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BackgroundLiver cancer is the second leading cause of cancer-related deaths worldwide. Hepatocellular carcinoma (HCC) risk factors include chronic hepatitis, cirrhosis, and alcohol abuse, whereby tumorigenesis is induced through inflammation and subsequent fibrotic response. However, a subset of HCC arises in non-cirrhotic livers. We characterized the genomic and transcriptomic landscape of non-cirrhotic HCC to identify features underlying the disease’s development and progression.MethodsWhole genome and transcriptome sequencing was performed on 30 surgically resectable tumors comprised of primarily of non-cirrhotic HCC and adjacent normal tissue. Using somatic variants, capture reagents were created and employed on an additional 87 cases of mixed cirrhotic/non-cirrhotic HCC. Cases were analyzed to identify viral integrations, single nucleotide variants (SNVs), insertions and deletions (INDELS), copy number variants, loss of heterozygosity, gene fusions, structural variants, and differential gene expression.ResultsWe detected 3,750 SNVs/INDELS and extensive CNVs and expression changes. Recurrent TERT promoter mutations occurred in >52% of non-cirrhotic discovery samples. Frequently mutated genes included TP53, CTNNB1, and APOB. Cytochrome P450 mediated metabolism was significantly downregulated. Structural variants were observed at MACROD2, WDPCP and NCKAP5 in >20% of samples. Furthermore, NR1H4 fusions involving gene partners EWSR1, GNPTAB, and FNIP1 were detected and validated in 2 non-cirrhotic samples.ConclusionGenomic analysis can elucidate mechanisms that may contribute to non-cirrhotic HCC tumorigenesis. The comparable mutational landscape between cirrhotic and non-cirrhotic HCC supports previous work suggesting a convergence at the genomic level during disease progression. It is therefore possible genomic-based treatments can be applied to both HCC subtypes with progressed disease.HighlightsNon-cirrhotic HCC genomically resembles cirrhotic HCCComprehensive genome- and transcriptome-wide profiling allows detection of novel structural variants, fusions, and undiagnosed viral infectionsNR1H4 fusions may represent a novel mechanism for tumorigenesis in HCCNon-cirrhotic HCC is characterized by genotoxic mutational signatures and dysregulated liver metabolismClinical history and comprehensive omic profiling incompletely explain underlying etiologies for non-cirrhotic HCC highlighting the need for further researchShort DescriptionThis study characterizes the genomic landscape of hepatocellular carcinomas (HCCs) in non-cirrhotic livers. Using 117 HCCs tumor/normal pairs, we identified 3,750 SNVs/INDELS with high variant frequency in TERT, TP53, CTNNB1, and APOB. CYP450 was significantly downregulated and many structural variants were observed. This characterization could assist in elucidating non-cirrhotic HCC tumorigenesis.

Various stem cell markers (eg, epithelial cell adhesion molecule [EpCAM], cytokeratin 19 [K19]) have been reported as predictors of poor prognosis in hepatocellular carcinoma (HCC). However, the data remain limited, particularly in Western populations, and are often contradictory. In this study, the prognostic value of positive SOX9 immunohistochemistry was compared with that of more established markers EpCAM and K19 in a large cohort (n=216) of North American patients. The independent HCC cohort in The Cancer Gene Atlas (n=360) was utilized to validate our findings. Finally, molecular signatures associated with SOX9 -high HCC were determined. We found that the expression of SOX9, but not EpCAM or K19, was associated with worse overall survival and disease-free survival (DFS) and was an independent prognostic factor for DFS in our North American cohort, in which hepatitis C infection was the most common underlying etiology. High SOX9 mRNA level, but not increased expression of EpCAM mRNA or K19 mRNA, was also associated with worse DFS and was an independent prognostic factor for DFS in The Cancer Gene Atlas cohort. This group had underlying causes, including an increased incidence of hepatitis B, significantly different from our initial cohort. High SOX9 mRNA level is associated with molecular pathways important in HCC pathogenesis. Increased SOX9 expression is clinically and biologically relevant for HCC arising in patients with a variety of underlying etiologies. Immunohistochemistry for SOX9 is a reliable proxy for increased SOX9 mRNA and can be used to predict prognosis in HCC cases.

Background and aims Human transmembrane 6 superfamily 2 (TM6SF2) variant rs58542926 is associated with NAFLD and HCC. However, conflicting reports in germline Tm6sf2 knockout mice suggest no change or decreased very low density lipoprotein (VLDL) secretion and either unchanged or increased hepatic steatosis, with no increased fibrosis. We generated liver-specific Tm6Sf2 knockout mice (Tm6 LKO) to study VLDL secretion and the impact on development and progression of NAFLD. Approach and results Two independent lines of Tm6 LKO mice exhibited spontaneous hepatic steatosis. Targeted lipidomic analyses showed increased triglyceride species whose distribution and abundance phenocopied findings in mice with liver-specific deletion of microsomal triglyceride transfer protein. The VLDL triglyceride secretion was reduced with small, underlipidated particles and unchanged or increased apolipoprotein B. Liver-specific adeno-associated viral, serotype 8 (AAV8) rescue using either wild-type or mutant E167K-Tm6 reduced hepatic steatosis and improved VLDL secretion. The Tm6 LKO mice fed a high milk-fat diet for 3 weeks exhibited increased steatosis and fibrosis, and those phenotypes were further exacerbated when mice were fed fibrogenic, high fat/fructose diets for 20 weeks. In two models of HCC, either neonatal mice injected with streptozotocin (NASH/STAM) and high-fat fed or with diethylnitrosamine injection plus fibrogenic diet feeding, Tm6 LKO mice exhibited increased steatosis, greater tumor burden, and increased tumor area versus Tm6 flox controls. Additionally, diethylnitrosamine-injected and fibrogenic diet-fed Tm6 LKO mice administered wild-type Tm6 or E167K-mutant Tm6 AAV8 revealed significant tumor attenuation, with tumor burden inversely correlated with Tm6 protein levels. Conclusions Liver-specific Tm6sf2 deletion impairs VLDL secretion, promoting hepatic steatosis, fibrosis, and accelerated development of HCC, which was mitigated with AAV8- mediated rescue.

Non-alcoholic fatty liver disease (NAFLD), a disorder characterised by pathological accumulation of non-visible free fatty acids and visible triglyceride in hepatocytes, is on the rise globally in both adult and paediatric populations.1 Evidence suggests that 20%–50% of the European Union and US populations exhibit features of NAFLD,2 driven by higher rates of obesity, insulin resistance and type 2 diabetes, and metabolic syndrome.3 Additionally, recognition of a growing number of patients with ‘lean NAFLD’ who are not obese, but have high levels of visceral fat, diets high in fats and carbohydrates, or who have genetic risk factors, has increased.4 Of patients with NAFLD, 6%–55% will have histological signs of non-alcoholic steatohepatitis (NASH), which if left unmanaged can lead to cirrhosis and potentially hepatocellular carcinoma.5 NAFLD has surpassed viral hepatitis as the leading cause of chronic liver disease worldwide.6 Estimates suggest that by 2030 NAFLD will overtake hepatitis C as the primary cause of liver failure requiring transplantation and that the number of NAFLD-related deaths will increase by 178%.7 Annual spending related to NAFLD care is estimated to rise exponentially from $103 billion to $1.005 trillion in the USA and from €35 billion to €334 billion in Europe between 2016 and 2025.8 While bariatric surgery and/or weight loss can be effective, they present their own challenges in delivery. There are presently no approved drugs on the market; hence, the number of clinical trials has grown by approximately 60% over the last 10 years. As both the Food and Drug Administration and the European Medicines Agency require liver biopsy for clinical trials as the ‘gold standard’, diagnosis and monitoring rely on pathological assessment of a liver biopsy.9–11 Most trials focus only on the numerically reported values of the semiquantitative assessment of four cardinal features of NAFLD/NASH—steatosis, inflammation, hepatocellular ballooning …

The role of liver biopsy in nonalcoholic steatohepatitis (NASH) has evolved along with the increased recognition of the significance of this disease, and the unmet medical need it presents. Drug development and clinical trials are rapidly growing, as are non-invasive tests for markers of steatosis, inflammation, injury and fibrosis. Liver biopsy evaluation remains necessary for both drug development and clinical trials as the most specific means of diagnosis and patient identification for appropriate intervention. This White Paper, sponsored by the American Association for the Study of Liver Disease NASH Task Force, is a focused review of liver biopsy evaluation in fatty liver disease in subjects with presumed NAFLD for practicing clinical hepatologists and pathologists. The goal is to provide succinct and specific means for reporting the histopathologic elements of NASH, distinguishing NASH from nonalcoholic fatty liver without steatohepatitis (NAFL), and from alcoholic steatohepatitis when possible. The discussion includes the special situations of NASH in advanced fibrosisor cirrhosis, and in the pediatric population. Finally, there is discussion of semiquantitative methods of evaluation of lesions of "disease activity" and fibrosis. Tables are present for scoring and a suggested model for final reporting. Figures presented highlight the histopathologic elements of NASH.

Professional societies play a major role in medicine and science. The societies tend to be large with well-developed administrative structures. An additional model, however, is based on small groups of experts who meet regularly in an egalitarian model in order to discuss disease-specific scientific and medical problems. In order to illustrate the effectiveness of this model, the history and practices are examined of a long-standing successful example, the International Liver Pathology Group, better known as the Gnomes. The history shows that groups such as the Gnomes offer a number of important benefits not available in larger societies and nurturing such groups advances science and medicine in meaningful ways. The success of the Gnomes’ approach provides a road map for future small scientific groups. Electronic supplementary material The online version of this article (10.1007/s00428-020-02879-5) contains supplementary material, which is available to authorized users.

No consensus criteria or approach exist regarding assessment of steatosis in the setting of human donor liver suitability for transplantation. The Banff Working Group on Liver Allograft Pathology undertook a study to determine the consistency with which steatosis is assessed and reported in frozen sections of potential donor livers. A panel of 59 pathologists from 16 countries completed a questionnaire covering criteria used to assess steatosis in donor liver biopsies, including droplet size and magnification used; subsequently, steatosis severity was assessed in 18 whole slide images of donor liver frozen sections (n=59). Survey results (from 56/59) indicated a wide variation in definitions and approaches used to assess and report steatosis. Whole slide image assessment led to a broad range in the scores. Findings were discussed at a workshop held at the 15th Banff Conference on Allograft Pathology, September 2019. The aims of discussions were to (i) establish consensus criteria for defining "large droplet fat" (LDF) that predisposes to increased risk of initial poor graft function; and (ii) develop an algorithmic approach to determine fat droplet size, and the percentage of hepatocytes involved. Large droplet fat was defined as typically a single fat droplet that expands the involved hepatocyte and is larger than adjacent non-steatotic hepatocytes. Estimating severity of steatosis involves (i) low magnification estimate of the approximate surface area of the biopsy occupied by fat, (ii) higher magnification determination of the percentage of hepatocytes within the fatty area with large droplet fat and (iii) final score calculation. The proposed guidelines herein are intended to improve standardization in steatosis assessment of donor liver biopsies. The calculated percent LDF should be provided to the surgeon.

Histologically assessed hepatocyte ballooning is a key feature discriminating non-alcoholic steatohepatitis (NASH) from steatosis (NAFL). Reliable identification underpins patient inclusion in clinical trials and serves as a key regulatory-approved surrogate endpoint for drug efficacy. High inter/intra-observer variation in ballooning measured using the NASH CRN semi-quantitative score has been reported yet no actionable solutions have been proposed.A focused evaluation of hepatocyte ballooning recognition was conducted. Digitized slides were evaluated by 9 internationally recognized expert liver pathologists on 2 separate occasions: each pathologist independently marked every ballooned hepatocyte and later provided an overall non-NASH NAFL/NASH assessment. Interobserver variation was assessed and a 'concordance atlas' of ballooned hepatocytes generated to train second harmonic generation/two-photon excitation fluorescence imaging-based artificial intelligence (AI).The Fleiss kappa statistic for overall interobserver agreement for presence/absence of ballooning was 0.197 (95% CI 0.094-0.300), rising to 0.362 (0.258-0.465) with a ≥5-cell threshold. However, the intraclass correlation coefficient for consistency was higher (0.718 [0.511-0.900]), indicating 'moderate' agreement on ballooning burden. 133 ballooned cells were identified using a ≥5/9 majority to train AI ballooning detection (AI-pathologist pairwise concordance 19-42%, comparable to inter-pathologist pairwise concordance of between 8-75%). AI quantified change in ballooned cell burden in response to therapy in a separate slide set.The substantial divergence in hepatocyte ballooning identified amongst expert hepatopathologists suggests that ballooning is a spectrum, too subjective for its presence or complete absence to be unequivocally determined as a trial endpoint. A concordance atlas may be used to train AI assistive technologies to reproducibly quantify ballooned hepatocytes that standardize assessment of therapeutic efficacy. This atlas serves as a reference standard for ongoing work to refine how ballooning is classified by both pathologists and AI.For the first time, we show that, even amongst expert hepatopathologists, there is poor agreement regarding the number of ballooned hepatocytes seen on the same digitized histology images. This has important implications as the presence of ballooning is needed to establish the diagnosis of non-alcoholic steatohepatitis (NASH), and its unequivocal absence is one of the key requirements to show 'NASH resolution' to support drug efficacy in clinical trials. Artificial intelligence-based approaches may provide a more reliable way to assess the range of injury recorded as "hepatocyte ballooning".

Non-alcoholic fatty liver disease (NAFLD) affects approximately 8 million Canadians. NAFLD refers to a disease spectrum ranging from bland steatosis to non-alcoholic steatohepatitis (NASH). Nearly 25% of patients with NAFLD develop NASH, which can progress to liver cirrhosis and related end-stage complications. Type 2 diabetes and obesity represent the main risk factors for the disease. The Canadian NASH Network is a national collaborative organization of health care professionals and researchers with a primary interest in enhancing understanding, care, education, and research around NAFLD, with a vision of best practices for this disease state. At the 1st International Workshop of the CanNASH network in April 2021, a joint event with the single topic conference of the Canadian Association for the Study of the Liver (CASL), clinicians, epidemiologists, basic scientists, and community members came together to share their work under the theme of NASH. This symposium also marked the initiation of collaborations between Canadian and other key opinion leaders in the field representative of international liver associations. The main objective is to develop a policy framework that outlines specific targets, suggested activities, and evidence-based best practices to guide provincial, territorial, and federal organizations in developing multidisciplinary models of care and strategies to address this epidemic.

Regulating dietary fat absorption may impact progression of nonalcoholic fatty liver disease (NAFLD). Here, we asked if inducible inhibition of chylomicron assembly, as observed in intestine-specific microsomal triglyceride (TG) transfer protein knockout mice (Mttp-IKO), could retard NAFLD progression and/or reverse established fibrosis in two dietary models. Mttp-IKO mice fed a methionine/choline-deficient (MCD) diet exhibited reduced hepatic TGs, inflammation, and fibrosis, associated with reduced oxidative stress and downstream activation of c-Jun N-terminal kinase and nuclear factor kappa B signaling pathways. However, when Mttpflox mice were fed an MCD for 5 weeks and then administered tamoxifen to induce Mttp-IKO, hepatic TG was reduced, but inflammation and fibrosis were increased after 10 days of reversal along with adaptive changes in hepatic lipogenic mRNAs. Extending the reversal time, following 5 weeks of MCD feeding to 30 days led to sustained reductions in hepatic TG, but neither inflammation nor fibrosis was decreased, and both intestinal permeability and hepatic lipogenesis were increased. In a second model, similar reductions in hepatic TG were observed when mice were fed a high-fat/high-fructose/high-cholesterol (HFFC) diet for 10 weeks, then switched to chow ± tamoxifen (HFFC → chow) or (HFFC → Mttp-IKO chow), but again neither inflammation nor fibrosis was affected. In conclusion, we found that blocking chylomicron assembly attenuates MCD-induced NAFLD progression by reducing steatosis, oxidative stress, and inflammation. In contrast, blocking chylomicron assembly in the setting of established hepatic steatosis and fibrosis caused increased intestinal permeability and compensatory shifts in hepatic lipogenesis that mitigate resolution of inflammation and fibrogenic signaling despite 50–90-fold reductions in hepatic TG.

Hepatocellular injury and inflammation are believed to be the primary drivers of fibrogenesis that ultimately lead to cirrhosis in patients with nonalcoholic steatohepatitis (NASH). This study sought associations between observed improvements in fibrosis with improvement in specific histologic features, nonalcoholic fatty liver disease activity score (NAS) ≥2, diagnostic category, and primary histologically based outcomes of two adult NASH treatment trials. The primary outcome for the study was fibrosis improvement from baseline to end of treatment, defined as a 1-point or more improvement in fibrosis stage. This is a retrospective analysis of biopsy data collected from the NASH Clinical Research Network Pathology Committee of Pioglitazone versus Vitamin E versus Placebo for the Treatment of Nondiabetic Patients with NASH Trial (PIVENS) and Farnesoid X Receptor Ligand Obeticholic Acid in NASH Treatment Trial (FLINT) baseline and final biopsies. Treatment group-adjusted univariable and multivariable logistic regression models related improvement in fibrosis to improvements in other histologic variables, resolution of steatohepatitis, and improvement in the NAS ≥2. In PIVENS 221 subjects had baseline and 96-week biopsies, and in FLINT 200 subjects had baseline and 72-week biopsies. Improvement in fibrosis was found in 38% of PIVENS and 29% of FLINT biopsies; fibrosis improvement was more likely in treated than placebo subjects in both studies. Controlling for treatment group, fibrosis improvement was associated most strongly with resolution of NASH (PIVENS, odds ratio [OR], 3.9; 95% confidence interval [CI] 2.0-7.6; P < 0.001; FLINT, OR, 8.0; 95% CI 3.1-20.9; P < 0.001), and improved NAS by ≥2 (PIVENS, OR, 2.4; 95% CI 1.3-4.3; P = 0.003; FLINT, OR, 4.2; 95% CI 2.1-8.3; P < 0.001). Improvement in histologic features associated with improved fibrosis for both studies included steatosis, ballooning, Mallory-Denk bodies, and portal, but not lobular, inflammation. Conclusion: These findings support a strong link between histologic resolution of steatohepatitis with improvement in fibrosis in NASH.

Despite the substantial gains in our understanding of NAFLD/NASH over the past 2 decades, there has been some dissatisfaction with the terminology "non-alcoholic" which overemphasizes "alcohol" and underemphasizes the root cause of this liver disease, namely, the predisposing metabolic risk factors. As a potential remedy, a name change from NAFLD to metabolic associated fatty liver disease (MAFLD) has been proposed. Although MAFLD reflects the relevant risk factors for this liver disease, this term is still suboptimal, leaving a great deal of ambiguity. Here, we caution that changing the name without understanding its broad implications can have a negative impact on the field. In this context, changing the terminology without new understanding of the molecular basis of the disease entity, new insights in risk stratification or other important aspect of this liver disease, can create unnecessary confusion which could negatively impact the field. At a time when the field is facing substantial challenges around disease awareness as well as clarity of acceptable endpoints for drug development and biomarker discovery, changing the terminology from one suboptimal name to another suboptimal name without full assessment is expected to deepen these challenges. In the context of this debate about terminology, we recommend the creation of a true international consensus group to include all the relevant scientific liver societies (AASLD, EASL, ALEH, APASL), patient advocacy organizations, bio-pharmaceutical industry, regulatory agencies and policy makers. A consensus meeting must assess the impact and consequences of changing the terminology based on the available evidence and make recommendations that will move the field forward. By this approach, a true collaborative international and inclusive consensus can be adopted by all stakeholders dealing with this important global liver disease.

Background Pathologist evaluation of donor liver biopsies provides information for accepting or discarding potential donor livers. Due to the urgent nature of the decision process, this is regularly performed using frozen sectioning at the time of biopsy. The percent steatosis in a donor liver biopsy correlates with transplant outcome, however there is significant inter- and intra-observer variability in quantifying steatosis, compounded by frozen section artifact. We hypothesized that a deep learning model could identify and quantify steatosis in donor liver biopsies. Methods We developed a deep learning convolutional neural network that generates a steatosis probability map from an input whole slide image (WSI) of a hematoxylin and eosin-stained frozen section, and subsequently calculates the percent steatosis. Ninety-six WSI of frozen donor liver sections from our transplant pathology service were annotated for steatosis and used to train (n = 30 WSI) and test (n = 66 WSI) the deep learning model. Findings The model had good correlation and agreement with the annotation in both the training set (r of 0.88, intraclass correlation coefficient [ICC] of 0.88) and novel input test sets (r = 0.85 and ICC=0.85). These measurements were superior to the estimates of the on-service pathologist at the time of initial evaluation (r = 0.52 and ICC=0.52 for the training set, and r = 0.74 and ICC=0.72 for the test set). Interpretation Use of this deep learning algorithm could be incorporated into routine pathology workflows for fast, accurate, and reproducible donor liver evaluation. Funding Mid-America Transplant Society

Background: Combined hepatocellular-cholangiocarcinoma tumors (cHCC-CCA) are a heterogeneous group of rare malignancies that have no established optimal treatment. Patients and Methods: We identified patients with cHCC-CCA treated at a tertiary center and retrospectively examined their histology, interventions, and outcomes. We calculated disease control rate (DCR), disease progression, overall survival, and progression-free survival (PFS) between treatment subgroups. Results: A total of 123 patients were evaluable. Interventions included resection, locoregional therapy, transplant, chemotherapy, and targeted agents. Ultimately, 68 patients received systemic treatment-57 with gemcitabine plus either 5-fluoropyrimidine (5-FU) or a platinum combination. Disease progression was more common in the gemcitabine/5-FU group versus gemcitabine/platinum (P=.028), whereas DCR favored gemcitabine/platinum (78.4% vs 38.5%; P=.0143). Median PFS from time of initial diagnosis favored the gemcitabine/platinum group, but the difference did not reach statistical significance. Targeted agents had minimal to no effect on survival metrics. Conclusions: Gemcitabine/platinum seems to be a superior regimen for patients with cHCC-CCA who require systemic treatment. Further studies are needed to clarify the regimen's efficacy and applicability in patient subgroups.

Author(s): Brunt, Elizabeth; Aishima, Shinichi; Clavien, Pierre-Alain; Fowler, Kathryn; Goodman, Zachary; Gores, Gregory; Gouw, Annette; Kagen, Alex; Klimstra, David; Komuta, Mina; Kondo, Fukuo; Miksad, Rebecca; Nakano, Masayuki; Nakanuma, Yasuni; Ng, Irene; Paradis, Valerie; Nyun Park, Young; Quaglia, Alberto; Roncalli, Massimo; Roskams, Tania; Sakamoto, Michiie; Saxena, Romil; Sempoux, Christine; Sirlin, Claude; Stueck, Ashley; Thung, Swan; Tsui, WMS; Wang, Xin-Wei; Wee, Aileen; Yano, Hirohisa; Yeh, Matthew; Zen, Yoh; Zucman-Rossi, Jessica; Theise, Neil | Abstract: Primary liver carcinomas with both hepatocytic and cholangiocytic differentiation have been referred to as "combined (or mixed) hepatocellular-cholangiocarcinoma." These tumors, although described over 100 years ago, have attracted greater attention recently because of interest in possible stem cell origin and perhaps because of greater frequency and clinical recognition. Currently, because of a lack of common terminology in the literature, effective treatment and predictable outcome data have been challenging to accrue. This article represents a consensus document from an international community of pathologists, radiologists, and clinicians who have studied and reported on these tumors and recommends a working terminology for diagnostic and research approaches for further study and evaluation.ConclusionIt is recommended that diagnosis is based on routine histopathology with hematoxylin and eosin (HaE); immunostains are supportive, but not essential for diagnosis. (Hepatology 2018;68:113-126).

Author(s): Middleton, Michael S; Van Natta, Mark L; Heba, Elhamy R; Alazraki, Adina; Trout, Andrew T; Masand, Prakash; Brunt, Elizabeth M; Kleiner, David E; Doo, Edward; Tonascia, James; Lavine, Joel E; Shen, Wei; Hamilton, Gavin; Schwimmer, Jeffrey B; Sirlin, Claude B; NASH Clinical Research Network | Abstract: We assessed the performance of magnetic resonance imaging (MRI) proton density fat fraction (PDFF) in children to stratify hepatic steatosis grade before and after treatment in the Cysteamine Bitartrate Delayed-Release for the Treatment of Nonalcoholic Fatty Liver Disease in Children (CyNCh) trial, using centrally scored histology as reference. Participants had multiecho 1.5 Tesla (T) or 3T MRI on scanners from three manufacturers. Of 169 enrolled children, 110 (65%) and 83 (49%) had MRI and liver biopsy at baseline and at end of treatment (EOT; 52 weeks), respectively. At baseline, 17% (19 of 110), 28% (31 of 110), and 55% (60 of 110) of liver biopsies showed grades 1, 2, and 3 histological steatosis; corresponding PDFF (meann±nSD) values were 10.9n±n4.1%, 18.4n±n6.2%, and 25.7n±n9.7%, respectively. PDFF classified grade 1 versus 2-3 and 1-2 versus 3 steatosis with areas under receiving operator characteristic curves (AUROCs) of 0.87 (95% confidence interval [CI], 0.80, 0.94) and 0.79 (0.70, 0.87), respectively. PDFF cutoffs at 90% specificity were 17.5% for grades 2-3 steatosis and 23.3% for grade 3 steatosis. At EOT, 47% (39 of 83), 41% (34 of 83), and 12% (10 of 83) of biopsies showed improved, unchanged, and worsened steatosis grade, respectively, with corresponding PDFF (meann±nSD) changes of -7.8n±n6.3%, -1.2n±n7.8%, and 4.9n±n5.0%, respectively. PDFF change classified steatosis grade improvement and worsening with AUROCs (95% CIs) of 0.76 (0.66, 0.87) and 0.83 (0.73, 0.92), respectively. PDFF change cut-off values at 90% specificity were -11.0% and +5.5% for improvement and worsening.ConclusionMRI-estimated PDFF has high diagnostic accuracy to both classify and predict histological steatosis grade and change in histological steatosis grade in children with NAFLD. (Hepatology 2018;67:858-872).

Nonalcoholic fatty liver disease (NAFLD) is one of the most common underlying causes of chronically elevated liver tests and liver disease in adults and children worldwide and may be strongly suspected if not diagnosed by ever evolving and available serologic and imaging-based noninvasive tests. However, the definitive diagnosis of the most progressive form of NAFLD, nonalcoholic steatohepatitis, and the identification of fibrosis stage still require liver biopsy evaluation as noninvasive testing has not replaced some of the specifics or the totality of information obtainable from liver biopsy. In this review, both the role and value of a liver biopsy evaluation in NAFLD/ nonalcoholic steatohepatitis are examined from publications related to a selected variety of settings. Details of the most commonly used semiquantitative methods of analysis are discussed, and some useful potential pitfalls for differential diagnostic consideration in liver biopsy interpretation are given. (Hepatology Communications 2017;1:370-378).

Diseases of the liver related to metabolic syndrome have emerged as the most common and undertreated hepatic ailments. The cause of nonalcoholic fatty liver disease is the aberrant accumulation of lipid in hepatocytes, though the mechanisms whereby this leads to hepatocyte dysfunction, death, and hepatic fibrosis are still unclear. Insulin-sensitizing thiazolidinediones have shown efficacy in treating nonalcoholic steatohepatitis (NASH), but their widespread use is constrained by dose-limiting side effects thought to be due to activation of the peroxisome proliferator–activated receptor γ. We sought to determine whether a next-generation thiazolidinedione with markedly diminished ability to activate peroxisome proliferator–activated receptor γ (MSDC-0602) would retain its efficacy for treating NASH in a rodent model. We also determined whether some or all of these beneficial effects would be mediated through an inhibitory interaction with the mitochondrial pyruvate carrier 2 (MPC2), which was recently identified as a mitochondrial binding site for thiazolidinediones, including MSDC-0602. We found that MSDC-0602 prevented and reversed liver fibrosis and suppressed expression of markers of stellate cell activation in livers of mice fed a diet rich in trans-fatty acids, fructose, and cholesterol. Moreover, mice with liver-specific deletion of MPC2 were protected from development of NASH on this diet. Finally, MSDC-0602 directly reduced hepatic stellate cell activation in vitro, and MSDC-0602 treatment or hepatocyte MPC2 deletion also limited stellate cell activation indirectly by affecting secretion of exosomes from hepatocytes. Conclusion: Collectively, these data demonstrate the effectiveness of MSDC-0602 for attenuating NASH in a rodent model and suggest that targeting hepatic MPC2 may be an effective strategy for pharmacologic development. (Hepatology 2017;65:1543-1556).

Key Points Question In patients with nonalcoholic fatty liver disease who are not undergoing specific therapeutic interventions, what factors are associated with progression and regression of hepatic fibrosis? Findings In this cohort study of 446 patients, high baseline nonalcoholic fatty liver disease activity score and changes in the score were associated with concordant changes in fibrosis. Weight gain, high baseline aspartate aminotransferase level, and increases in the aspartate aminotransferase level were associated with fibrosis progression. Meaning These data may support the use of therapeutics targeting disease activity in nonalcoholic steatohepatitis and the use of short-term changes in the nonalcoholic fatty liver disease activity score as an end point in such clinical trials; in clinical practice, weight gain and an increasing aspartate aminotransferase level should increase suspicion of increasing fibrosis., Importance The histologic evolution of the full spectrum of nonalcoholic fatty liver disease (NAFLD) and factors associated with progression or regression remain to be definitively established. Objective To evaluate the histologic evolution of NAFLD and the factors associated with changes in disease severity over time. Design, Setting, and Participants A prospective cohort substudy from the Nonalcoholic Steatohepatitis Clinical Research Network (NASH CRN) NAFLD Database study, a noninterventional registry, was performed at 8 university medical research centers. Masked assessment of liver histologic specimens was performed, using a prespecified protocol to score individual biopsies. Participants included 446 adults with NAFLD enrolled in the NASH CRN Database studies between October 27, 2004, and September 13, 2013, who underwent 2 liver biopsies 1 or more year apart. Data analysis was performed from October 2016 to October 2018. Main Outcomes and Measures Progression and regression of fibrosis stage, using clinical, laboratory, and histologic findings, including the NAFLD activity score (NAS) (sum of scores for steatosis, lobular inflammation, and ballooning; range, 0-8, with 8 indicating more severe disease). Results A total of 446 adults (mean [SD] age, 47 [11] years; 294 [65.9%] women) with NAFLD (NAFL, 86 [19.3%]), borderline NASH (84 [18.8%]), and definite NASH (276 [61.9%]) were studied. Over a mean (SD) interval of 4.9 (2.8) years between biopsies, NAFL resolved in 11 patients (12.8%) and progressed to steatohepatitis in 36 patients (41.9%). Steatohepatitis resolved in 24 (28.6%) of the patients with borderline NASH and 61 (22.1%) of those with definite NASH. Fibrosis progression or regression by at least 1 stage occurred in 132 (30%) and 151 [34%] participants, respectively. Metabolic syndrome (20 [95%] vs 108 [72%]; P = .03), baseline NAS (mean [SD], 5.0 [1.4] vs 4.3 [1.6]; P = .005), and smaller reduction in NAS (−0.2 [2] vs −0.9 [2]; P, This cohort study evaluates the progression and regression of hepatic fibrosis over time in association with the severity of nonalcoholic fatty liver disease.

BACKGROUND & AIMS: Nonalcoholic fatty liver disease (NAFLD) is the most common pediatric chronic liver disease. Little is known about outcomes in recognized youth. METHODS: We compared paired liver biopsies from 122 of 139 children with NAFLD (74% male; 64% white; 71% Hispanic; mean age, 13 ± 3 years; age range, 8–17 years) who received placebo and standard of care lifestyle advice in 2 double-blind, randomized clinical trials within the nonalcoholic steatohepatitis (NASH) clinical research network from 2005 through 2015. We analyzed histologic changes with respect to baseline and longitudinal change in clinical variables using regression analysis. RESULTS: At enrollment, 31% of the children had definite NASH, 34% had borderline zone 1 NASH, 13% had borderline zone 3 NASH, and 21% had fatty liver but not NASH. Over a mean period of 1.6 ± 0.4 years, borderline or definite NASH resolved in 29% of the children, whereas 18% of the children with fatty liver or borderline NASH developed definite NASH. Fibrosis improved in 34% of the children but worsened in 23%. Any progression to definite NASH or in fibrosis occurred in 36% of the children, and both occurred in 11% of the children. Any improvement in NASH or fibrosis occurred in 52%, and both occurred in 20% of children. Type 2 diabetes developed in 5% of the cohort. Any progression to NASH and/or fibrosis was associated with adolescent age, higher waist circumference, levels of alanine or aspartate aminotransferase, total and low-density lipoprotein-cholesterol at baseline, increasing level of alanine aminotransferase, and hemoglobin A1C (P < .05). Progression to NASH and/or fibrosis were also associated with increasing level of gamma-glutamyl transferase and development of type 2 diabetes (P < .01). Increasing level of gamma-glutamyl transferase also associated with reduced odds of any improvement (P = .003). CONCLUSIONS: One-third of children with NAFLD enrolled in placebo groups of clinical trials had histologic features of progression within 2 years, in association with increasing obesity and serum levels of aminotransferases and loss of glucose homeostasis.

Characteristic but rare vascular neoplasms in the adult liver composed of small vessels with an infiltrative border were collected from an international group of collaborators over a 5-year period (N = 17). These tumors were termed hepatic small vessel neoplasm (HSVN), and the histologic differential diagnosis was angiosarcoma (AS). The average age of patients was 54 years (range, 24–83 years). HSVN was more common in men. The average size was 2.1 cm (range, 0.2–5.5 cm). Diagnosis was aided by immunohistochemical stains for vascular lineage (CD31, CD34, FLI-1), which were uniformly positive in HSVN. Immunohistochemical stains (p53, c-Myc, GLUT-1, and Ki-67) for possible malignant potential are suggestive of a benign/low-grade tumor. Capture-based next-generation sequencing (using an assay that targets the coding regions of more than 500 cancer genes) identified an activating hotspot GNAQ mutation in 2 of 3 (67%) tested samples, and one of these cases also had a hotspot mutation in PIK3CA. When compared with hepatic AS (n = 10) and cavernous hemangioma (n = 6), the Ki-67 proliferative index is the most helpful tool in excluding AS, which demonstrated a tumor cell proliferative index greater than 10% in all cases. Strong p53 and diffuse c-Myc staining was also significantly associated with AS but not with HSVN or cavernous hemangioma. There have been no cases with rupture/hemorrhage, disseminated intravascular coagulation, or Kasabach-Merritt syndrome. Thus far, there has been no metastasis or recurrence of HSVN, but complete resection and close clinical follow-up are recommended because the outcome remains unknown.

The purpose of this study was to determine the frequency with which biphenotypic primary liver carcinoma (also called hepatocholangiocarcinoma) may be misclassified as hepatocellular carcinoma (HCC) when only Liver Imaging Reporting and Data System (LI-RADS) major features are used and after consideration of ancillary features.A review of all pathologically proven biphenotypic primary liver carcinomas diagnosed at one institution from 2006 to 2014 was performed. Two subspecialized abdominal imagers independently reviewed cases using LI-RADS version 2014 and assigned major features, ancillary features, and additional findings. The number of lesions meeting imaging criteria for HCC was determined after assessment of major features alone and after the addition of ancillary features.Sixty-one patients (30 men, 31 women; mean age, 62 years; range, 22-89 years) with biphenotypic primary liver carcinomas who underwent pretreatment multiphasic contrast-enhanced MRI (48 patients) or CT (13 patients) were included. According to LI-RADS major features alone, 33 (54.1%) lesions met criteria for HCC and therefore might have been misclassified. Thirteen had arterial phase hyperenhancement, washout, and a capsule. Twenty had arterial phase hyperenhancement with either washout (15 lesions) or a capsule (five lesions). After evaluation of ancillary features, 29 of these potential mimics exhibited at least one ancillary feature favoring non-HCC malignancy, possibly leading to appropriate reclassification. Of the four carcinomas that met criteria for HCC by major features and did not have ancillary features favoring non-HCC malignancy, two (3.3% of all tumors) fell within the Milan criteria.Most biphenotypic primary liver carcinomas have features of non-HCC malignancy and can be correctly categorized as such. Addition of ancillary features to major features may improve diagnostic accuracy over systems in which only major features are used.

The significance of the quantity of acidophil bodies (AB) in nonalcoholic steatohepatitis (NASH) is not certain. We quantified AB in liver biopsies and examined the association with the diagnosis of NASH and other histologic features. We reviewed 157 liver biopsies from the NASH Clinical Research Network Database collected in 2006. One hundred twenty-seven biopsies were from adult patients. Diagnoses were 94 definite NASH, 40 borderline NASH, and 23 definitely not NASH. The total length and average width of the core biopsies were measured, and the biopsy areas were calculated (mm(2)). Total AB were counted, and mean AB count per mm(2) was calculated (AB/mm(2)) to derive acidophil body index (ABI). ABI was 0.04 (±0.08) in definite NASH and 0.02 (±0.05) in borderline/definitely not NASH groups combined (P = .02) in all 157 biopsies; similar findings were present in the 127 adult-only biopsies (0.04 ± 0.05 and 0.02 ± 0.05, respectively; P = .05). In all 157 biopsies, increased ABI was associated with greater lobular inflammation (P = .01) and many ballooned hepatocytes (P = .048). There was a positive relationship between ABI and high nonalcoholic fatty liver disease activity scores, but this association was not statistically significant. There was no association between ABI and steatosis or fibrosis stage either in the entire cohorts or in the subset of adult patients. In conclusion, the density of AB is associated with lobular inflammation, ballooned hepatocytes, and the diagnosis of NASH in adult and pediatric liver biopsies, suggesting the implication of the apoptotic pathway in NASH-associated liver cell injury.

The aim of the present study was to examine the association between plasminogen activator inhibitor-1 (PAI-1), an acute phase protein strongly associated with cardiovascular disease risk, and adiposity, insulin resistance, and inflammation among overweight and obese children with a wide range of hepatic steatosis.Plasma PAI-1 levels were measured in a prospectively recruited cohort of 39 overweight or obese children who underwent comprehensive anthropometric assessment and metabolic measurements. Hepatic steatosis was quantified using magnetic resonance spectroscopy and participants were divided into 3 groups based on whether they had normal hepatic steatosis (5%), low hepatic steatosis (≥5%-10%), and high hepatic steatosis (10%).Plasma PAI-1 levels significantly increased across the severity of hepatic steatosis in overweight and obese children, and this association was independent of body mass index z score, visceral fat, insulin resistance, and inflammatory markers (P 0.05).Hepatic steatosis in children is positively associated with circulating levels of PAI-1 independent of body mass index, insulin resistance, and inflammatory markers. Further studies are needed to clarify the potential role of PAI-1 as a therapeutic target in pediatric nonalcoholic fatty liver disease.

Aims Subtle lesions of terminal hepatic venules (THVs) may be overlooked in liver biopsies from haematopoietic stem cell transplant (HSCT) receipients when graft-versus-host disease is the clinical concern. The aim of this study was to evaluate the frequency of THV injury resembling sinusoidal obstruction syndrome (SOS). Methods and results Sixty-three consecutive biopsies from allogeneic HSCT recipients were scored for injured THVs. Forty-nine (78%) biopsies had injured THVs, and 10 (16%) were diagnosed with SOS (mean ± standard deviation of injured THVs/biopsy: 90 ± 9%). Biopsies diagnosed with other diseases also had injured THVs (36 ± 33%). Biopsies from patients with cyclophosphamide plus fractionated total body irradiation conditioning and biopsies taken within 100 days post-HSCT had significantly more occluded THVs (respectively: 40 ± 38%, P = 0.0188; and 35 ± 35%, P = 0.0076) than those with other conditioning regimens or in biopsies taken >100 days post-HSCT. All biopsies taken at any time in the 6-year post-HSCT period had similar amounts of THV phlebosclerosis (23 ± 25%). Conclusions Our results demonstrate a high incidence of THV injuries resembling SOS in post-HSCT liver biopsies. THV injuries were detectable for several years post-HSCT, and were concurrent with other diagnoses. Our results also suggest that SOS may be underdiagnosed.

Biphenotypic (hepatobiliary) primary liver carcinomas [B(H-B)PLCs] are rare tumors with features of both hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC). These tumors are associated with a poor overall prognosis and treatment is not well defined. Research over the past 20 years has identified aberrations in several molecular pathways, including epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) in hepatocellular and biliary tract cancers. These discoveries led to the evaluation of targeted therapies, such as tyrosine kinase inhibitors, for the treatment of HCC and ICC. We report a case of a patient with metastatic B(H-B)PLC found to have a single nucleotide variant in the EGFR gene locus R521K who achieved a complete response on imaging after treatment with the combination of an EGFR inhibitor and a VEGF inhibitor. This case prompts consideration of further genomic analysis of these rare tumors and the potential use of targeted therapies in the treatment of patients with B(H-B)PLCs.

Hepatic small vessel neoplasm (HSVN) is a recently described infiltrative vascular neoplasm of the liver, composed of small vessels. Although the infiltrative nature can mimic angiosarcoma, HSVN are thought to be benign or low-grade neoplasms because they lack cytologic atypia and increased proliferation. To characterize the molecular pathogenesis of HSVN, we performed both targeted panel sequencing and exome sequencing on 18 benign or low-grade vascular neoplasms in the liver including 8 HSVN, 6 classic cavernous hemangioma (CH), and 4 variant lesions (VL) with overlapping features between HSVN and CH. All 18 lesions had simple genomes without copy number alterations. In total, 75% (6/8) of HSVN demonstrated known activating hotspot mutations in GNAQ (2/8, p.Q209H) or GNA14 (4/8, p.Q205L), and the remaining 2 had the same missense mutation in GNAQ, p.G48L, which has not been previously described. 25% (1/4) of VL had a hotspot GNAQ p.Q209H mutation and another VL had a GNAQ p.G48L mutation. Known pathogenic mutations were not identified in any of the 6 CH. These data suggest that HSVN share a similar molecular biology to several other vascular lesions (congenital hemangioma, tufted angioma, anastomosing hemangioma, lobular capillary hemangioma, and kaposiform hemangioendothelioma) recently reported to have GNAQ, GNA11, or GNA14 mutations.

BACKGROUND AND OBJECTIVES: Nonalcoholic fatty liver disease (NAFLD) disproportionately affects Hispanic boys. Further, obesity and insulin resistance are major risk factors for NAFLD. No gene localization studies had been performed on children with biopsy-proven NAFLD. This study aims to identify genomic variants associated with increased adiposity and insulin resistance in a population of children with varying histologic severity of NAFLD. METHODS: We conducted a genome-wide association scan (GWAS) including 624,297 single nucleotide polymorphisms (SNPs) distributed among all 22 autosomal chromosomes in 234 Hispanic boys (up to 18 years of age) who were consecutively recruited in a prospective cohort study in the Nonalcoholic Steatohepatitis Clinical Research Network Studies. Traits were examined quantitatively using linear regression. SNPs with p-value 5% were considered potentially significant. RESULTS: Evaluated subjects had a median age of 12.0 years, BMI of 31.4, and hemoglobin A1C (Hgb A1C) of 5.3. The prevalence of NAFL, borderline NASH and definite NASH were 23%, 53%, and 22%, respectively. The GWAS identified 10 SNPs that were associated with BMI z-score, 6 within chromosome 2, and 1 within CAMK1D, which has a potential role in liver gluconeogenesis. In addition, the GWAS identified 9 novel variants associated with insulin resistance: HOMA-IR (6) and HbA1c (3). CONCLUSIONS: This study of Hispanic boys with biopsy-proven NAFLD with increased risk for the metabolic syndrome revealed novel genetic variants that are associated with obesity and insulin resistance.

Objective To identify genetic loci associated with features of histologic severity of nonalcoholic fatty liver disease in a cohort of Hispanic boys. Study design There were 234 eligible Hispanic boys age 2-17 years with clinical, laboratory, and histologic data enrolled in the Nonalcoholic Steatohepatitis Clinical Research Network included in the analysis of 624 297 single nucleotide polymorphisms (SNPs). After the elimination of 4 outliers and 22 boys with cryptic relatedness, association analyses were performed on 208 DNA samples with corresponding liver histology. Logistic regression analyses were carried out for qualitative traits and linear regression analyses were applied for quantitative traits. Results The median age and body mass index z-score were 12.0 years (IQR, 11.0-14.0) and 2.4 (IQR, 2.1-2.6), respectively. The nonalcoholic fatty liver disease activity score (scores 1-4 vs 5-8) was associated with SNP rs11166927 on chromosome 8 in the TRAPPC9 region (P = 8.7-07). Fibrosis stage was associated with SNP rs6128907 on chromosome 20, near actin related protein 5 homolog (p = 9.9-07). In comparing our results in Hispanic boys with those of previously reported SNPs in adult nonalcoholic steatohepatitis, 2 of 26 susceptibility loci were associated with nonalcoholic fatty liver disease activity score and 2 were associated with fibrosis stage. Conclusions In this discovery genome-wide association study, we found significant novel gene effects on histologic traits associated with nonalcoholic fatty liver disease activity score and fibrosis that are distinct from those previously recognized by adult nonalcoholic fatty liver disease genome-wide association studies.

Magnetic resonance elastography (MRE) is a promising technique for noninvasive assessment of fibrosis, a major determinant of outcome in nonalcoholic fatty liver disease (NAFLD). However, data in children are limited. The purpose of this study was to determine the accuracy of MRE for the detection of fibrosis and advanced fibrosis in children with NAFLD and to assess agreement between manual and novel automated reading methods. We performed a prospective, multicenter study of two-dimensional (2D) MRE in children with NAFLD. MR elastograms were analyzed manually at two reading centers, and using a new automated technique. Analysis using each approach was done independently. Correlations were determined between MRE analysis methods and fibrosis stage. Thresholds for classifying the presence of fibrosis and of advanced fibrosis were computed and cross-validated. In 90 children with a mean age of 13.1 ± 2.4 years, median hepatic stiffness was 2.35 kPa. Stiffness values derived by each reading center were strongly correlated with each other (r = 0.83). All three analyses were significantly correlated with fibrosis stage (center 1, ρ = 0.53; center 2, ρ = 0.55; and automated analysis, ρ = 0.52; P

Hepatocellular carcinoma can be diagnosed on a needle biopsy of the liver; however, uncertainty may arise because of the inherent complexity of liver histology. This article aims to provide practicing pathologists with tools for the approach to mass-directed liver biopsies clinically concerning for hepatocellular carcinoma. The examination of routine hematoxylin-eosin stains and the use of ancillary histochemical and immunohistochemical stains are discussed. Sections reviewing liver carcinoma with biphenotypic differentiation and the challenge of dysplastic nodules are included.

OBJECTIVE Approximately 18 million people in the U.S. have coexisting type 2 diabetes and nonalcoholic fatty liver disease (NAFLD). It is not known who among these patients has nonalcoholic steatohepatitis (NASH) with advanced fibrosis. Therefore, we aimed to determine factors that are associated with both NASH and advanced fibrosis in patients with diabetes and NAFLD in order to identify who should be prioritized for referral to a hepatologist for further diagnostic evaluation and treatment. RESEARCH DESIGN AND METHODS This study was derived from the NASH Clinical Research Network studies and included 1,249 patients with biopsy-proven NAFLD (including a model development cohort of 346 patients and an independent validation cohort of 100 patients with type 2 diabetes as defined by the American Diabetes Association criteria). Outcome measures were presence of NASH or advanced fibrosis (stage 3 or 4) using cross-validated, by jackknife method, multivariable-adjusted area under the receiver operating characteristic curve (AUROC) and 95% CI. RESULTS The mean ± SD age and BMI of patients with diabetes and NAFLD was 52.5 ± 10.3 years and 35.8 ± 6.8 kg/m2, respectively. The prevalence of NASH and advanced fibrosis was 69.2% and 41.0%, respectively. The model for NASH included white race, BMI, waist, alanine aminotransferase (ALT), Aspartate aminotransferase (AST), albumin, HbA1c, HOMA of insulin resistance, and ferritin with an AUROC of 0.80 (95% CI 0.75–0.84, P = 0.007). The specificity, sensitivity, negative predictive values (NPVs), and positive predictive values (PPVs) were 90.0%, 56.8%, 47.7%, and 93.2%, respectively, and the model correctly classified 67% of patients as having NASH. The model for predicting advanced fibrosis included age, Hispanic ethnicity, BMI, waist-to-hip ratio, hypertension, ALT-to-AST ratio, alkaline phosphatase, isolated abnormal alkaline phosphatase, bilirubin (total and direct), globulin, albumin, serum insulin, hematocrit, international normalized ratio, and platelet count with an AUROC of 0.80 (95% CI 0.76–0.85, P < 0.001). The specificity, sensitivity, NPV, and PPV were 90.0%, 57%, 75.1%, and 80.2%, respectively, and the model correctly classified 76.6% of patients as having advanced fibrosis. Results remained consistent for both models in the validation cohort. The proposed model performed better than the NAFLD fibrosis score in detecting advanced fibrosis. CONCLUSIONS Routinely available clinical variables can be used to quantify the likelihood of NASH or advanced fibrosis in adult diabetic patients with NAFLD. The clinical models presented can be used to guide clinical decision making about referrals of patients with diabetes and NAFLD to hepatologists.

Gallbladder polyps are seen on as many as 7% of gallbladder ultrasonographic images. The differential diagnosis for a polypoid gallbladder mass is wide and includes pseudotumors, as well as benign and malignant tumors. Tumefactive sludge may be mistaken for a gallbladder polyp. Pseudotumors include cholesterol polyps, adenomyomatosis, and inflammatory polyps, and they occur in that order of frequency. The most common benign and malignant tumors are adenomas and primary adenocarcinoma, respectively. Polyp size, shape, and other ancillary imaging findings, such as a wide base, wall thickening, and coexistent gallstones, are pertinent items to report when gallbladder polyps are discovered. These findings, as well as patient age and risk factors for gallbladder cancer, guide clinical decision making. Symptomatic polyps without other cause for symptoms, an age over 50 years, and the presence of gallstones are generally considered indications for cholecystectomy. Incidentally noted pedunculated polyps smaller than 5 mm generally do not require follow-up. Polyps that are 6-10 mm require follow-up, although neither the frequency nor the length of follow-up has been established. Polyps that are larger than 10 mm are typically excised, although lower size thresholds for cholecystectomy may be considered for patients with increased risk for gallbladder carcinoma, such as patients with primary sclerosing cholangitis.