Intrahepatic cholangiocarcinoma: typical features, uncommon variants, and controversial related entities

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.

Tubulocystic Carcinoma of Bile Ducts: A Distinct Type of Cholangiocarcinoma Associated With Adenofibroma-type Lesions

A type of cholangiocarcinoma (CCA) characterized by peculiar histologic patterns and underlying adenofibromatous lesions has been reported in the literature mostly as individual case reports. This study aims to further clarify the defining characteristics of this spectrum of lesions. Clinicopathologic analysis of 8 biliary tumors with tubulocystic architecture arising in the background of adenofibroma-type lesions was performed. Three of these were also investigated with next-generation sequencing with a 174 genes panel. The patients were 5 males and 3 females, with a mean age of 64.6. All tumors were intrahepatic except for one perihilar that protruded into soft tissues. The mean size was 4.4 cm. At histology, all cases showed a peculiar and cytologically bland tubulocystic pattern that closely resembled tubulocystic-type kidney cancers, including back-to-back microcystic units that formed relatively demarcated nodules, and occurring in the background of adenofibromatous lesions. One case showed perineural invasion by otherwise deceptively benign-appearing microcystic structures, one had areas transitioning to intraductal tubulopapillary neoplasm, and 3 cases harbored more conventional small-duct CCA foci. In those 3 cases, both the tubulocystic and conventional CCA components were investigated by next-generation sequencing separately, and they shared the molecular alterations, including recurrent mutations in chromatin remodeling genes, such as ARID1A, BAP1, and PBRM1, and the actionable FGFR2-MCU fusion gene. In the limited follow-up, all but one were alive and free of disease after surgical resection. In conclusion, we described a distinct entity of CCA with specific histo-molecular features, for which we propose the designation of tubulocystic carcinoma of bile ducts.

An Immunohistochemical Analysis of Osteopontin and S100 Calcium-binding Protein P is Useful for Subclassifying Large- and Small-duct Type Intrahepatic Cholangiocarcinomas

Intrahepatic cholangiocarcinoma (iCCA) has been newly subclassified into two different subtypes: large-duct (LD) type and small-duct (SD) type. However, many cases are difficult to subclassify, and there is no consensus regarding subclassification criteria. LD type expresses the highly sensitive diagnostic marker S100 calcium-binding protein P (S100P), while SD type lacks sensitive markers. We identified osteopontin (OPN) as a highly sensitive marker for SD type. This study aimed to develop new subclassification criteria for LD-type and SD-type iCCA. We retrospectively investigated 74 patients with iCCA and subclassified them based on whole-section immunostaining of S100P and OPN. Of the 74 cases, 41 were subclassified as LD type, 32 as SD type, and one was indeterminate. Notably, all S100P-negative cases had OPN positivity. Seventy-three of the 74 cases (98.6%) were clearly and easily subclassified as LD or SD type using only these 2 markers. We also determined the value of immunohistochemistry in cases that were difficult to diagnose based on hematoxylin-eosin and Alcian blue-periodic acid-Schiff staining. Furthermore, we analyzed the clinicopathological characteristics and prognoses of these 2 subtypes. LD type was a poor prognostic factor on univariate analysis; it had significantly worse overall survival ( P = 0.007) and recurrence-free survival ( P < 0.001) than the SD type. In conclusion, we propose new subclassification criteria for iCCA based on immunostaining of S100P and OPN. These criteria may help pathologists to diagnose subtypes of iCCA, supporting future clinical trials and the development of medications for these 2 subtypes as distinct cancers.

NAC1 transcriptional activation of LDHA induces hepatitis B virus immune evasion leading to cirrhosis and hepatocellular carcinoma development

Our study aimed to elucidate the molecular mechanisms underlying NAC1 (nucleus accumbens associated 1) transcriptional regulation of LDHA and its role in HBV immune evasion, thus contributing to the development of cirrhosis and hepatocellular carcinoma (HCC). Utilizing public datasets, we performed differential gene expression and weighted gene co-expression network analysis (WGCNA) on HBV-induced cirrhosis/HCC data. We identified candidate genes by intersecting differentially expressed genes with co-expression modules. We validated these genes using the TCGA database, conducting survival analysis to pinpoint key genes affecting HBV-HCC prognosis. We also employed the TIMER database for immune cell infiltration data and analyzed correlations with identified key genes to uncover potential immune escape pathways. In vitro, we investigated the impact of NAC1 and LDHA on immune cell apoptosis and HBV immune evasion. In vivo, we confirmed these findings using an HBV-induced cirrhosis model. Bioinformatics analysis revealed 676 genes influenced by HBV infection, with 475 genes showing differential expression in HBV-HCC. NAC1 emerged as a key gene, potentially mediating HBV immune escape through LDHA transcriptional regulation. Experimental data demonstrated that NAC1 transcriptionally activates LDHA, promoting immune cell apoptosis and HBV immune evasion. Animal studies confirmed these findings, linking NAC1-mediated LDHA activation to cirrhosis and HCC development. NAC1, highly expressed in HBV-infected liver cells, likely drives HBV immune escape by activating LDHA expression, inhibiting CD8 + T cells, and promoting cirrhosis and HCC development.

Nucleolin lactylation contributes to intrahepatic cholangiocarcinoma pathogenesis via RNA splicing regulation of MADD

BACKGROUND & AIMS

Intrahepatic cholangiocarcinoma (iCCA) is a fatal malignancy of the biliary system. The lack of a detailed understanding of oncogenic signaling or global gene expression alterations has impeded clinical iCCA diagnosis and therapy. The role of protein lactylation, a newly unraveled post-translational modification that orchestrates gene expression, remains largely elusive in the pathogenesis of iCCA.

METHODS

Proteomics analysis of clinical iCCA specimens and adjacent tissues was performed to screen for proteins aberrantly lactylated in iCCA. Mass spectrometry, macromolecule interaction and cell behavioral studies were employed to identify the specific lactylation sites on the candidate protein(s) and to decipher the downstream mechanisms responsible for iCCA development, which were subsequently validated using a xenograft tumor model and clinical samples.

RESULTS

Nucleolin (NCL), the most abundant RNA-binding protein in the nucleolus, was identified as a functional lactylation target that correlates with iCCA occurrence and progression. NCL was lactylated predominantly at lysine 477 by the acyltransferase P300 in response to a hyperactivity of glycolysis, and promoted the proliferation and invasion of iCCA cells. Mechanistically, lactylated NCL bound to the primary transcript of MAP kinase-activating death domain protein (MADD) and led to efficient translation of MADD by circumventing alternative splicing that generates a premature termination codon. NCL lactylation, MADD translation and subsequent ERK activation promoted xenograft tumor growth and were associated with overall survival in patients with iCCA.

CONCLUSION

NCL is lactylated to upregulate MADD through an RNA splicing-dependent mechanism, which potentiates iCCA pathogenesis via the MAPK pathway. Our findings reveal a novel link between metabolic reprogramming and canonical tumor-initiating events, and uncover biomarkers that can potentially be used for prognostic evaluation or targeted treatment of iCCA.

IMPACT AND IMPLICATIONS

Intrahepatic cholangiocarcinoma (iCCA) is a highly aggressive liver malignancy with largely uncharacterized pathogenetic mechanisms. Herein, we demonstrated that glycolysis promotes P300-catalyzed lactylation of nucleolin, which upregulates MAP kinase-activating death domain protein (MADD) through precise mRNA splicing and activates ERK signaling to drive iCCA development. These findings unravel a novel link between metabolic rewiring and canonical oncogenic pathways, and reveal new biomarkers for prognostic assessment and targeting of clinical iCCA.

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.

Interobserver agreement of pathologic classification and grading of tumoral intraductal pre-invasive neoplasms of the bile duct

Current WHO terminology and recent publications have classified tumoral (grossly visible) intraductal pre-invasive neoplasms of bile duct (TIDN) into three categories: intraductal papillary neoplasm of bile duct (IPNB), intraductal papillary oncocytic neoplasm (IOPN), and intraductal tubulopapillary neoplasm (ITPN). A total of 227 cases of TIDN and related lesions ≥3 mm in height were examined by 10 biliary pathologists referring to these 3 categories and two pathologic gradings: two-tiered system (low- and high-grade dysplasia) and modified types 1 and 2 subclassification. Among them, IPNB was the most frequent (183 cases), followed by IOPN (28 cases), while ITPN was rare (2 cases), and interobserver agreement in this classification was "substantial" (κ-value, 0.657). The interobserver agreement of two-tiered grading system of TIDN was "slight" (κ-value, 0.201), while that of modified types 1 and 2 subclassification was "moderate" (κ-value, 0.515), and 42 % were of type 1, and 58 % were of type 2. Type 1 TIDN showed occasional stromal invasion (6.7 %), whereas type 2 TIDN was frequently associated with stromal invasion (49.6 %) (p < 0.01). In conclusion, the classification of TIDN into three categories and modified types 1 and 2 subclassification are a practically applicable classification and grading system for TIDN.

NIPBL::NACC1 Fusion Hepatic Carcinoma

Several reports describing a rare primary liver tumor with histologic features reminiscent of follicular thyroid neoplasms have been published under a variety of descriptive terms including thyroid-like, solid tubulocystic, and cholangioblastic cholangiocarcinoma. Although these tumors are considered to represent histologic variants, they lack classic features of cholangiocarcinoma and have unique characteristics, namely immunoreactivity for inhibin and NIPBL::NACC1 fusions. The purpose of this study is to present clinicopathologic and molecular data for a large series of these tumors to better understand their pathogenesis. We identified 11 hepatic tumors with these features. Immunohistochemical and NACC1 and NIPBL fluorescence in situ hybridization assays were performed on all cases. Four cases had available material for whole-genome sequencing (WGS) analysis. Most patients were adult women (mean age: 42 y) who presented with abdominal pain and large hepatic masses (mean size: 14 cm). Ten patients had no known liver disease. Of the patients with follow-up information, 3/9 (33%) pursued aggressive behavior. All tumors were composed of bland cuboidal cells with follicular and solid/trabecular growth patterns in various combinations, were immunoreactive for inhibin, showed albumin mRNA by in situ hybridization, and harbored the NIPBL::NACC1 fusion by fluorescence in situ hybridization. WGS corroborated the presence of the fusion in all 4 tested cases, high tumor mutational burden in 2 cases, and over 30 structural variants per case in 3 sequenced tumors. The cases lacked mutations typical of conventional intrahepatic cholangiocarcinoma. In this report, we describe the largest series of primary inhibin-positive hepatic neoplasms harboring a NIPBL::NACC1 fusion and the first WGS analysis of these tumors. We propose to name this neoplasm NIPBL:NACC1 fusion hepatic carcinoma.

Enteroblastic cholangiocarcinoma: An uncommon, underrecognized subtype of bile duct cancer

Enteroblastic carcinoma is clinically characterized by an elevated serum level of alpha-fetoprotein (AFP) and is histologically characterized by cancer cells with a clear cytoplasm and 'blastic' coarse chromatin. It sometimes has an element of hepatoid carcinoma; therefore, these two neoplasms are often regarded as sister entities. Although hepatoid carcinoma in the biliary tree has been reported, enteroblastic cholangiocarcinoma is extremely uncommon. In the present study, four cases of enteroblastic cholangiocarcinoma were examined. Tumors were located inside the liver (n = 2) or common bile duct (n = 2). The two intrahepatic cases had a history of primary sclerosing cholangitis, and serum AFP levels were elevated in both. One unresectable case was diagnosed by needle liver biopsy, while the remaining three underwent surgical resection. Histologically, all cases showed similar microscopic features. Cuboidal or polygonal cancer cells with the characteristic clear cytoplasm and subnuclear vacuoles were arranged in a papillary, micropapillary, tubular, or solid architecture. One case had an element of pancreatobiliary-type adenocarcinoma, while a hepatoid carcinoma element was not observed in any cases. All cases were positive for AFP, glypican 3, and SALL4, with SALL4 being the most widely expressed. Heppar-1 and arginase-1 were negative, except for one case, which was positive for Heppar-1. In conclusion, enteroblastic cholangiocarcinoma is an uncommon subtype of biliary tract malignancy. These cases may have been categorized as 'clear cell' cholangiocarcinoma. Although enteroblastic cholangiocarcinoma seems to occur more commonly in extrahepatic regions, including the gallbladder, it may also develop in the liver, particularly in patients with primary sclerosing cholangitis.

Precision therapy for intrahepatic cholangiocarcinoma: A case report on adjuvant treatment in a recurrent patient after surgery and literature review

A 37-year-old female patient was diagnosed with intrahepatic cholangiocarcinoma (ICC), with the lesion located in the right lobe of the liver. Despite radical resection, postoperative adjuvant chemotherapy and a combination of adjuvant chemotherapy and immunotherapy, the patient continued to experience multiple instances of intrahepatic tumor metastases. Furthermore, the patient exhibited significant adverse reactions to systemic chemotherapy and had poor treatment tolerance. Guidance from paraffin section fluorescence in situ hybridization gene sequencing was used to select a combination of immunotherapy and targeted therapy treatments with programmed cell death 1 (PD-1)/PD-1 ligand 1 antibody durvalumab and the targeted drug pemigatinib. The patient tolerated the treatment and has continued to survive for 28 months. According to imaging evaluations, the lesions continued to decrease, with some disappearing completely. The tumor marker carbohydrate antigen 19-9 remained normal for >9 weeks during the treatment. This report described the patient's treatment process in detail and briefly reviewed relevant literature on the treatment progress of postoperative patients with ICC.

Solid-Tubulocystic carcinoma: A new variant of intrahepatic cholangiocarcinoma

A new variant of intrahepatic cholangiocarcinoma (iCCA) has been recognized in recent years presenting predominantly as a large hepatic mass in young woman with the characteristic expression of inhibin by immunohistochemistry. This variant iCCA was originally termed as cholangioblastic variant of iCCA, and subsequently proposed to be renamed as inhibin-positive hepatic carcinoma or solid-tubulocystic variant of iCCA to better reflect its immunohistochemical profile or morphologic spectrum. The tumor histologically is composed of small to medium sized cells with scant to moderate amount of eosinophilic cytoplasm heterogeneously organized in solid, tubular, and cystic growth patterns. The tumor cells are positive for biliary markers, inhibin and albumin, and have a novel recurrent gene fusion, NIPBL::NACC1. Awareness of this new iCCA variant and its clinicopathologic features will aid in the diagnostic work-up and avoid confusion with other primary and metastatic hepatic neoplasms.

Pathological survey of precursor lesions in cholangiocarcinoma

BACKGROUND

To clarify the pathological significance of two precursors (high-grade biliary intraepithelial neoplasm [BilIN] and intraductal papillary neoplasm of bile duct [IPNB]) in cholangiocarcinomas (CCAs).

METHODS

Ninety-one cases of CCA (47 distal CCAs [dCCAs], 31 perihilar CCAs [pCCAs] and 13 intrahepatic CCAs of large duct type [LD-iCCAs]) were examined for their association with precursors. Neoplastic intraepithelial lesions without underlying infiltrating carcinoma in the surrounding mucosa of CCAs were considered to reflect high-grade BilIN. High-grade BilIN and IPNB were subdivided into gastric, biliary, intestinal and oncocytic subtypes, while CCAs were subdivided into gastrobiliary, intestinal and oncocytic subtypes. The postoperative overall survival (OS) was examined.

RESULTS

Fifty-four and 8 of 91 CCAs were associated with high-grade BilIN and IPNB, respectively, while these precursors were unidentifiable in the remaining CCAs. A majority of CCAs were of the gastrobiliary subtype, while the intestinal subtype was occasionally detected, and the oncocytic subtype was rare. CCAs with high-grade BilIN showed a similar postoperative OS to CCAs without precursors, while CCAs with IPNB showed a favorable postoperative OS compared to CCAs without precursors.

CONCLUSIONS

CCAs were frequently associated with precursors; high-grade BilIN may be a major precursor and IPNB a minor one. CCAs with IPNB showed a favorable postoperative OS compared to CCAs with high-grade BilIN.

Pemigatinib in Intrahepatic Cholangiocarcinoma: A Work in Progress

Cholangiocarcinoma (CCA) is the second most frequent primary liver cancer, following hepatocellular carcinoma (HCC). Progress in the molecular understanding of CCA has led to the development of several agents, including FGFR inhibitors, such as pemigatinib, whose approval has marked a new era in this hepatobiliary malignancy. However, a number of questions remain unanswered, including the development of secondary resistance and the role of combination therapies, including FGFR inhibitors. Herein, we specifically focus on the current challenges and future research directions of pemigatinib use in CCA patients.

Molecular Profile and Prognostic Value of BAP1 Mutations in Intrahepatic Cholangiocarcinoma: A Genomic Database Analysis

Background. Recent years have witnessed the advent of molecular profiling for intrahepatic cholangiocarcinoma (iCCA), and new techniques have led to the identification of several molecular alterations. Precision oncology approaches have been widely evaluated and are currently under assessment, as shown by the recent development of a wide range of agents targeting Fibroblast Growth Factor Receptor (FGFR) 2, Isocitrate Dehydrogenase 1 (IDH-1), and BRAF. However, several knowledge gaps persist in the understanding of the genomic landscape of this hepatobiliary malignancy. Methods. In the current study, we aimed to comprehensively analyze clinicopathological features of BAP1-mutated iCCA patients in public datasets to increase the current knowledge on the molecular and biological profile of iCCA. Results. The current database study, including 772 iCCAs, identified BAP1 mutations in 120 cases (15.7%). According to our analysis, no differences in terms of overall survival and relapse-free survival were observed between BAP1-mutated and BAP1 wild-type patients receiving radical surgery. In addition, IDH1, PBRM1, and ARID1A mutations were the most commonly co-altered genes in BAP1-mutated iCCAs. Conclusions. The genomic characterization of iCCA is destined to become increasingly important, and more efforts aimed to implement iCCA genomics analysis are warranted.