosed at an advanced stage, when therapeutic options are very limited. CCA may arise from any tract of the biliary system and it is classified into intrahepatic, perihilar, and distal CCA, according to the anatomical site of origin. This topographical classification also reflects distinct genetic and histological features, risk factors, and clinical outcomes. This review focuses on histopathology of CCA, its differential diagnoses, and its diagnostic pitfalls.

Diversity in cell differentiation, histology, phenotype and vasculature of mass-forming intrahepatic cholangiocarcinomas

AIMS

Mass-forming intrahepatic cholangiocarcinomas (MF-iCCAs), involving small bile ducts, bile ductules or canals of Hering, remain treated as a single entity. We aimed to examine the diversity in histology, phenotype and tumour vasculature of MF-iCCAs.

METHODS AND RESULTS

Based on morphology and immunophenotype, we classified MF-iCCAs into small bile duct (SBD), cholangiolocarcinoma (CLC), ductal plate malformation (DPM) and hepatocellular carcinoma (HCC)-like subtypes. Genetic correlations among the histological subtypes were examined by multi-region tumour sequencing. Vasculatures and other clinicopathological features were compared among tumour groups with various proportions of the histological subtypes in 62 MF-iCCAs. Cases of pure SBD, CLC, DPM and HCC-like subtypes numbered 18 (29%), seven (11.3%), none (0%) and two (3%), respectively; the remaining 35 (56.4%) cases comprised several components. Genetic alterations, isocitrate dehydrogenase (IDH)1/2, KRAS, TP53, polybromo-1 (PBRM1) and BRCA1-associated protein 1 (BAP1), were shared among SBD, CLC, DPM and hepatoid components within a tumour. We uncovered distinct vascularisation mechanisms among SBD, CLC and DPM subtypes with a prominent vessel co-option in CLC tumours. iCCA with a DPM pattern had the highest vascular densities (mean microvascular density,140/mm² ; arterial vessel density, 18.3/mm² ). Increased CLC component was correlated with longer overall survival time (r = 0.44, P = 0.006). Pure SBD tumours had a lower 5-year overall survival rate compared with MF-iCCA with CLC pattern (30.5 versus 72.4%, P = 0.011).

CONCLUSIONS

MF-iCCAs comprise four histological subtypes. Given their sharing some driver gene alterations, indicating they can have a common cell origin, SBD, CLC and DPM subtypes, however, differ in cell differentiation, histology, phenotype or tumour vasculature.

Italian Clinical Practice Guidelines on Cholangiocarcinoma - Part I: Classification, diagnosis and staging

Cholangiocarcinoma (CCA) is the second most common primary liver cancer, characterized by a poor prognosis and resistance to chemotherapeutics. The progressive increase in CCA incidence and mortality registered worldwide in the last two decades and the need to clarify various aspects of clinical management have prompted the Italian Association for the Study of the Liver (AISF) to commission the drafting of dedicated guidelines in collaboration with a group of Italian scientific societies. These guidelines have been formulated in accordance with the Italian National Institute of Health indications and developed by following the GRADE method and related advancements.

Bile duct adenoma may be a precursor lesion of small duct type intrahepatic cholangiocarcinoma

BACKGROUND/AIMS

Precursor lesions of small duct type intrahepatic cholangiocarcinoma (small duct iCCA) have not been clarified so far. We hypothesised that precursor lesions may be frequently distributed in the background liver of small duct iCCA.

METHODS AND RESULTS

We determined by histology the presence of bile duct adenomas and von Meyenburg complexes as candidate precursor lesions in the background liver of small duct iCCA, with other primary liver carcinomas as control. Subjects included 28 patients with small duct iCCA, 29 with large duct iCCAs, 60 with combined hepatocellular-cholangiocarcinoma (Comb) and 40 with hepatocellular carcinoma (HCC). The prevalence of bile duct adenomas in the background liver was significantly higher in small duct iCCA (35.7%) compared to other primary liver carcinomas (Comb, 4.9%; 10%, HCC) (P < 0.01). The prevalence of bile duct adenomas was significantly associated with the presence of von Meyenburg complexes and ductal plate malformation-like patterns in small duct iCCAs and Combs. Von Meyenburg complexes were detected in 11 small duct iCCA (39.3%), five large duct iCCAs (17.2%), 10 Comb (16.4%) and 13 HCC (33.3%), respectively (P > 0.05). Small duct iCCAs showed altered expression of ARID1A (46.4%), p53 (39.3%), PBRM1 (14.3%), IMP3 (85.7%) and EZH2 (82.1%), whereas these markers were negative in bile duct adenomas.

CONCLUSION

Bile duct adenomas may be precursor lesions of small duct iCCAs. Alteration of ARID1A, p53 or PBRM1 may be involved in the carcinogenesis of small duct iCCAs.

Cholangiolocellular Carcinoma With "Ductal Plate Malformation" Pattern May Be Characterized by ARID1A Genetic Alterations

Cholangiolocellular carcinoma (CLC) is a unique subtype of primary liver carcinoma, which sometimes coexists with hepatocellular carcinoma (HCC), cholangiocarcinoma and combined hepatocellular-cholangiocarcinoma (cHCC-CCA). "Ductal plate malformation" (DPM)-pattern of primary liver carcinoma, which resembles biliary lesions in Caroli disease and von Meyenburg complex, is sometimes associated with CLC. We examined genetic alterations of hTERT promoter (hTERT), IDH1 or 2 (IDH1/2), KRAS, ARID1A, PBRM1, ARID2, BAP1, p53 and their association with histologic features such as proportion of CLC and DPM-pattern in 77 patients with primary liver carcinoma diagnosed as cHCC-CCA or CLC. Primary liver carcinomas were histologically subdivided into 29 CLC-predominant (CLC component >80%), 31 with CLC (5% to 80%) and 17 without CLC (<5%). CLC-predominant group was characterized by older age, male-predominant and smaller tumor size. Genetic alterations were detected in hTERT (25%), ARID1A (21%), PBRM1 (20%), ARID2 (3%), BAP1 (1%), p53 (46%), KRAS (5%), and IDH1/2 (8%). ARID1A alteration was more frequent in CLC-predominant group, compared with other groups (P<0.05) and was correlated with the degree of DPM-pattern (P<0.01). Alterations of hTERT and p53 were less frequent in CLC-predominant group compared with "with CLC group" (P<0.05). hTERT mutation was less frequent in carcinomas with DPM-pattern (P<0.01). PBRM1 alteration was more frequent in CLC with focal HCC subgroup and without CLC group compared with other groups (P<0.05). CLC may be a distinct subgroup of primary liver carcinoma, which is different from cHCC-CCA, based on clinicopathologic and genetic alterations. ARID1A alterations may characterize CLC with DPM-pattern and could be a diagnostic immunohistochemical marker for small CLCs with DPM-pattern.

Cholangiolar pattern and albumin in situ hybridisation enable a diagnosis of intrahepatic cholangiocarcinoma

AIMS

The histological distinction of intrahepatic cholangiocarcinoma (ICC) from metastatic adenocarcinoma remains a challenge. The primary goal was to evaluate the diagnostic value of morphology and albumin expression in the diagnosis of ICC.

METHODS

We evaluated morphological patterns in 120 ICCs and 677 non-hepatic adenocarcinomas and performed in situ hybridisation (ISH) stain for albumin in the former cohort (retrospective cohort). We also identified 119 samples from primary and metastatic lesions, the validation cohort, in which albumin ISH was performed as part of the diagnostic workup. Targeted sequencing was performed on selected cases. We also mined existing expression profiling data including cases from The Cancer Genome Atlas (TCGA) (41 760 unique samples).

RESULTS

In the retrospective cohort, 45% of ICCs and <1% of non-hepatic adenocarcinomas showed a cholangiolar pattern; albumin ISH was positive in 93% of ICCs with significant intratumorous heterogeneity. In the validation cohort, 29% of ICCs showed a cholangiolar pattern and 88% expressed albumin, while all metastatic non-hepatic neoplasms were negative (n=37) (sensitivity 88% and specificity 100%). Targetable genetic alterations (IDH mutations and FGFR2 fusions) were identified in 31% of ICCs (10 of 32). An analysis of the TCGA data validated the specificity of the albumin assay.

CONCLUSIONS

The cholangiolar pattern and albumin RNA ISH distinguishes ICC from metastatic adenocarcinoma with high specificity. Given the high prevalence of targetable mutations in ICC, albumin RNA ISH is an essential component in the workup of tumours of uncertain origin. A specific diagnosis of ICC could trigger molecular testing and uncover targetable genetic alterations.

Distinct histomorphological features are associated with IDH1 mutation in intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma has known histological heterogeneity. Mutations in IDH1 (mIDH1) define a molecular subclass of intrahepatic cholangiocarcinoma and IDH-targeted therapies are in development. Characterizing mIDH1 ICC histomorphology is of clinical interest for efficient identification. Resected ICCs with targeted next-generation sequencing by MSK-IMPACT were selected. Clinical data were obtained. By slide review, blinded to IDH status, data were collected for histology type, mucin production, necrosis, fibrosis, cytoplasm cell shape (low cuboidal, plump cuboidal/polygonal, and columnar), and architectural pattern (anastomosing, tubular, compact tubular, and solid). A tumor was considered architecturally heterogeneous if no dominant pattern represented ≥75% of the tumor. Parameters were compared between mIDH1and IDH wild-type controls. In the examined cohort (113 ICC: 29 mIDH1 and 84 IDH wild-type), all IDH1-mutant tumors were of small duct-type histology, thus analysis was limited to 101 small duct-type tumors. mIDH1cases were more likely to have plump cuboidal/polygonal shape (P = .014) and geographic-type fibrosis (P = .005), while IDH1 wild-type were more likely to have low cuboidal shape (P = .005). Both groups were predominantly architecturally heterogeneous with no significant difference in the distribution of architectural patterns. Plump cuboidal/polygonal cell shape and a geographic-type pattern of intra-tumoral fibrosis are more often seen in mIDH1compared to IDH wild-type tumors; however, IDH1 mutation is not associated with a distinct histoarchitectural pattern.

Histopathological evidence of neoplastic progression of von Meyenburg complex to intrahepatic cholangiocarcinoma

Von Meyenburg complex (VMC) is generally thought to be benign, although its preneoplastic potential for intrahepatic cholangiocarcinoma (iCC) has been a subject of contention. We retrospectively reviewed 86 hepatectomy specimens with a diagnosis of iCC. Morphologically, an association between iCC and VMC was appreciated in 35% of cases that illustrated a gradual neoplastic progression from benign VMC to dysplasia and then to iCC. Among them, 24 cases had VMC lined by epithelial cells with low-grade biliary dysplasia and 13 with high-grade biliary dysplasia. VMC-associated iCCs were smaller in size and well to moderately differentiated, with features of anastomosing glandular architecture, ductal carcinoma in situ-like growth pattern, peritumoral lymphocytic infiltrate, central fibrous scar, and complete pushing border. They often presented as T1 tumors. In contrast, non-VMC-associated iCCs were moderately to poorly differentiated with solid, cribriform or papillary growth patterns. They likely exhibited necrosis, perineural invasion, positive surgical margin, lymphovascular invasion, and high T stage. Additionally, Ki67 and p53 immunostains support the continuing neoplastic evolution from benign VMC to dysplasia and then to iCC. VMC could become neoplastic, serving as an in situ carcinoma lesion to transform to iCC. The underlying molecular alteration and clinical implication of this neoplastic transformation deserves further investigation.

Integrative Genomic Analysis of Cholangiocarcinoma Identifies Distinct IDH-Mutant Molecular Profiles

Cholangiocarcinoma (CCA) is an aggressive malignancy of the bile ducts, with poor prognosis and limited treatment options. Here, we describe the integrated analysis of somatic mutations, RNA expression, copy number, and DNA methylation by The Cancer Genome Atlas, of a set of predominantly intrahepatic CCA cases, and propose a molecular classification scheme. We identified an IDH -mutant enriched subtype with distinct molecular features including low expression of chromatin modifiers, elevated expression of mitochondrial genes, and increased mitochondrial DNA copy number. Leveraging the multi-platform data, we observed that ARID1A exhibited DNA hypermethylation and decreased expression in the IDH -mutant subtype. More broadly, we found that IDH mutations are associated with an expanded histological spectrum of liver tumors with molecular features that stratify with CCA. Our studies reveal insights into the molecular pathogenesis and heterogeneity of cholangiocarcinoma and provide classification information of potential therapeutic significance.

Integrative Genomic Analysis of Cholangiocarcinoma Identifies Distinct IDH-Mutant Molecular Profiles

Cholangiocarcinoma (CCA) is an aggressive malignancy of the bile ducts, with poor prognosis and limited treatment options. Here, we describe the integrated analysis of somatic mutations, RNA expression, copy number, and DNA methylation by The Cancer Genome Atlas of a set of predominantly intrahepatic CCA cases and propose a molecular classification scheme. We identified an IDH mutant-enriched subtype with distinct molecular features including low expression of chromatin modifiers, elevated expression of mitochondrial genes, and increased mitochondrial DNA copy number. Leveraging the multi-platform data, we observed that ARID1A exhibited DNA hypermethylation and decreased expression in the IDH mutant subtype. More broadly, we found that IDH mutations are associated with an expanded histological spectrum of liver tumors with molecular features that stratify with CCA. Our studies reveal insights into the molecular pathogenesis and heterogeneity of cholangiocarcinoma and provide classification information of potential therapeutic significance.

Pathology of intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma (iCC) is a primary carcinoma of the liver with increasing significance and major pathogenic, clinical and therapeutic challenges. Classically, it arises from malignant transformation of cholangiocytes bordering small portal bile duct (BD) to second-order segmental large BDs. It has three major macroscopic growth pattern [mass-forming (MF), periductal infiltrative (PI), and intraductal growth (IG)] and histologically is a desmoplastic stroma-rich adenocarcinoma with cholangiocyte differentiation. Recent data pointed out noteworthy degree of heterogeneity in regards of their epidemiology and risk factors, pathological and molecular features, pathogenesis, clinical behaviors and treatment. Notably, several histological variants are described and can coexist within the same tumor. Several different cells of origin have also been depicted in a fraction of iCCs, amongst which malignant transformation of ductules, of hepatic stem/progenitor cells, of periductal glands or through oncogenic reprogramming of adult hepatocytes. A degree of pathological overlap with hepatocellular carcinoma (HCC) may be observed in a portion of iCC. A series of precursor lesions are today characterized and emphasize the existence of a multistep carcinogenesis process. Overall, these new data have brought up in proposal of new histological or molecular classifications, which could soon replace current anatomic-based classification and could have major impact on establishment of prognosis and on development of novel target treatment approaches.

Latest advances in the pathological understanding of cholangiocarcinomas

Cholangiocarcinomas (CCAs) are anatomically classified into intrahepatic, perihilar, and distal types. The gross pathological classification of intrahepatic CCAs divides them into mass-forming, periductal-infiltrating, and intraductal-growth types; and perihilar/distal CCAs into flat- and nodular-infiltrating and papillary types. Unique preinvasive lesions appear to precede individual gross types of CCA. Biliary intraepithelial neoplasia, a flat lesion, precedes periductal-, flat-, and nodular-infiltrating CCAs, whereas intraductal papillary neoplasm of the bile duct (IPNB) precedes the intraductal-growth and papillary type of CCAs. IPNBs are heterogeneous in their histological and pathological profiles along the biliary tree. Hepatobiliary cystadenomas/adenocarcinomas are reclassified as cystic IPNBs and hepatic mucinous cystic neoplasms. Peribiliary glands may participate in the development of CCAs. These latest findings present a new challenge for understanding the pathology of CCAs.

Human ductal plate and its derivatives express antigens of cholangiocellular, hepatocellular, hepatic stellate/progenitor cell, stem cell, and neuroendocrine lineages, and proliferative antigens

Molecular mechanisms of human ductal plate (DP) development and differentiation (DD) are unclear. The author immunohistochemically investigated expressions of cholangiocellular antigens (CEA, CA19-9, EMA, MUC1, MUC2, MUC5AC, MUC6, mucins, CK7, and CK19), hepatocellular antigens (HepPar1, AFP, CK8, and CK18), hepatic stellate/progenitor cell (HSC) antigens or stem cell (SC) antigens (C-erbB2, CD56, chromogranin, synaptophysin, bcl2, NSE, NCAM, KIT, and PDGFRA), and proliferating antigen (Ki67) in 32 human fetal livers (HFL). The DD of human intrahepatic bile duct (IBD) could be categorized into four stages: DP, remodeling DP, remodeled DP, and immature IBD. All the molecules examined were expressed in the DP and DP derivatives. These results suggest that human DP or DP derivatives have capacities to differentiate into cholangiocellular, hepatocellular, HSC, SC, and neuroendocrine lineages. The data also suggest that NCAM, KIT/SC factor-signaling, NSE, HGF/MET signaling, PDGFa/PDGFRA signaling, chromogranin, synaptophysin, and CD56 play important roles in DD of DP and biliary cells of HFL. DP, DP derivatives, and IBD in HFL have proliferative capacity.

Pathologic classification of cholangiocarcinoma: New concepts

Herein, we propose a new pathologic classification of cholangiocarcinoma (CCA) based on recent progress in studies of preinvasive CCA lesions and the relationship of CCA to hepatic progenitor cells, as well as a new concept with respect to the pathologic similarities between biliary and pancreatic neoplasms. Depending on anatomical location, CCA is classifiable as intrahepatic (iCCA), perihilar (pCCA), and distal CCA (dCCA). iCCA is classifiable as the conventional type and the bile ductular type, whereas pCCA and dCCA mainly present as conventional adenocarcinoma. In addition, these three CCAs may present as the intraductal neoplasm type or rare variants. Bile ductular CCA resembles proliferating bile ductules and expressing hepatic progenitor cell phenotypes. Four types of preinvasive lesions are proposed: flat, papillary, tubular lesion, and cystic lesion. These lesions are eventually followed by invasive CCA. Interestingly, these preinvasive lesions have pancreatic counterparts. This CCA classification may introduce a new field of CCA research.

Intrahepatic cholangiocarcinoma and cholangiolocellular carcinoma in cirrhosis and chronic viral hepatitis

Intrahepatic cholangiocarcinoma (ICC) is the second most common primary liver cancer. Cirrhosis and chronic viral hepatitis are known to be important risk factors for ICC, especially the mass-forming (MF) type of ICC at the periphery of the liver. Cholangiolocellular carcinoma (CoCC) is a rare type of primary liver cancer, which is thought to originate from hepatic progenitor or stem cells. CoCC often exhibits the similar MF type at the periphery of the liver, as ICC, and CoCC is also associated with cirrhosis or chronic viral hepatitis. Better survival rates after surgery have been reported for ICC patients with chronic viral hepatitis than for those without chronic viral hepatitis, although survival rates did not differ significantly in relation to cirrhosis. On the other hand, patients with CoCC had better surgical results than those with MF-type ICC. This review summarizes the clinical characteristics and surgical outcomes of ICC and CoCC associated with cirrhosis or chronic viral hepatitis.

Human fetal ductal plate revisited. I. ductal plate expresses NCAM, KIT, MET, PDGFRA, and neuroendocrine antigens (NSE, chromogranin, synaptophysin, and CD56)

BACKGROUND

The molecular mechanisms of ductal plate (DP) development and differentiation (DD) in human fetal livers (HFLs) are unclear.

MATERIALS AND METHODS

The author immunohistochemically investigated expressions of NCAM, KIT, KIT, PDGFRA, and neuroendocrine antigens in 32 HFLs.

RESULTS

The processes of human intrahepatic bile duct (IBD) DD could be categorized into four stages: DP, remodeling DP, remodeled DP, and mature IBD. NCAM was always expressed in DP and remodeling DP, but not in remodeled DP and mature IBD. The biliary elements were positive for cytokeratin (CK)7, 8, 18, and 19. The hepatoblasts were positive for CK8 and CD18, but negative for CK7 and CK19; however, periportal hepatoblasts showed biliary-type CKs (CK7 and CK19). NCAM was always expressed in DP and remodeling DP, but not in remodeled DP and mature IBD. KIT was occasionally (12/32 cases) expressed in DP and remodeling DP, but not in remodeled DP and mature IBD. NCAM expression was also seen in some hepatoblasts and hematopoietic cells and neurons. KIT was also expressed in some hepatoblasts, hematopoietic cells, and mast cells. MET and PDGFRA were strongly expressed in DP, remodeling DP, remodeled DP, and mature IBD. MET and PDGFRA were also strongly expressed in hepatoblasts and hematopoietic cells. MET and PDGFRA were not expressed in portal mesenchyme, portal veins, sinusoids, and hepatic veins. DP showed immunoreactive chromogranin, synaptophysin, neuron-specific enolase (NSE), and CD56. Expressions of chromogranin and CD56 were infrequently seen in remodeling DP. No expressions of these four neuroendocrine antigens were seen in remodeled DP and mature IBD. The nerve fibers were consistently positive for chromogranin, synaptophysin, NSE, and CD56 in the portal mesenchyme in the stages of remodeling DP, remodeled DP, and mature IBDs.

CONCLUSIONS

The data suggest that NCAM, KIT/stem cell factor-signaling, NSE, hepatocyte growth factor/MET signaling, PDGFα/PDGFRA signaling, chromogranin, synaptophysin, and CD56 play important roles in DD of biliary cells of HFL. They also suggest that the DP cells having neuroendocrine molecules give rise to hepatic stem/progenitor cells.

Long-term survival of patients with cholangiolocellular carcinoma after curative hepatectomy

BACKGROUND

Cholangiolocellular carcinoma (CoCC) has distinct pathological characteristics, and CoCC is considered to originate from hepatic progenitor or stem cells. However, the surgical outcome of CoCC has not been clarified in detail.

METHODS

We retrospectively studied 275 patients with intrahepatic cholangiocarcinoma (ICC) who underwent hepatectomy between 1990 and 2011. Surgical outcomes were compared between 29 patients with CoCC and 130 patients with mass-forming (MF) type ICC since all patients with CoCC showed MF type on macroscopic findings.

RESULTS

The number of patients with chronic liver disease was significantly higher in the CoCC group than in the ICC group. The number of patients with abnormal levels of CA19-9 was significantly lower in the CoCC group than in the ICC group. Portal vein invasion and intrahepatic metastasis were significantly lower in patients with CoCC group than in the ICC group. In the CoCC group, 15 of 28 patients survived for more than 5 years after curative surgery whereas 15 of 102 patients with ICC survived for more than 5 years after curative surgery. The 5-year survival rate was significantly higher in patients with CoCC (75 %) than in patients with ICC (33 %, p = 0.0005). Multivariate analysis showed CoCC, absence of portal vein invasion or hepatic vein invasion, and absence of intrahepatic metastasis to be significant independent prognostic factors for overall survival in patients with MF-type ICC and CoCC.

CONCLUSIONS

CoCC is rare, but patients with CoCC had special characteristics with favorable long-term survival due to its less invasive histopathologic characteristics.

Hilar cholangiocarcinoma is pathologically similar to pancreatic duct adenocarcinoma: suggestions of similar background and development

Routine experiences suggest that cholangiocarcinomas (CCAs) show different clinicopathological behaviors along the biliary tree, and hilar CCA apparently resembles pancreatic duct adenocarcinoma (PDAC). Herein, the backgrounds for these similarities were reviewed. While all cases of PDAC, hilar CCA, intrahepatic CCA (ICCA) and CCA components of combined hepatocellular-cholangiocarcinoma (cHC-CCA) were adenocarcinomas, micropapillary patterns and columnar carcinoma cells were common in PDAC and hilar CCA, and trabecular components and cuboidal carcinoma cells were common in ICCA and CCA components of cHC-CCA. Anterior gradient protein-2 and S100P were frequently expressed in perihilar CCA and PDAC, while neural cell adhesion molecule and luminal epithelial membrane antigen were common in CCA components of c-HC-CCA. Pdx1 and Hes1 were frequently and markedly expressed aberrantly in PDAC and perihilar CCA, although their expression was rare and mild in CCA components in cHC-CCA and ICCA. Hilar CCA showed a similar postoperative prognosis to PDAC but differed from ICCA and cHC-CCA. Taken together, hilar CCA may differ from ICCA and CCA components of cHC-CCA but have a similar development to PDAC. These similarities may be explained by the unique anatomical, embryological and reactive nature of the pancreatobiliary tract. Further studies of these intractable malignancies are warranted.

What are the precursor and early lesions of peripheral intrahepatic cholangiocarcinoma?

Cholangiocarcinoma (CC) is divided into distal, perihilar, and intrahepatic CCs (ICCS), and are further subdivided into large bile duct ICC and peripheral ICC. In distal and perihilar CC and large duct ICC, biliary intraepithelial neoplasm (BilIN) and intraductal papillary neoplasm (IPN) have been proposed as precursor lesions. Peripheral ICC, bile duct adenoma (BDA), biliary adenofibroma (BAF), and von Meyenburg complexes (VMCs) are reportedly followed by development of ICCs. Herein, we surveyed these candidate precursor lesions in the background liver of 37 cases of peripheral ICC and controls (perihilar CC, 34 cases; hepatocellular carcinoma, 34 cases and combined hepatocellular cholangiocarcinoma, 25 cases). In the background liver of peripheral ICC, BDA and BAF were not found, but there were not infrequently foci of BDA-like lesions and atypical bile duct lesions involving small bile ducts (32.4% and 10.8%, resp.). VMCs were equally found in peripheral CCs and also control CCs. In conclusion, BDA, BAF, and VMCs are a possible precursor lesion of a minority of peripheral CCs, and BDA-like lesions and atypical bile duct lesions involving small bile ducts may also be related to the development of peripheral ICC. Further pathologic studies on these lesions are warranted for analysis of development of peripheral ICCs.