ß2-microglobulin expression is associated with aggressive histology, activated tumor immune milieu, and outcome in colon carcinoma.

OBJECTIVES: We sought to assess the expression of human leukocyte antigen (HLA) proteins and ß2-microglobulin (B2M) in tumor cells and the relationship with immune microenvironment and outcome in colorectal cancer (CRC). METHODS: A total of 953 CRC cases were evaluated by immunohistochemistry for HLA class I, HLA class II, and B2M. The expression level of these biomarkers was correlated with clinicopathologic information, BRAF V600E and mismatch repair (MMR) proteins, and the quantitated expression levels of immune cells (CD8 and CD163) and immune regulatory proteins (FoxP3, programmed cell death 1 ligand 1 [PD-L1], and LAG3). RESULTS: We found that B2M-low tumors were statistically correlated with aggressive histologic features, including higher stage, higher grade, extramural venous invasion, perineural invasion, and distant metastasis. Expression of B2M was positively correlated (R2 = 0.3) and significantly associated with MMR-deficient tumors (P < .001); B2M-low tumors were also associated with an "immune cold"' microenvironment, including a reduced number of immune cells (CD8 and CD163), reduced expression of immune regulatory proteins by immune cells (PD-L1, FoxP3, and LAG3), and reduced tumor cell expression of PD-L1. These B2M-low tumors correlated with lower disease-specific survival (P = .018), a finding that maintained significance only for the proficient MMR cohort (P = .037). CONCLUSIONS: Our findings suggest that B2M expression may support predictive models for both outcome and checkpoint inhibitor therapy treatment response for colorectal adenocarcinoma.

3D observations provide striking findings in rubber elasticity.

The mechanical response of rubbers has been ubiquitously assumed to be only a function of the imposed strain. Using innovative X-ray measurements capturing the three-dimensional spatial volumetric strain fields, we demonstrate that rubbers and indeed many common engineering polymers undergo significant local volume changes. But remarkably, the overall specimen volume remains constant regardless of the imposed loading. This strange behavior which also leads to apparent negative local bulk moduli is due to the presence of a mobile phase within these materials. Combining X-ray tomographic observations with high-speed radiography to track the motion of the mobile phase, we have revised classical thermodynamic frameworks of rubber elasticity. The work opens broad avenues to understand not only the mechanical behavior of rubbers but a large class of widely used engineering polymers.

Assessing venous invasion in stage II colon cancer: optimal elastin stains and survival analysis.

AIMS: Venous invasion (VI) in colorectal carcinoma influences treatment strategies, especially in early stages. Despite elastin staining effectiveness in detecting VI, guidelines for its routine application, including the optimal number of slides for staining, are limited. METHODS: Elastin staining was performed for VI assessment in patients with colorectal adenocarcinoma. Patients were categorised into two groups: single elastin stain group (SEG, n=248) and multiple elastin stain group (MEG, n=204). RESULTS: The average number of elastin-stained blocks was 2±1.7, increasing to 3.3±1.9 in MEG. VI detection was significantly higher in patients in MEG (50.5%) compared with SEG (37.0%) (p=0.004). VI detection rate was higher in MEG (63.7%) than in SEG (46.0%) among patients with stage III-IV disease (p=0.011), but did not significantly differ among patients with stage I-II disease. Staining two blocks improved VI detection without additional gains from more stains. Compared with elastin performed on a single block, VI detected by elastin stain on two or more blocks did not significantly impact progression-free or disease-free survival with stage II patients. CONCLUSIONS: Employing two elastin stains on separate blocks significantly enhances VI detection in colorectal carcinoma without additional benefits from more extensive staining. This study suggests that while increasing sensitivity for VI detection, staining beyond two blocks may not benefit prognostication and could be counterproductive, warranting further research. We emphasise the need for strategic use of the elastin stain and cautious interpretation of the increased detection sensitivity of multiple elastin stains.

von Meyenburg complexes are more frequently associated with cholangiocarcinoma.

AIM: There is some evidence that von Meyenburg complexes (VMCs) can progress to cholangiocarcinoma (CC). This study aimed to evaluate the prevalence of VMCs in CC cases. METHODS: All hepatic resections and explants with intra-hepatic CC (I-CC) and hilar-CC (H-CC) from 1985 to 2020 were studied. Hepatic resections (n=68) for benign lesions or metastatic colonic carcinoma and 15 cases with cirrhosis without any cancer were used as controls. RESULTS: A total of 118 cases of CC (88 I-CC, 30 H-CC) were identified. Of these, 61 (52%) patients had no known background liver disease, and 20 (17%) had cirrhosis. Associated liver disorders included metabolic dysfunction-associated steatohepatitis (23), chronic viral hepatitis B or C (13), biliary disease (primary or secondary sclerosing cholangitis) (8), polycystic kidney disease (6), cryptogenic cirrhosis (5) and others miscellaneous disorders (7). VMCs were present in 34 (39%) of 88 I-CC cases and 7 (23%) of 30 H-CC cases. VMCs were present within the tumour (20 cases), outside the cancer (21 cases) or at both locations (10 cases). VMCs with dysplasia/carcinoma in situ were seen in 19 of 41 (46%) cases with CC and VMCs. In addition, bile duct adenomas were identified in 6 (5%) of CC. 7% of controls showed the presence of VMCs compared with 35% of CC cases (p<0.05). CONCLUSIONS: VMCs are seen far more frequently in patients with CC than in the control group. The findings support the hypothesis that VMCs could represent a precursor of CC or a marker for a higher risk of developing CC.

Transcriptionally Active Human Papillomavirus Infection in a Minority of Esophageal Squamous Cell Carcinomas in North America.

The role of Human papillomavirus (HPV) infection in esophageal squamous cell carcinoma (ESCC) is a topic of ongoing debate. This study used two screening approaches to look for evidence of HPV infection in esophageal squamous cell carcinoma. We initially checked for HPV infection in a randomly selected group of 53 ESCC cases. We did not detect any tumors positive for high-risk HPV. However, during clinical practice, we identified an HPV-positive ESCC in the distal esophagus, which tested positive for HPV16. This index case was TP53 wild-type, as determined by next-generation DNA sequencing (NGS). Since TP53 mutations are rare in other HPV-driven cancers, we improved our screening method by limiting our screen to a subset of ESCC cases without TP53 mutations. A second screen of 95 ESCCs (from 93 patients) sequenced by NGS revealed an additional 7 ESCCs with TP53 wild-type status (7.3% of the total). Of the 7 cases, 2 cases were found to be high-risk HPV positive. Both patients also tested positive for circulating cell-free HPV DNA and had a complete response to neoadjuvant chemoradiation. The index patient had microscopic residual tumor following neoadjuvant therapy. The patient underwent adjuvant immunotherapy and remained disease free after 22 months of surveillance. This study affirms the transcriptionally active status of high-risk HPV in a minority of ESCC patients in North America.

Large and Extensive Multilocular Peritoneal Inclusion Cysts Lack Genomic Alterations and Follow an Indolent Clinical Course Despite Rare Recurrences.

Peritoneal inclusion cysts (PICs) are unilocular or multilocular cystic lesions lined by bland mesothelial cells. While most are small and localized, rare examples may be large or multifocal with diffuse peritoneal involvement, causing clinical and even pathologic concern for malignancy. We examined 20 PIC, including 8 large solitary and 12 multifocal lesions. Solitary PIC were found in 7 female and 1 male patients ranging from 19 to 55 (median: 37) years. Expanded collagenous (n=2) or edematous (n=1) areas were occasionally seen in the septae, and 1 had microscopic foci of myxoid stroma. Four had hobnail cells, and 1 had minor areas of papillary mesothelial hyperplasia. Multifocal PICs occurred in 9 female and 3 male patients ranging from 26 to 80 (median: 53) years. Three showed extensive associated fibrosis with entrapment of preexisting adipose tissue, 2 had areas resembling granulation tissue, and 3 had scattered foci of myxoid stroma. Hobnail cells were present in 9, papillary mesothelial hyperplasia in 2, entrapped single cells in 1, and 2 had areas resembling adenomatoid tumors. Two of the multifocal PICs had limited local recurrences at 18 and 21 months. No patients died of disease. Clonal alterations were not identified in any of the tested PICs (mutational and fusion analysis in 5, chromosomal microarray in 1). Despite limited local recurrences, we demonstrate that even large and multifocal PICs may lack identifiable genomic alterations and are associated with benign outcomes.

Esophageal squamous cell carcinoma with pagetoid spread: a clinicopathologic study.

Pagetoid spread in esophageal squamous epithelium associated with underlying esophageal adenocarcinoma (EAC) has been well studied. Case reports describing pagetoid spread of esophageal squamous cell carcinomas (ESCC) also exist in the literature. The latter, however, has not been systematically studied. In this study, we report seven cases of pagetoid spread associated with ESCC. The clinical, morphologic, and immunophenotypic profiles of pagetoid spread in the context of ESCC and EAC are compared. Cases of pagetoid spread of ESCC were identified through computerized search of pathology archives at five institutions. Additional cases were identified through manual review of surgical resection cases of treatment naive ESCC in Mass General Brigham (MGB) pathology archive. Clinical history was collected via chart review. Immunohistochemistry for CK7, CK20, CDX2, p53, p63, and p40 was performed on selected cases. A computerized search of pathology archives of five institutions revealed only two cases. A manual review of 76 resected untreated ESCC revealed five additional cases with unequivocal pagetoid spread of ESCC, indicating the condition was not uncommon but rarely reported. Patient age ranged from 54 to 78 years (median, 65). There were six women and one man. One case had in situ disease, five had pT1 (1 pT1a and 4 pT1b), and one had pT3 disease. One of the patients with pT1 tumor had a positive lymph node, while the remaining six patients were all N0. Four tumors were in the proximal to mid esophagus, and three in the distal esophagus. Patient survival ranged from 25 months to more than 288 months. The pagetoid tumor cells demonstrated enlarged, hyperchromatic nuclei with variable amounts of eosinophilic cytoplasm. The cytoplasm was often condensed to the perinuclear area, creating peripheral clearing. By immunohistochemistry, the pagetoid cells were positive for p40 (6/6) and p63 (7/7) and negative for CDX2 (7/7). The tumor cells showed mutant-type staining for p53 in five of seven cases. One of the patients had pagetoid tumor cells at the resection margin and subsequently had recurrent disease 2 years later. All other patients had negative resection margins and did not have local recurrence. Four cases of pagetoid spread in the context of EAC were used as a comparison group. Previously published studies were also analyzed. These tumors were all located in the distal esophagus or gastroesophageal junction. All cases were associated with underlying invasive EAC. Pagetoid spread associated with EAC often had cytoplasmic vacuoles or mucin. They were more frequently positive for CK7 than pagetoid ESCC (p = 0.01). Both ESCC and EAC may give rise to pagetoid spread of tumor cells within surface squamous epithelium. Pagetoid spread from ESCC and EAC have overlapping morphologic features. P40 and p63 immunostains can facilitate the distinction between ESCC and EAC. P53 immunostain can aid in confirmation of malignancy. Understanding their overlapping pathologic features will help pathologists avoid pitfalls and diagnose these lesions correctly on biopsy specimens.

Prognostic factors in clinicopathology of oesophagogastric adenocarcinoma: a single-centre longitudinal study of 347 cases over a 20-year period.

Oesophagogastric adenocarcinoma (EGA) includes oesophageal (EA), gastro-oesophageal junctional (GEJA), and gastric (GA) adenocarcinomas. The prognostic values of clinicopathological factors in these tumours remain obscure, especially for GEJA that has been inconsistently classified and staged. We studied the prognosis of EGA patients among the three geographic groups in 347 consecutive patients with a median age of 70 years (range 47-94). All patients were male, and 97.1% were white. Based on tumour epicentre location, EGAs were sub-grouped into EA (over 2 cm above the GEJ; n=3, 18.1%), GEJA (within 2 cm above and 3 cm below the GEJ; n=231, 66.6%), and GA (over 3 cm below the GEJ; n=53, 15.3%). We found that the median overall survival (OS) was the longest in EA (62.9 months), compared to GEJA (33.4), and GA (38.1) (p<0.001). Significant risk factors for OS included tumour location (p=0.018), size (p<0.001), differentiation (p<0.001), adenocarcinoma subtype (p<0.001), and TNM stage (p<0.001). Independent risk factors for OS comprised low-grade papillary adenocarcinoma [odds ratio (OR) 0.449, 95% confidence interval (CI) 0.214-0.944, p<0.05), mixed adenocarcinoma (OR 1.531, 95% CI 1.056-2.218, p<0.05), adenosquamous carcinoma (OR 2.206, 95% CI 1.087-4.475, p<0.05), N stage (OR 1.505, 95% CI 1.043-2.171, p<0.05), and M stage (OR 10.036, 95% CI 2.519-39.993, p=0.001)]. EGA was further divided into low-risk (common well-moderately differentiated tubular and low-grade papillary adenocarcinomas) and high-risk (uncommon adenocarcinoma subtypes, adenosquamous carcinoma) subgroups. In this grouping, the median OS was significantly longer in the low-risk (83 months) than in the high-risk (10 months) subgroups (p<0.001). In conclusion, the prognosis of EGA patients was significantly better in EA than in GEJA or GA and could be stratified into low and high-risk subgroups with significantly different outcomes.

Esophageal adenocarcinoma heterogeneity in clinicopathology and prognosis: A single center longitudinal study of 146 cases over a 20-year period.

Recent genomic studies suggest that esophageal adenocarcinoma (EAC) is not homogeneous and can be divided into true (tEAC) and probable (pEAC) groups. We compared clinicopathologic and prognostic features between the two groups of EAC. Based on endoscopic, radiologic, surgical, and pathologic reports, tumors with epicenters beyond 2 cm of the gastroesophageal junction (GEJ) were assigned to the tEAC group (N = 63), while epicenters within 2 cm of, but not crossing the GEJ, were allocated to the pEAC group (N = 83). All 146 consecutive patients were male (age: median 70 years, range: 51-88) and White-predominant (98.6 %). There was no significant difference in gastroesophageal reflux disease, obesity, comorbidity, and the prevalence of Barrett's esophagus, and cases diagnosed during endoscopic surveillance. However, compared to the pEAC group, the tEAC group had significantly more cases with hiatal hernia (P = 0.003); their tumors were significantly smaller in size (P = 0.007), more frequently with tubular/papillary adenocarcinoma (P = 0.001), had fewer cases with poorly cohesive carcinoma (P = 0.018), and demonstrated better prognosis in stage I disease (P = 0.012); 5-year overall survival (34.9 months) was significantly longer (versus 16.8 months in pEACs) (P = 0.043). Compared to the patients without resection, the patients treated with endoscopic or surgical resection showed significantly better outcomes, irrespective of stages. We concluded that EACs were heterogeneous with two distinct tEAC and pEAC groups in clinicopathology and prognosis; resection remained the better option for improved outcomes. CONDENSED ABSTRACT: Esophageal adenocarcinoma can be divided into true or probable groups with distinct clinicopathology and better prognosis in the former than in the latter. we showed that resection remained the better option for improved outcomes.

SOX17 enables immune evasion of early colorectal adenomas and cancers.

A hallmark of cancer is the avoidance of immune destruction. This process has been primarily investigated in locally advanced or metastatic cancer1-3; however, much less is known about how pre-malignant or early invasive tumours evade immune detection. Here, to understand this process in early colorectal cancers (CRCs), we investigated how naive colon cancer organoids that were engineered in vitro to harbour Apc-null, KrasG12D and Trp53-null (AKP) mutations adapted to the in vivo native colonic environment. Comprehensive transcriptomic and chromatin analyses revealed that the endoderm-specifying transcription factor SOX17 became strongly upregulated in vivo. Notably, whereas SOX17 loss did not affect AKP organoid propagation in vitro, its loss markedly reduced the ability of AKP tumours to persist in vivo. The small fraction of SOX17-null tumours that grew displayed notable interferon-γ (IFNγ)-producing effector-like CD8+ T cell infiltrates in contrast to the immune-suppressive microenvironment in wild-type counterparts. Mechanistically, in both endogenous Apc-null pre-malignant adenomas and transplanted organoid-derived AKP CRCs, SOX17 suppresses the ability of tumour cells to sense and respond to IFNγ, preventing anti-tumour T cell responses. Finally, SOX17 engages a fetal intestinal programme that drives differentiation away from LGR5+ tumour cells to produce immune-evasive LGR5- tumour cells with lower expression of major histocompatibility complex class I (MHC-I). We propose that SOX17 is a transcription factor that is engaged during the early steps of colon cancer to orchestrate an immune-evasive programme that permits CRC initiation and progression.

Interplay between B7-H3 and HLA class I in the clinical course of pancreatic ductal adenocarcinoma.

Human leukocyte antigen (HLA) class I defects are associated with cancer progression. However, their prognostic significance is controversial and may be modulated by immune checkpoints. Here, we investigated whether the checkpoint B7-H3 modulates the relationship between HLA class I and pancreatic ductal adenocarcinoma (PDAC) prognosis. PDAC tumors were analyzed for the expression of B7-H3, HLA class I, HLA class II molecules, and for the presence of tumor-infiltrating immune cells. We observed defective HLA class I and HLA class II expressions in 75% and 59% of PDAC samples, respectively. HLA class I and B7-H3 expression were positively related at mRNA and protein level, potentially because of shared regulation by RELA, a sub-unit of NF-kB. High B7-H3 expression and low CD8+ T cell density were indicators of poor survival, while HLA class I was not. Defective HLA class I expression was associated with unfavorable survival only in patients with low B7-H3 expression. Favorable survival was observed only when HLA class I expression was high and B7-H3 expression low. Our results provide the rationale for targeting B7-H3 in patients with PDAC tumors displaying high HLA class I levels.

Advancements in diagnosing IgG4-related disease of the head and neck: Navigating diagnostic pitfalls.

IgG4-related disease (IgG4-RD) is an immune-mediated condition affecting nearly any organ. This review focuses on the nuances of diagnosing IgG4-RD affecting the head and neck. Salivary gland involvement, especially of the submandibular glands, often permits a definitive diagnosis on biopsy. However, elevated IgG4+ plasma cells are nonspecific and can be seen in chronic sialadenitis, lymphoma, and other mimics. Careful correlation of clinical and pathological findings is essential. Given the significant overlap with chronic sinusitis, IgG4-RD of the sinonasal region is difficult to diagnose histologically. Laryngeal and pharyngeal involvement appears rare as an isolated finding of IgG4-RD. Mastoid disease is uncommon and remains a diagnosis of exclusion. Thyroid manifestations pose challenges given unclear diagnostic criteria - Riedel's thyroiditis likely represents IgG4-RD, but the fibrosing variant of Hashimoto's thyroiditis as a form of the so-called 'IgG4-related thyroiditis' requires better characterisation. Eosinophilic angiocentric fibrosis, despite histologic similarities, only partially overlaps with IgG4-RD. This review aims to guide diagnosing IgG4-RD in the head and neck through a systematic, organ-focused discussion of the clinical context, the utility of immunostaining, histological mimics, and controversial issues that pose diagnostic pitfalls. Increased awareness of the nuances and difficulties diagnosing IgG4-RD affecting the head and neck will improve recognition of this protean disease.

Lymphoglandular Complex-Like Colorectal Carcinoma-A Series of 20 Colorectal Cases, Including Newly Reported Features of Malignant Behavior.

Distinguishing colon carcinoma that is surrounded by well-circumscribed lymphoid tissue from adenomas involving lymphoglandular complexes can be difficult. We assessed a multi-institutional international cohort of 20 colorectal carcinomas with associated prominent lymphoid infiltrates, which we referred to as lymphoglandular complex-like carcinoma (LGCC). We collected clinical and endoscopic features, including lesion size, endoscopic appearance, location, procedure, follow-up, AJCC stage, and mismatch repair status. We recorded the presence of the following histologic features: haphazard gland distribution, gland angulation, gland fusion, solid nest formation, single-cell formation, stromal desmoplasia, presence of lymphovascular invasion and perineural invasion, presence of lamina propria, cytologic atypia as low- or high-grade, presence of goblet cells in the invasive component, and the presence of a surface lesion. Most cases (9 of 13) were described endoscopically as sessile polyps with an average size of 1.56 cm. Most cases (90%) were associated with a surface lesion, of which the majority were tubular adenomas, though a subset was associated with sessile serrated lesions with dysplasia (3 of 18). All cases of LGCC demonstrated haphazard gland distribution and either gland angulation, fusion, or solid nest formation. A portion of cases demonstrated single-cell infiltration (35%) and desmoplasia (50%), and rarely lymphovascular invasion was present (5%). A subset (10%) of cases invaded beyond the submucosa. Deficient mismatch repair was present in 22% (2 of 9) of cases for which it was performed. In cases of colectomy or completion colectomy, nodal metastasis was present in 38% (3 of 8). No cases demonstrated disease recurrence or disease-specific mortality. Overall, LGCC represents an enigmatic subset of carcinomas that is important to distinguish from adenomas involving lymphoglandular complexes due to its varying prognostic outcomes.

Chronic metabolic stress drives developmental programs and loss of tissue functions in non-transformed liver that mirror tumor states and stratify survival.

Under chronic stress, cells must balance competing demands between cellular survival and tissue function. In metabolic dysfunction-associated steatotic liver disease (MASLD, formerly NAFLD/NASH), hepatocytes cooperate with structural and immune cells to perform crucial metabolic, synthetic, and detoxification functions despite nutrient imbalances. While prior work has emphasized stress-induced drivers of cell death, the dynamic adaptations of surviving cells and their functional repercussions remain unclear. Namely, we do not know which pathways and programs define cellular responses, what regulatory factors mediate (mal)adaptations, and how this aberrant activity connects to tissue-scale dysfunction and long-term disease outcomes. Here, by applying longitudinal single-cell multi -omics to a mouse model of chronic metabolic stress and extending to human cohorts, we show that stress drives survival-linked tradeoffs and metabolic rewiring, manifesting as shifts towards development-associated states in non-transformed hepatocytes with accompanying decreases in their professional functionality. Diet-induced adaptations occur significantly prior to tumorigenesis but parallel tumorigenesis-induced phenotypes and predict worsened human cancer survival. Through the development of a multi -omic computational gene regulatory inference framework and human in vitro and mouse in vivo genetic perturbations, we validate transcriptional (RELB, SOX4) and metabolic (HMGCS2) mediators that co-regulate and couple the balance between developmental state and hepatocyte functional identity programming. Our work defines cellular features of liver adaptation to chronic stress as well as their links to long-term disease outcomes and cancer hallmarks, unifying diverse axes of cellular dysfunction around core causal mechanisms.

Dysregulated Repeat Element Viral-like Immune Response in Hepatocellular Carcinoma.

Purpose: Dysregulation of viral-like repeat RNAs are a common feature across many malignancies that are linked with immunological response, but the characterization of these in hepatocellular carcinoma (HCC) is understudied. In this study, we performed RNA in situ hybridization (RNA-ISH) of different repeat RNAs, immunohistochemistry (IHC) for immune cell subpopulations, and spatial transcriptomics to understand the relationship of HCC repeat expression, immune response, and clinical outcomes. Experimental Design: RNA-ISH for LINE1, HERV-K, HERV-H, and HSATII repeats and IHC for T-cell, Treg, B-cell, macrophage, and immune checkpoint markers were performed on 43 resected HCC specimens. Spatial transcriptomics on tumor and vessel regions of interest was performed on 28 specimens from the same cohort. Results: High HERV-K and high LINE1 expression were both associated with worse overall survival. There was a positive correlation between LINE1 expression and FOXP3 T-regulatory cells (r = 0.51 p < 0.001) as well as expression of the TIM3 immune checkpoint (r = 0.34, p = 0.03). Spatial transcriptomic profiling of HERV-K high and LINE-1 high tumors identified elevated expression of multiple genes previously associated with epithelial mesenchymal transition, cellular proliferation, and worse overall prognosis in HCC including SSX1, MAGEC2, and SPINK1. Conclusion: Repeat RNAs may serve as useful prognostic biomarkers in HCC and may also serve as novel therapeutic targets. Additional study is needed to understand the mechanisms by which repeat RNAs impact HCC tumorigenesis.

Focal nodular hyperplasia-like nodules arising in the setting of hepatic vascular disorders with portosystemic shunting show ß-catenin activation.

Hepatocellular nodules can develop in the setting of chronic hepatic vascular disorders including those characterized by portosystemic shunts such as Abernethy malformation and post-Fontan procedure. The nodules can range from benign lesions such as regenerative nodules, focal nodular hyperplasia (FNH), and hepatocellular adenoma (HCA) to malignant neoplasms such as hepatocellular carcinoma (HCC). In many instances, these nodules are difficult to place into well-defined categories based on radiologic or histologic features. Nodular lesions that resemble FNH are common in this context and have been described as FNH-like nodules, the nature of which is not well-established. This study examines 6 liver resections from patients with vascular disease characterized by portosystemic shunts. A wide range of nodules were present in these cases, including regenerative nodules (n = 2), FNH and FNH-like (n = 30), HCA (n = 10), HCA-like (n = 13), and HCC (n = 2). Six nodules from 3 patients were categorized as FNH-like due to one or more features such as nodular architecture, fibrous septa, and ductular reaction, but lack of typical map-like glutamine synthetase (GS) staining. Further characterization of these 6 FNH-like nodules showed diffuse GS staining in all nodules (3 diffuse homogeneous, 3 diffuse heterogeneous). Targeted next-generation sequencing identified CTNNB1 alterations in all tested FNH-like nodules (n = 4). These results indicate that FNH-like nodules in the setting of chronic hepatic vascular disorders can be neoplastic. Since the presence of ß-catenin activation portends a potential risk for malignant progression, GS and ß-catenin immunohistochemistry should be obtained in all cases showing FNH-like morphology, with molecular analysis performed in cases with indeterminate staining pattern.