Integrated analyses of the genetic and clinicopathological features of cholangiolocarcinoma: cholangiolocarcinoma may be characterized by mismatch-repair deficiency.

Cholangiolocarcinoma (CLC) is a primary liver carcinoma that resembles the canals of Hering and that has been reported to be associated with stem cell features. Due to its rarity, the nature of CLC remains unclear, and its pathological classification remains controversial. To clarify the positioning of CLC in primary liver cancers and identify characteristics that could distinguish CLC from other liver cancers, we performed integrated analyses using whole-exome sequencing (WES), immunohistochemistry, and a retrospective review of clinical information on eight CLC cases and two cases of recurrent CLC. WES demonstrated that CLC includes IDH1 and BAP1 mutations, which are characteristic of intrahepatic cholangiocarcinoma (iCCA). A mutational signature analysis showed a pattern similar to that of iCCA, which was different from that of hepatocellular carcinoma (HCC). CLC cells, including CK7, CK19, and EpCAM, were positive for cholangiocytic differentiation markers. However, the hepatocytic differentiation marker AFP and stem cell marker SALL4 were completely negative. The immunostaining patterns of CLC with CD56 and epithelial membrane antigen were similar to those of the noncancerous bile ductules. In contrast, mutational signature cluster analyses revealed that CLC formed a cluster associated with mismatch-repair deficiency (dMMR), which was separate from iCCA. Therefore, to evaluate MMR status, we performed immunostaining of four MMR proteins (PMS2, MSH6, MLH1, and MSH2) and detected dMMR in almost all CLCs. In conclusion, CLC had highly similar characteristics to iCCA but not to HCC. CLC can be categorized as a subtype of iCCA. In contrast, CLC has characteristics of dMMR tumors that are not found in iCCA, suggesting that it should be treated distinctly from iCCA. © 2024 The Pathological Society of Great Britain and Ireland.

Makino K ，Ishii T ，Takeda H ，Saito Y ，Fujiwara Y ，Fujimoto M ，Ito T ，Wakama S ，Kumagai K ，Munekage F ，Horie H ，Tomofuji K ，Oshima Y ，Uebayashi EY ，Kawai T ，Ogiso S ，Fukumitsu K ，Takai A ，Seno H ，Hatano E ... -  《-》

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

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. 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). 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.

Nguyen Canh H ，Takahashi K ，Yamamura M ，Li Z ，Sato Y ，Yoshimura K ，Kozaka K ，Tanaka M ，Nakanuma Y ，Harada K ... -  《-》

Mixed hepatocellular cholangiocarcinoma tumors: Cholangiolocellular carcinoma is a distinct molecular entity.

Mixed hepatocellular cholangiocarcinoma (HCC-CCA) is a rare and poorly understood type of primary liver cancer. We aimed to perform a comprehensive molecular characterization of this malignancy. Gene expression profiling, DNA copy number detection, and exome sequencing using formalin-fixed samples from 18 patients with mixed HCC-CCA were performed, encompassing the whole histological spectrum of the disease. Comparative genomic analysis was carried out, using independent datasets of HCC (n=164) and intrahepatic cholangiocarcinoma (iCCA) (n=149). Integrative genomic analysis of HCC-CCAs revealed that cholangiolocellular carcinoma (CLC) represents a distinct biliary-derived entity compared with the stem-cell and classical types. CLC tumors were neural cell adhesion molecule (NCAM) positive (6/6 vs. 1/12, p<0.001), chromosomally stable (mean chromosomal aberrations 5.7 vs. 14.1, p=0.008), showed significant upregulation of transforming growth factor (TGF)-β signaling and enrichment of inflammation-related and immune response signatures (p<0.001). Stem-cell tumors were characterized by spalt-like transcription factor 4 (SALL4) positivity (6/8 vs. 0/10, p<0.001), enrichment of progenitor-like signatures, activation of specific oncogenic pathways (i.e., MYC and insulin-like growth factor [IGF]), and signatures related to poor clinical outcome. In the classical type, there was a significant correlation in the copy number variation of the iCCA and HCC components, suggesting a clonal origin. Exome sequencing revealed an average of 63 non-synonymous mutations per tumor (2 mean driver mutations per tumor). Among those, TP53 was the most frequently mutated gene (6/21, 29%) in HCC-CCAs. Mixed HCC-CCA represents a heterogeneous group of tumors, with the stem-cell type characterized by features of poor prognosis, and the classical type with common lineage for HCC and iCCA components. CLC stands alone as a distinct biliary-derived entity associated with chromosomal stability and active TGF-β signaling. Molecular analysis of mixed hepatocellular cholangiocarcinoma (HCC-CCA) showed that cholangiolocellular carcinoma (CLC) is distinct and biliary in origin. It has none of the traits of hepatocellular carcinoma (HCC). However, within mixed HCC-CCA, stem-cell type tumors shared an aggressive nature and poor outcome, whereas the classic type showed a common cell lineage for both the HCC and the intrahepatic CCA component. The pathological classification of mixed HCC-CCA should be redefined because of the new molecular data provided.

Moeini A ，Sia D ，Zhang Z ，Camprecios G ，Stueck A ，Dong H ，Montal R ，Torrens L ，Martinez-Quetglas I ，Fiel MI ，Hao K ，Villanueva A ，Thung SN ，Schwartz ME ，Llovet JM ... -  《-》

[Combined hepatocellular-cholangiocarcinoma (cholangiolocellular type) with stem-cell features: a clinicopathologic analysis of 26 cases].

Xu J ，Zhang C ，Qiao A ，Xi Y ... -  《-》

The Dominant Component and Clinicopathological Characteristics of Combined Hepatocellular-cholangiocarcinoma After Radical Resection.

Combined hepatocellular cholangiocarcinoma (cHCC-CCA) is a rare subtype of primary liver carcinoma, characterized by the unequivocal presence of both hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA). However, its clinicopathological characteristics have not yet been thoroughly elucidated. In particular, cholangiolocellular carcinoma (CLC) was classified as a subtype of cHCC-CCA according to the 2010 World Health Organization (WHO) classification. However, according to the 2019 WHO classification, tumors displaying histological features consistent with CLC but lacking evidence of hepatocellular differentiation should be regarded as a distinct subtype of iCCA. Nevertheless, there may be notable differences in prognosis between CLC and iCCA, indicating the necessity for refining the classification when devising clinical treatment strategies. This study aimed to determine the clinicopathological features and prognostic factors of cHCC-CCAs following radical resection. Between January 2010 and September 2020, based on the 2010 WHO classification, we retrospectively studied the clinicopathological features and prognoses of patients with cHCC-CCAs in relation to the pathological dominant classification. The patients were classified according to the pathological dominant components of cHCC-CCA as HCC-dominant (HCC-D), iCCA-dominant (iCCA-D), or CLC-dominant (CLC-D). Data of 55 patients who underwent primary radical hepatectomy for cHCC-CCA were analyzed. The prevalences of each dominant classification were HCC-D, 21 (38.2%); iCCA-D, 11 (20.0%); and CLC-D, 23 (41.8%). Multivariate analysis showed that dominant classification was an independent risk factor for recurrence and cancer-specific survival (CSS). The dominant classification of cHCC-CCA has the potential to predict recurrence and CSS.

Matsubara K ，Kobayashi T ，Tadokoro T ，Namba Y ，Fukuhara S ，Oshita KO ，Honmyo N ，Kuroda S ，Arihiro K ，Ohdan H ... -  《-》