HPHS Journal Watch March and April 2025 – Hans Popper Hepatopathology Society

The American Journal of Surgical Pathology

Clinicopathologic Features of a Rare and Underrecognized Variant of Early-stage Primary Biliary Cholangitis With Ductopenia

Yu H, Lv T, Li S, et. al. Am J Surg Pathol. 2025 Mar 1;49(3):265-272.

https://pubmed.ncbi.nlm.nih.gov/39704223

The development of ductopenia does not consistently parallel the progression of fibrosis in primary biliary cholangitis (PBC). Ductopenia in patients with early stage PBC without significant fibrosis has been referred to as the premature ductopenic variant of PBC, or as early-stage PBC without ductopenia. In this work, the authors explore the clinicopathologic features of patients with early-stage PBC with ductopenia. The study cohort includes a total of 141 patients with early-stage PBC, 36 of which exhibit ductopenia. Patients with early-stage PBC with ductopenia were significantly younger than those without ductopenia, had higher LFTs, bilirubin, and serum cholesterol, and had a significantly lower response rate to UDCA-based therapy according to Paris II, Barcelona, and Rotterdam criteria. Biochemical response rates increased with the addition of second line drugs. There were, however, no significant differences in short-term outcomes between the groups. With regard to histologic features, the degree of cholangitis and hepatitic activity were lower in patients with ductopenia, but features of chronic cholestasis (i.e. copper deposition, cholatestasis, increase in CK7-positive hepatocytes) are higher. The authors conclude from this study that patients with early-stage PBC with ductopenia exhibit higher liver function tests and a suboptimal response to first-line therapies. They propose that serum cholesterol levels can be used to help identify patients that may benefit from the addition of second-line therapies.

Intraductal Polypoid Neoplasm in the Intrahepatic Large Bile Ducts of Small Duct-type Intrahepatic Cholangiocarcinoma May Result from Cancerization of Ducts

Nakanuma Y, Kakuda Y, Matsubayashi H, Sugino T. Am J Surg Pathol. 2025 Mar 1;49(3):284-293.

https://pubmed.ncbi.nlm.nih.gov/39757374

Grossly visible intaluminal polypoid growths are occasionally seen in the large caliber bile ducts adjacent to mass-forming small duct-type intrahepatic cholangiocarcinoma (iCCA). The authors investigate a cohort of 121 small duct-type iCCA. Intraductal polypoid neoplasms were identified in 8 (6.6%) cases and showed cast-like growth involving the large bile ducts adjacent to or at the periphery of the main tumor mass. There are similar histologic features and architectural patterns of growth between the mass-forming tumors and the intraductal polypoid growth. In addition, the intraductal polypoid neoplasm and mass-forming components of the tumor showed near identical immunophenotypes with respect to the structural and secretory proteins (CK7, CK20, MUC2, MUC6, NCAM, S100P, and CRP) as well p16, p53, IDH1, SMAD4, FGFR, MTAP, BAP, ARID, and MDM2, proteins known to be involved with iCCA carcinogenesis. All cases showed a biliary phenotype and showed an abrupt transition between the polypoid neoplasm and the background non-neoplastic epithelium. The authors conclude from this work that intraductal polypoid neoplasms reflect cancerization of ducts of small duct-iCCA. These intraductal polypoid neoplasms are distinct from intraductal papillary neoplasms of the bile duct (IPNM) and intraductal tubule-papillary neoplasms (ITPN) which are frequently non-invasive and may exhibit mucin overproduction and a non-biliary phenotype.

Cholangioblastic Cholangiocarcinoma (NIPBL::NACC1 Cholangiocarcinoma) Expanded Morphologic Spectrum and Further Genetic Characterization

Argani P, Oshima K, Anders RA et. al. Am J Surg Pathol. 2025 Apr 1;49(4):303-314.

https://pubmed.ncbi.nlm.nih.gov/39815455

Cholangioblastic cholangiocarcinoma is a histologically distinct neoplasm that primarily affects young women without underlying liver disease and is comprised of large and small cells forming solid trabecular and tubulocystic structures. There is immunophenotypic evidence of biliary differentiation and, characteristically, strong, diffuse immunoreactivity for inhibin. In 2021, the NIPBL::NACC1 gene fusion was discovered in this tumor, and has subsequently been confirmed in other published reports. In this work, the authors report 2 additional cases of cholangioblastic cholangiocarcinoma with distinctive morphologic features. The first case had been previously diagnosed as a biliary adenofibroma with malignant transformation. Re-review of this case demonstrated immunoreactivity for inhibin and the characteristic NIPBL::NACC1 gene fusion, resulting in the tumor being recharacterized as a highly cystic cholangioblastic cholangiocarcinoma. The second case was initially misclassified as metastatic well-differentiated neuroendocrine tumor, though re-review demonstrated focal biphasic large and small cell morphology, as well as immunoreactivity for inhibin and albumin by ISH, again highlighting the diverse morphologic features of this tumor type. In an expanded cohort of 7 cases, the authors report loss of chromosome 13q (including 13q14.2, where RB1 resides) in most cases, though RB protein expression was intact by IHC, as well as loss of 6q15-q16.3 and upregulation of INHA. The authors conclude from this work that the morphologic spectrum of cholangioblastic cholangiocarcinoma should be expanded to include both extensive cystic morphology, as well as progression to a higher grade tumor that lacks the classic biphasic cytology. They also suggest that RB1 loss might play a role in neoplastic progression.

Histopathology

Evolution of morphological changes in donor livers undergoing normothermic machine perfusion

Paterson AL, Gaurav R, Swift L, et. al. Histopathology. 2025 Mar;86(4):516-524.

https://pubmed.ncbi.nlm.nih.gov/39564610

There is a shortage of livers for transplantation and more than a fifth of retrieved livers are not transplanted. Normothermic machine perfusion (NMP) aims to improve organ perfusion and allows functional assessment of marginal organs using biochemical parameters. This study describes pattern of histological changes in 170 biopsies taken pre-NMP, after 4 h of NMP, end-NMP and at implantation from 50 livers undergoing NMP as part of standard transplant practice. 38% had large droplet macrovesicular steatosis pre-NMP, 32% had small droplet macrovesicular steatosis pre-NMP suggestive of acute cellular stress, the severity of which was unchanged in 64% during the perfusion period. Biopsies with at least moderate hepatocellular necrosis at end-NMP were less likely to be transplanted. Variation in the extent of hepatocyte necrosis was seen between biopsies, with 43% of transplanted cases showing less hepatocyte necrosis at implantation compared to end-NMP and 21% more severe necrosis. Patchy portal inflammation was present in 96% of pre-NMP biopsies. Sinusoidal dilation pre-NMP was more frequent in donation after circulatory death donors which typically persisted during NMP although improved by implantation. The histological changes in liver biopsies taken NMP pathway predominantly comprise donor-derived macrovesicular steatosis, stress-associated small droplet steatosis, retrieval/procedure-associated sinusoidal dilation and ischemic injury. Regional variations in necrosis extent are likely to limit the utility of biopsies taken during NMP to assess organ quality.

Clinicopathologic features and outcomes of hepatic inflammatory pseudotumour (IPT) and hepatic IPT-like lesions.

Nguyen ED, Wen KW, Kakar S, Balitzer D. Histopathology. 2025 Mar;86(4):525-535

https://pubmed.ncbi.nlm.nih.gov/39478419

81 cases of hepatic inflammatory pseudotumor (80 biopsies and 1 resection) from a single institution were reviewed and clinicopathological features as well as outcome were compiled. Patients frequently had a past medical history of malignancy (34%), biliary disease (15%), or prior intraabdominal surgery (24%), and often presented with multifocal hepatic lesions (36%). Histology review most commonly showed histiocytic (n = 29, 36%) and lymphoplasmacytic inﬂammatory background (n = 27, 34%), followed by neutrophilic in 24% (n = 19) of cases and paucicellular/sclerotic in 6% (n = 5). Speciﬁc organism was identiﬁed in a small minority of cases (15%) with most identified organisms being Klebsiella and Staphylococcus species. Most patients with available clinical follow-up demonstrated radiologic resolution and/or had repeat negative biopsy; a minority of patients (8%;6 cases out of 80) were subsequently diagnosed with neoplastic hepatic lesions. No signiﬁcant association was seen between histologic features and the subsequent clinical or pathologic diagnosis of hepatic neoplastic lesions. While most lesions regress spontaneously or with antibiotics, hepatic IPT-like features can be seen adjacent to unsampled or undersampled malignancy. Therefore, patients should be monitored clinically and radiographically and repeat biopsy performed in persistent lesions.

Expression of claudin-18.2 in cholangiocarcinoma: a comprehensive immunohistochemical analysis from a German tertiary centre.

Kinzler MN, Gretser S, Schulze F, et. al. Histopathology. 2025 Mar;86(4):640-646.

https://pubmed.ncbi.nlm.nih.gov/39731204

Anti‐claudin‐18.2 (CLDN18.2) therapy is approved for the treatment of gastric or gastro‐esophageal junction adenocarcinoma. This study looked at expression of CLDN18.2 in cholangiocarcinoma (CCA) to determine whether there is a subgroup of patients who might benefit from anti‐CLDN18.2 therapy. TMA of 160 patients with surgically resected CCA were used. 59.3% were diagnosed with iCCA (n = 95), 21.3% with perihilar (pCCA; n = 34) and 19.4% with distal (dCCA; n = 31) cholangiocarcinoma. Staining of VENTANA® CLDN18 and HER2/neu was performed. Tumor positivity for CLDN18.2 (≥ 75% of tumor cells with moderate‐to‐strong CLDN18 membranous staining) was determined analogously to the SPOTLIGHT and GLOW trials. HER2‐status assessed by IHC was negative in all cases (score 0). 7.4% (n = 7) of iCCA patients showed CLDN18 expression while 92.6% (n = 88) were negative. 2.9% (n = 2) in the SD‐iCCA subcohort showed positive staining of CLDN18, while 18.5% (n = 5) of LD‐iCCA expressed membranous CLDN18. CLDN18 expression was seen in 26.5% (n = 9 of 34) of the perihilar cholangiocarcinoma (pCCA) subgroup, while 16.1% (n = 5 of 31) were positive in distal cholangiocarcinoma (dCCA). A subset of patients with CCA exhibited marked expression of CLDN18.2 and clinical study evaluating the efficacy of anti‐CLDN18.2 therapy in patients with CCA needs to be considered.

Gastroenterology

Portal Fibrosis and the Ductular Reaction: Pathophysiological Role in the Progression of Liver Disease and Translational Opportunities.

Gupta V, Sehrawat TS, Pinzani M, Strazzabosco M. Gastroenterology. 2025 Apr;168(4):675-690.

https://pubmed.ncbi.nlm.nih.gov/39251168

This review paper highlights the pathogenesis of various types of ductular reaction (DR) and their role in fibrosis development across different chronic liver diseases. In cholangiopathies, biliary fibrosis primarily results from persistent liver injury and a maladaptive reparative response, wherein mesenchymal cells from the portal tract expand the portal matrix circumferentially, initiating fibrotic remodeling. Notch signaling, reactivated during biliary repair, plays a key role in regulating tubulogenesis and the transdifferentiation of hepatocytes into biliary epithelial cells. The interplay between DR, inflammatory cells, and endothelial cells is discussed. The review also explores the contribution of DR to fibrosis progression in alcohol-associated liver disease and metabolic dysfunction-associated steatotic liver disease. Finally, the authors consider the therapeutic potential of targeting DR to modify portal fibrosis and influence the course of liver disease, including approaches such as inhibition of morphogenetic signaling pathways and modulation of nuclear receptors such as FXR and peroxisome proliferator-activated receptors.

Gastroenterology & Hepatology

Clonorchis sinensis Promotes Intrahepatic Cholangiocarcinoma Progression by Activating FASN-Mediated Fatty Acid Metabolism

Ren X, Wu Y, Song T, et al. Gastroenterology and Hepatology. 2025 April; 40(4):1004-1015.

https://pubmed.ncbi.nlm.nih.gov/39806791

Intrahepatic cholangiocarcinoma (ICC) patients positive for Clonorchis sinensis infection exhibit significantly shorter overall survival compared to C. sinensis-negative ICC patients. This study aims to investigate the impact and underlying mechanisms of C. sinensis infection on ICC progression. RNA sequencing was utilized to identify downstream activated pathways and genes, revealing a marked upregulation of the fatty acid biosynthesis pathway. Notably, expression of fatty acid synthase (FASN), a key enzyme involved in long-chain fatty acid synthesis, was significantly increased. C. sinensis infection appears to profoundly affect tumor cell metabolism. In addition to glucose metabolism, cancer cells can acquire oncogenic mutations or adaptations that enable the use of alternative nutrients—such as fatty acids—to support tumor growth, metastasis, and disease progression. The overexpression of FASN can promote the proliferation of tumor cells and improve their potential of invasion and metastasis. Furthermore, the study demonstrated the potential mechanism of C. sinesis infection in promoting ICC through in vitro co culture and animal models

Hepatology

Aramchol improves hepatic fibrosis in metabolic dysfunction-associated steatohepatitis: Results of multimodality assessment using both conventional and digital pathology

Ratziu V, Yilmaz Y, Lazas D, et al. Hepatology. 2025 Mar 1;81(3):932-946.

https://pubmed.ncbi.nlm.nih.gov/38916482

In this prospective study the authors compared single-fiber digital image analysis with traditional pathologic assessment to quantify the antifibrotic effect of Aramchol, a stearoyl-CoA desaturase 1 inhibitor, in development for metabolic dysfunction–associated steatohepatitis (MASH). From the ARMOR trial 51 patients with MASH were treated with Aramchol and had paired pre-post treatment liver biopsies scored by consensus among 3 hepatopathologists. Then, separately these biopsies were assessed by a digital image analysis platform (PharmaNest) that generates a continuous Phenotypic Fibrosis Composite Severity Score (Ph-FCS) by digital pathology and artificial intelligence (DP/AI) for evaluating fibrosis improvement. Fibrosis improvement was defined as: ≥1 NASH Clinical Research Network (NASH- CRN) stage reduction; “improved” by ranked pair assessment; reduction in Ph- FCS (“any” for ≥0.3 absolute reduction and “substantial” for ≥25% relative reduction). Fibrosis improved in 31% of patients (NASH-CRN), 51% (ranked pair assessment), 74.5% (any Ph-FCS reduction), and 41% (substantial Ph- FCS reduction). Most patients with stable fibrosis by NASH-CRN or ranked pair assessment had a Ph-FCS reduction and fibrosis improvement increased with treatment duration. In addition, the antifibrotic effect of Aramchol was corroborated by reductions in liver stiffness, Pro-C3, and enhanced liver fibrosis. Changes in Ph-FCS were positively correlated with changes in liver stiffness. In conclusion, the findings indicate that DP/AI can be a promising tool for MASLD/MASH diagnosis and assessment of response to therapy in clinical trial since quantify antifibrotic effects with greater sensitivity and a larger dynamic range than conventional pathology.

Deep learning and digital pathology powers prediction of HCC development in steatotic liver disease

Nakatsuka T, Tateishi R, Sato M, et al. Mar 1;81(3):976-989.

https://pubmed.ncbi.nlm.nih.gov/38768142

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the leading cause of chronic liver diseases and may progress to hepatocellular carcinoma (HCC). In this retrospective study the author presented a deep learning (DL) model to predict HCC development using hematoxylin and eosin-stained whole-slide images of biopsy-proven steatotic liver disease. The cohort of patients came from the nationwide registry study focusing on steatotic liver without heavy alcohol consumption including 639 patients without HCC for ≥ 7 years after biopsy (non-HCC class) and 46 patients who developed HCC <7 years after biopsy (HCC class). The author’s adopted a DL model based on deep convolutional neural networks. Liver histology was assessed according to Kleiner fibrosis stage and graded using the NAFLD activity scoring system and the NASH Clinical Research Network criteria. DL model showed an accuracy of 81.0% and an AUC of 0.80 for predicting HCC development and detected the cases of HCC development in patients with mild fibrosis. Pathological features associated with HCC development were also highlighted by maps generated by the DL model, including nuclear atypia, hepatocytes with a high nuclear-cytoplasmic ratio, immune cell infiltration, fibrosis, and a lack of large fat droplets.

Genomic and transcriptomic analyses of chemical hepatocarcinogenesis aggravated by oncoprotein loss

Wang X, Liu Y, Zhang S, et. al. Hepatology. 2025 Apr 1;81(4):1181-1196.

https://pubmed.ncbi.nlm.nih.gov/39397357

New insights to hepatocellular carcinoma (HCC) pathogenesis can be obtained through in-depth analysis of HCC animal models, the most popular of which is based on the administration of the chemical carcinogen diethylnitrosamine (DEN). The enhancement of DEN-induced HCC has been also shown to be caused by ablation of several known oncoproteins (Met, Ptpn11/Shp2, Ikkβ, and Ctnnb1/β-catenin). The authors generated mutant mouse lines with hepatocyte-specific deletion of the above-listed proto-oncogenes and challenged them and wild-type (WT) mice with DEN, and performed whole exome sequencing (WES) and RNA-sequencing (RNAseq). RNA-sequencing revealed multiple changes in signaling pathways, in particular, upregulated epithelial-mesenchymal transition, cell migration, and tumor metastasis, as well as downregulated small molecule metabolism that was affected by oncoprotein ablation. Key molecules and pathways that are associated with hepatic innate immunity and implicated in liver tumorigenesis were also identified.

Hepatology Communications

EBV enhances immunotherapy sensitivity in intrahepatic cholangiocarcinoma through cGAS-STING pathway activation

Huang L, Zhong Q, Huang S, et al. Hepatol Commun . 2025 Mar 13;9(4):e0674.

https://pubmed.ncbi.nlm.nih.gov/40079734

EBV-associated intrahepatic cholangiocarcinoma (EBVaICC) is characterized by a significant CD8+ T cell infiltrate and generally has demonstrated better survival outcomes compared to other subtypes of intrahepatic cholangiocarcinoma, with a good response to PD1 immunotherapy. The authors evaluated 42 EBVaICC patients receiving anti-PD1 therapy at a single institution and analyzed treatment outcomes compared to 66 EBV negative ICC receiving anti-PD1 therapy, showing that patients receiving anti-PD1 therapy had significantly longer median overall survival (33.4 months vs 12.4 months), as well as progression-free survival (15.7 months vs 6.5 months). The authors also evaluated EBV-positive ICC cell lines, in which transcriptomic analyses revealed that these cell lines enhance CD8+ trafficking and toxicity via the cGAS-STING pathway and increased CXCL10 secretion. Blood samples from the patients show higher plasma levels of CXCL10 and IFN-gamma, suggesting that EBV may increase immunotherapy sensitivity via CXCL10.

Modern Pathology

How Do I Diagnose Fibrolamellar Carcinoma?

Einarsson H, Graham RP. Modern Pathology. 2025 April; 38(4): 100711.

https://pubmed.ncbi.nlm.nih.gov/39814265

This review article discusses the challenges associated with the diagnosis of fibrolamellar carcinoma (FLC). FLC is a rare and distinct type of primary liver cancer that was once considered a variant of conventional hepatocellular carcinoma (cHCC), but is now recognized as a separate entity based on its unique clinical, pathological, and molecular features. FLC is best diagnosed as a carcinoma composed of oncocytic cells with abundant cytoplasm and open chromatin with prominent macronucleoli—with or without intratumoral fibrosis. It typically affects individuals without underlying chronic liver disease and shows clear hepatocellular differentiation, with diffuse expression of hepatocellular markers. A defining molecular feature of FLC is the presence of the DNAJB1::PRKACA fusion gene, which is present in nearly all cases and is 100% specific in the setting of a primary liver carcinoma with hepatocellular differentiation. Diagnosing FLC can be challenging, as histologic features alone may lead to misclassification—even by expert pathologists. Immunohistochemical (IHC) markers such as KRT7 and CD68 can support the diagnosis, but their utility is limited by variability in expression and overlap with rare subtypes of cHCC. Therefore, molecular confirmation of the DNAJB1::PRKACA fusion is critical for an accurate diagnosis.

Prepared by:

Dana Balitzer, MD (Editor); University of California San Francisco

Beena Ahsan, MD; Henry Ford Health System

Shefali Chopra, MD; Keck Medical Center of USC

Clifton Fulmer, MD, PhD; Cleveland Clinic

Nigar Anjuman Khurram, MD; University of Pittsburgh

Yuanxin Liang, MD, PhD; Yale School of Medicine

Juan Putra, MD; Boston Children’s Hospital

Camila Simoes MD; UAMS College of Medicine

Angela R. Shih, MD; Massachusetts General Hospital