Liver transplantation in the treatment of severe iatrogenic liver injuries

The place of liver transplantation in the treatment of severe iatrogenic liver injuries has not yet been widely discussed in the literature. Bile duct injuries during cholecystectomy represent the leading cause of liver transplantation in this setting, while other indications after abdominal surgery are less common. Urgent liver transplantation for the treatment of severe iatrogenic liver injury may-represent a surgical challenge requiring technically difficult and time consuming procedures. A debate is ongoing on the need for centralization of complex surgery in tertiary referral centers. The early referral of patients with severe iatrogenic liver injuries to a tertiary center with experienced hepato-pancreatobiliary and transplant surgery has emerged as the best treatment of care. Despite widespread interest in the use of liver transplantation as a treatment option for severe iatrogenic injuries, reported experiences indicate few liver transplants are performed. This review analyzes the literature on liver transplantation after hepatic injury and discusses our own experience along with surgical advances and future prospects in this uncommon transplant setting.

COVID-19 related liver injuries in pregnancy

While severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)quickly spread across the globe,our understanding of its pathogenic mechanisms evolved.Importantly,coronavirus disease 2019(COVID-19)is now considered a syndromic multisystem inflammatory disease involving not only the respiratory system but also the cardiovascular,excretory,nervous,musculoskeletal,and gastrointestinal systems.Moreover,a membrane-bound form of angiotensin-converting enzyme 2,the entry receptor for SARS-CoV-2,is expressed on the surface of cholangiocytes and hepatocytes,suggesting the potential of COVID-19 to involve the liver.With the widespread distribution of SARS-CoV-2 throughout the population,infection during pregnancy is no longer a rare occurrence;however,little is known about the course of hepatic injuries and related outcomes in pregnant SARS-CoV-2-positive women.Thus,the understudied topic of COVID-related liver disease during pregnancy poses a great challenge for the consulting gynecologist and hepatologist.In this review,we aim to describe and summarize potential liver injuries in pregnant women with COVID-19.

Elafibranor:A promising treatment for alcoholic liver disease,metabolic-associated fatty liver disease,and cholestatic liver disease

Liver diseases pose a significant threat to human health.Although effective therapeutic agents exist for some liver diseases,there remains a critical need for advancements in research to address the gaps in treatment options and improve patient outcomes.This article reviews the assessment of Elafibranor's effects on liver fibrosis and intestinal barrier function in a mouse model of alcoholic liver disease(ALD),as reported by Koizumi et al in the World Journal of Gastroenterology.We summarize the impact and mechanisms of Elafibranor on ALD,metabolic-associated fatty liver disease,and cholestatic liver disease based on current research.We also explore its potential as a dual agonist of PPARα/δ,which is undergoing Phase III clinical trials for metabolic-associated steatohepatitis.Our goal is to stimulate further investigation into Elafibranor's use for preventing and treating these liver diseases and to provide insights for its clinical application.

Effects of basic fibroblast growth factor on ischemic gut and liver injuries

AIMS To explore the possible effects of basic fibrob- last growth factor (bFGF) on ischemic gut and liver in- juries after trauma. METHODS Animal model of super mesenteric artery (SMA) occlusion was used in this study. Seventy-two Wistar rats were divided into three groups of 24 rats each. Each animal in group 1 (bFGF treated) was in- jected with 4 μg of bFGF in 0.15 ml of normal saline solution containing 0.1%(w/v) heparin through the jugular vein at the onset of reperfusion. Animals in group 2 (saline treated) received the same vehicle, but without bFGF. Group 3 (sham-operated) ani- mals were treated with the same operations,but without SMA occlusion. Liver function parameters, serum TNFα,bacterial examination and pathological study were used to evaluate the results. RESULTS In group 1,the amounts of ALT and AST and serum TNFα were reduced significantly at 6,24 and 48 hours as compared with group 2. Bacterial ex- amination showed that the bacterial translocation from gut to liver,spleen and MLN in group 1 was much lower than that in group 2. The pathological results support the concept of significant protecting effects of bFGF. CONCLUSIONS Venous administration of bFGF may help reduce gut and liver injuries after ischemia and reperfusion. Its mechanism of action may involve the mitogenic and non-mitogenic effects of bFGF.

Screening for metabolic dysfunction-associated fatty liver disease:Time to discard the emperor’s clothes of normal liver enzymes?

Metabolic dysfunction-associated fatty liver disease(MAFLD)is the most prevalent chronic liver condition worldwide.Current liver enzyme-based screening methods have limitations that may missed diagnoses and treatment delays.Regarding Chen et al,the risk of developing MAFLD remains elevated even when alanine aminotransferase levels fall within the normal range.Therefore,there is an urgent need for advanced diagnostic techniques and updated algorithms to enhance the accuracy of MAFLD diagnosis and enable early intervention.This paper proposes two potential screening methods for identifying individuals who may be at risk of developing MAFLD:Lowering these thresholds and promoting the use of noninvasive liver fibrosis scores.

Effect of Avocado （Persea Americana）, Cabbage （Brassica Oleracea） and Ginger （Zingiber Officinale） on Rat Liver and Thyroid Injuries Induced by CCI4 （Carbon Tetrachloride）

Avocado, Cabbage, and Ginger are a part of a regular human diet and have antioxidant, and antitumor effects. The effect of AVOE （avocado）, GE （Ginger） and CE （Cabbage） extracts separately on liver NO （nitric oxide）, MDA （malondialdehyde）, as well as serum AST （aspartate aminotransferase）, ALT （alanine aminotransferase）, total bilirubin, TC （total cholesterol）, T.G （triglyceride）, HDL cholesterol （high-density lipoprotein）, LDL cholesterol （low-density lipoprotein）, TSH （thyroid-stimulating hormone）, T3 （Triiodothyronine）, T4 （Thyroxine） in rats treated and untreated with CC14 （carbon tetrachloride） was studied. The levels of NO, MDA, as well as serum AST, ALT, total bilirubin, TC, T.G, LDL, and TSH, showed an elevation while, HDL, T3 and T4 showed the decline in rats treated with CC14 as compared to control. Treatment of rats with AVOE and GE pre, during, and post CC14 administration improve NO, MDA, as well as serum AST, ALT, total bilirubin, TC, T.G, HDL, LDL, TSH, T3, T4 as compared to CC14. Treatment of rats with CE pre, during, and post CC14 administration did not improve in the thyroid hormones and lipid profile levels as compared to CC14. These findings suggest that avocado and ginger treatment exerts a protective effect on metabolic disorders by decreasing oxidative stress.

Predicting liver function after hemihepatectomy in patients with hepatocellular carcinoma using different modalities

In response to Dr.Yue et al's study on prognostic factors for post-hemihep-atectomy outcomes in hepatocellular carcinoma(HCC)patients,this critical review identifies methodological limitations and proposes enhancements for future research.While the study identifies liver stiffness measure and standard residual liver volume as potential predictors,concerns regarding small sample size,reliance on biochemical markers for safety assessment,and inadequate ad-justment for confounding variables are raised.Recommendations for rigorous methodology,including robust statistical analysis,consideration of confounding factors,and selection of outcome measures with clinical components,are proposed to strengthen prognostic assessments.Furthermore,validation of novel evaluation models is crucial for enhancing clinical applicability and advancing understanding of postoperative outcomes in patients with HCC undergoing hem-ihepatectomy.

Pediatric and adult liver transplantation in Bahrain: The experiences in a country with no available liver transplant facilities

BACKGROUND Liver transplantation(LT)is a life-saving procedure for patients with end-stage liver disease and has become the standard and most effective treatment method for these patients.There are many indications for LT that vary between countries and settings.The outcome of LT depends on the available facilities and surgical expertise,as well as the types of liver graft donors available.AIM To assess the clinical characteristics of patients from Bahrain who underwent LT overseas,and analyze factors affecting their survival.METHODS In this retrospective cohort study,we reviewed the medical records and overseas committee registry information of all pediatric and adult patients who were sent overseas to undergo LT by the Pediatric and Medical Departments of Salmaniya Medical Complex and Bahrain Defence Force Hospital via the Overseas Treatment Office,Ministry of Health,Kingdom of Bahrain,between 1997 and 2023.Demographic data,LT indication,donor-recipient relationship,overseas LT center,graft type,post-LT medications,and LT complications,were collected.Outcomes measured included the overall and 5-year LT survival rate.Fisher’s exact,Pearsonχ2,and Mann-Whitney U tests were used to compare the pediatric and the adults’group in terms of clinical characteristics,donor-recipient relationship,medication,complications,and outcome.Survival analysis was estimated via the Kaplan-Meier’s method.Univariate and multivariate analyses were used to detect predictors of survival.RESULTS Of the 208 eligible patients,170(81.7%)were sent overseas to undergo LT while 38(18.3%)remained on the waiting list.Of the 170 patients,167(80.3%)underwent LT and were included in the study.The majority of the patients were Bahraini(91.0%),and most were males(57.5%).One-hundred-and-twenty(71.8%)were adults and 47(28.3%)were children.The median age at transplant was 50.0[interquartile range(IQR):14.9–58.4]years.The main indication for pediatric LT was biliary atresia(31.9%),while that of adult LT was hepatitis C-related cirrhosis(35.0%).Six(3.6%)patients required re-transplantation.Most patients received a living-related liver graft(82%).Pediatric patients received more living and related grafts than adults(P=0.038 and P=0.041,respectively),while adult patients received more cadaveric and unrelated grafts.Most patients required long-term immunosuppressive therapy after LT(94.7%),of which tacrolimus was the most prescribed(84.0%),followed by prednisolone(50.7%),which was prescribed more frequently for pediatric patients(P=0.001).Most patients developed complications(62.4%)with infectious episodes being the most common(38.9%),followed by biliary stricture(19.5%).Tonsilitis and sepsis(n=12,8.1%for each)were the most frequent infections.Pediatric patients experienced higher rates of infection,rejection,and early poor graft function than adult patients(P<0.001,P=0.003,and P=0.025,respectively).The median follow-up time was 6.5(IQR:2.6–10.6)years.The overall survival rate was 84.4%,the 5-year survival rate,86.2%,and the mortality rate,15.6%.Younger patients had significantly better odds of survival(P=0.019)and patients who survived had significantly longer follow-up periods(P<0.001).CONCLUSION Patients with end-stage liver disease in Bahrain shared characteristics with those from other countries.Since LT facilities are not available,an overseas LT has offered them great hope.

Endoscopic ultrasound-guided tissue acquisition for the diagnosis of focal liver lesion

In patients with liver tumors,the histopathology examination can assist in diagnosis,staging,prognosis,and therapeutic management strategy.Endoscopic ultrasound(EUS)-guided tissue acquisition using fine needle aspiration(FNA)or more newly fine needle biopsy(FNB)is a well-developed technique in order to evaluate and differentiate the liver masses.The goal of the EUS-FNA or EUS-FNB is to provide an accurate sample for a histopathology examination.Therefore,malignant tumors such as hepatocarcinoma,cholangiocarcinoma and liver metastasis or benign tumors such as liver adenoma,focal hyperplastic nodular tumors and cystic lesions can be accurately diagnosed using EUS-guided tissue acquisition.EUS-FNB using 19 or 22 Ga needle provide longer samples and a higher diagnostic accuracy in patients with liver masses when compared with EUS-FNA.Few data are available on the diagnostic accuracy of EUS-FNB when compared with percutaneously,ultrasound,computer tomography or transjugulary-guided liver biopsies.This review will discuss the EUS-guided tissue acquisition options in patients with liver tumors and its efficacy and safety in providing accurate samples.The results of the last studies comparing EUS-guided liver biopsy with other conventional techniques are presented.The EUS-guided tissue acquisition using FNB can be a suitable technique in suspected liver lesions in order to provide an accurate histopathology diagnosis,especially for those who require endoscopy.

Major liver resections,perioperative issues and posthepatectomy liver failure:A comprehensive update for the anesthesiologist

Significant advances in surgical techniques and relevant medium-and long-term outcomes over the past two decades have led to a substantial expansion in the indications for major liver resections.To support these outstanding results and to reduce perioperative complications,anesthesiologists must address and master key perioperative issues(preoperative assessment,proactive intraoperative anesthesia strategies,and implementation of the Enhanced Recovery After Surgery approach).Intensive care unit monitoring immediately following liver surgery remains a subject of active and often unresolved debate.Among postoperative complications,posthepatectomy liver failure(PHLF)occurs in different grades of severity(A-C)and frequency(9%-30%),and it is the main cause of 90-d postoperative mortality.PHLF,recently redefined with pragmatic clinical criteria and perioperative scores,can be predicted,prevented,or anticipated.This review highlights:(1)The systemic consequences of surgical manipulations anesthesiologistsmust respond to or prevent,to positively impact PHLF(a proactive approach);and(2)the maximal intensivetreatment of PHLF,including artificial options,mainly based,so far,on Acute Liver Failure treatment(s),to buytime waiting for the recovery of the native liver or,when appropriate and in very selected cases,toward livertransplant.Such a clinical context requires a strong commitment to surgeons,anesthesiologists,and intensivists towork together,for a fruitful collaboration in a mandatory clinical continuum.

Anti-lipid peroxidation and protection of liver mitochondria against injuries by picroside Ⅱ

AIM: To investigate the anti-lipid peroxidation and protection of liver mitochondria against injuries in mice with liver damage by picroside Ⅱ. METHODS: Three animal models of liver damage induced by carbon tetrachloride (CCl4: 0.1 mL/10 g, ip), D-galactasamine (D-GaIN: 500 mg/kg, ip) and acetaminophen (AP: 0.15 g/kg, ip) were respectively treated with various concentrations of picroside Ⅱ (5, 10, 20 mg/kg, ig). Then we chose the continuously monitoring method (recommended by International Clinical Chemistry League) to analyze serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) values, Marland method to detect the activity of manganese-superoxide dismutase (SOD) in liver mitochondria, TBA colorimetry to determine the content of malonicdialdehyde (MDA) in liver tissue, DTNB method to evaluate the activity of glutathioneperoxidase (GSH-Px) and Lowry method to detect protein level in liver tissue. Meanwhile, effects of picroside Ⅱ on the activity of ATPase and swelling extent of mitochondria in hepatocytes damaged by AP were also evaluated. RESULTS: Picroside Ⅱ could significantly prevent liver toxicity in the three models of liver damage. It decreased the high levels of ALT and AST in serum induced by the administration of CCl4, D-GaIN and AP, reduced the cellular damage of liver markedly, and appeared to be even more potent than the positive control drug of biphenyl dimethyl dicarboxylate pilules (DDB). In groups treated with different doses of picroside Ⅱ, compared to the model group, the content of MDA in serum decreased evidently, whereas the content of SOD and GSH-Px increased in a dose dependent manner, and the difference was statistically significant. Further, in the study of AP model, picroside Ⅱ inhibited AP-induced liver toxicity in mice, enhanced the activity of ATPase, improved the swelling extent of mitochondria and helped to maintain a normal balance of energy metabolism. CONCLUSION: Picroside II can evidently relieve hepatocyte injuries induced by CCI4, D-GaIN and AP, help scavenge free radicals, protect normal constructions of mitochondria membrane and enhance the activity of ATPase in mitochondria, thereby modulating the balance of liver energy metabolism, which might be part of the mechanisms of hepatoprotective effects of picroside Ⅱ.

Role of albumin-bilirubin score in non-malignant liver disease

The albumin-bilirubin(ALBI)score,which was proposed to assess the prognosis of patients with hepatocellular carcinoma,has gradually been extended to other liver diseases in recent years,including primary biliary cholangitis,liver cirrhosis,hepatitis,liver transplantation,and liver injury.The ALBI score is often compared with classical scores such as the Child-Pugh and model for end-stage liver disease scores or other noninvasive prediction models.It is widely employed because of its immunity to subjective evaluation indicators and ease of obtaining detection indicators.An increasing number of studies have confirmed that it is highly accurate for assessing the prognosis of patients with chronic liver disease;additionally,it has demonstrated good predictive performance for outcomes beyond survival in patients with liver diseases,such as decompensation events.This article presents a review of the application of ALBI scores in various non-malignant liver diseases.

Ex vivo liver resection and auto-transplantation as an alternative for the treatment of liver malignancies: Progress and challenges

Hepatectomy is still the major curative treatment for patients with liver malignancies.However,it is still a big challenge to remove the tumors in the central posterior area,especially if their location involves the retrohepatic inferior vena cava and hepatic veins.Ex vivo liver resection and auto-transplantation(ELRA),a hybrid technique of the traditional liver resection and transplantation,has brought new hope to these patients and therefore becomes a valid alternative to liver transplantation.Due to its technical difficulty,ELRA is still concentrated in a few hepatobiliary centers that have experienced surgeons in both liver resection and liver transplantation.The efficacy and safety of this technique has already been demonstrated in the treatment of benign liver diseases,especially in the advanced alveolar echinococcosis.Recently,the application of ELRA for liver malignances has gained more attention.However,standardization of clinical practice norms and international consensus are still lacking.The prognostic impact in these oncologic patients also needs further evaluation.In this review,we summarized the principles and recent progresses on ELRA.

Liver transplantation as an alternative for the treatment of non-resectable liver colorectal cancer: Advancing the therapeutic algorithm

Colorectal cancer is a leading cause of cancerrelated mortality,with nearly half of the affected patients developing liver metastases.For three decades,liver resection(LR)has been the primary curative strategy,yet its applicability is limited to about 20%of cases.Liver transplantation(LT)for unresectable metastases was attempted unsuccessfully in the 1990s,with high rates of perioperative death and recurrence.There is now more interest in this strategy due to improvements in systemic therapies and surgical techniques.A significant study conducted by the Oslo group showed that patients receiving liver transplants had a 60%chance of survival after five years.Significantly better results have been achieved by using advanced imaging for risk stratification and further refining selection criteria,especially in the Norvegian SECA trials.This review carefully charts the development and history of LT as a treatment option for colorectal cancer liver metastases.The revolutionary path from the early days of exploratory surgery to the current situation of cautious optimism is traced,highlighting the critical clinical developments and improved patient selection standards that have made LT a potentially curative treatment for such challenging very well selected cases.

Liver transplantation as an alternative for the treatment of neuroendocrine liver metastasis: Appraisal of the current evidence

Background:Liver transplantation(LT)for neuroendocrine liver metastases(NELM)is still in debate.Studies comparing LT with liver resection(LR)for NELM are scarce,as patient selection is heterogeneous and experience is limited.The goal of this review was to provide a critical analysis of the evidence on LT versus LR in the treatment of NELM.Data sources:A scoping literature search on LT and LR for NELM was performed with PubMed,including English articles up to March 2023.Results:International guidelines recommend LR for NELM in resectable,well-differentiated tumors in the absence of extrahepatic metastatic disease with superior results of LR compared to systemic or liver-directed therapies.Advanced liver surgery has extended resectability criteria whilst entailing increased perioperative risk and short disease-free survival.In highly selected patients(based on the Milan criteria)with unresectable NELM,oncologic results of LT are promising.Prognostic factors include tumor biology(G1/G2)and burden,waiting time for LT,patient age and extrahepatic spread.Based on low-level evi-dence,LT for low-grade NELM within the Milan criteria resulted in improved disease-free survival and overall survival compared to LR.The benefits of LT were lost in patients beyond the Milan NELM-criteria.Conclusions:With adherence to strict selection criteria especially tumor biology,LT for NELM is becoming a valuable option providing oncologic benefits compared to LR.Recent evidence suggests even stricter selection criteria with regard to tumor biology.

Histopathological impact of SARS-CoV-2 on the liver:Cellular damage and long-term complications

Coronavirus disease 2019(COVID-19),caused by the highly pathogenic severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),primarily impacts the respiratory tract and can lead to severe outcomes such as acute respiratory distress syndrome,multiple organ failure,and death.Despite extensive studies on the pathogenicity of SARS-CoV-2,its impact on the hepatobiliary system remains unclear.While liver injury is commonly indicated by reduced albumin and elevated bilirubin and transaminase levels,the exact source of this damage is not fully understood.Proposed mechanisms for injury include direct cytotoxicity,collateral damage from inflammation,drug-induced liver injury,and ischemia/hypoxia.However,evidence often relies on blood tests with liver enzyme abnormalities.In this comprehensive review,we focused solely on the different histopathological manifestations of liver injury in COVID-19 patients,drawing from liver biopsies,complete autopsies,and in vitro liver analyses.We present evidence of the direct impact of SARS-CoV-2 on the liver,substantiated by in vitro observations of viral entry mechanisms and the actual presence of viral particles in liver samples resulting in a variety of cellular changes,including mitochondrial swelling,endoplasmic reticulum dilatation,and hepatocyte apoptosis.Additional ly,we describe the diverse liver pathology observed during COVID-19 infection,encompassing necrosis,steatosis,cholestasis,and lobular inflammation.We also discuss the emergence of long-term complications,notably COVID-19-related secondary sclerosing cholangitis.Recognizing the histopathological liver changes occurring during COVID-19 infection is pivotal for improving patient recovery and guiding decision-making.

Alanine aminotransferase predicts incident steatotic liver disease of metabolic etiology: Long life to the old biomarker!

Alanine aminotransferase(ALT)serum levels increase because of hepatocellular damage.Metabolic dysfunction-associated fatty liver disease(MAFLD),which identifies steatotic liver disease(SLD)associated with≥2 metabolic abnormalities,has prominent sexual differences.The Metabolic Syndrome defines a cluster comprising abdominal obesity,altered glucose metabolism,dyslipidemia,and hypertension.Male sex,body mass index,glucose,lipids,ferritin,hypertension,and age independently predict ALT levels among blood donors.Over the last few decades,the reference range of ALT levels has been animatedly debated owing to attempts to update sex-specific reference ranges.With this backset,Chen et al have recently published a study which has two main findings.First,>80%of indi-viduals with MAFLD had normal ALT levels.Second,there was a linear increa-sing trend in the association between cumulative excess high-normal ALT levels and the rate of incident MAFLD.This study has biologically credible findings.However,it inaccurately considered sex differences in the MAFLD arena.Therefore,future studies on SLD owing to metabolic dysfunction should adopt locally determined and prospectively validated reference ranges of ALT and carefully consider sex differences in liver enzymes and MAFLD pathobiology.

Metabolic dysfunction-associated steatotic liver disease:Navigating terminological evolution,diagnostic frontiers and therapeutic horizon-an editorial exploration

Metabolic dysfunction-associated steatotic liver disease(MASLD),once known as non-alcoholic fatty liver disease(NAFLD),represents a spectrum of liver disorders characterized by lipid accumulation within hepatocytes.The redefinition of NAFLD in 2023 marked a significant reposition in terminology,emphasizing a broader understanding of liver steatosis and its associated risks.MASLD is now recognized as a major risk factor for liver cirrhosis,hepatocellular carcinoma,and systemic complications such as cardiovascular diseases or systemic inflammation.Diagnostic challenges arise,particularly in identifying MASLD in lean individuals,necessitating updated diagnostic protocols and investing in non-invasive diagnostic tools.Therapeutically,there is an urgent need for effective treatments targeting MASLD,with emerging pharmacological options focusing on,among others,carbohydrate and lipid metabolism.Additionally,understanding the roles of bile acid metabolism,the microbiome,and dietary interventions in MASLD pathogenesis and management holds promise for innovative therapeutic approaches.There is a strong need to emphasize the importance of collaborative efforts in understanding,diagnosing,and managing MASLD to improve physicians’approaches and patient outcomes.

Impact of microplastics and nanoplastics on liver health:Current understanding and future research directions

With continuous population and economic growth in the 21st century,plastic pollution is a major global issue.However,the health concern of microplastics/nanoplastics(MPs/NPs)decomposed from plastic wastes has drawn public attention only in the recent decade.This article summarizes recent works dedicated to understanding the impact of MPs/NPs on the liver-the largest digestive organ,which is one of the primary routes that MPs/NPs enter human bodies.The interrelated mechanisms including oxidative stress,hepatocyte energy re-distribution,cell death and autophagy,as well as immune responses and inflammation,were also featured.In addition,the disturbance of microbiome and gut-liver axis,and the association with clinical diseases such as metabolic dysfunction-associated fatty liver disease,steatohepatitis,liver fibrosis,and cirrhosis were briefly discussed.Finally,we discussed potential directions in regard to this trending topic,highlighted current challenges in research,and proposed possible solutions.

Update in lean metabolic dysfunction-associated steatotic liver disease

BACKGROUND A new nomenclature consensus has emerged for liver diseases that were previously known as non-alcoholic fatty liver disease(NAFLD)and metabolic dysfunction-associated fatty liver disease(MAFLD).They are now defined as metabolic dysfunction-associated steatotic liver disease(MASLD),which includes cardiometabolic criteria in adults.This condition,extensively studied in obese or overweight patients,constitutes around 30%of the population,with a steady increase worldwide.Lean patients account for approximately 10%-15%of the MASLD population.However,the pathogenesis is complex and is not well understood.AIM To systematically review the literature on the diagnosis,pathogenesis,characteristics,and prognosis in lean MASLD patients and provide an interpretation of these new criteria.METHODS We conducted a comprehensive database search on PubMed and Google Scholar between January 2012 and September 2023,specifically focusing on lean NAFLD,MAFLD,or MASLD patients.We include original articles with patients aged 18 years or older,with a lean body mass index categorized according to the World Health Organization criteria,using a cutoff of 25 kg/m2 for the general population and 23 kg/m2 for the Asian population.RESULTS We include 85 studies in our analysis.Our findings revealed that,for lean NAFLD patients,the prevalence rate varied widely,ranging from 3.8%to 34.1%.The precise pathogenesis mechanism remained elusive,with associations found in genetic variants,epigenetic modifications,and adaptative metabolic response.Common risk factors included metabolic syndrome,hypertension,and type 2 diabetes mellitus,but their prevalence varied based on the comparison group involving lean patients.Regarding non-invasive tools,Fibrosis-4 index outperformed the NAFLD fibrosis score in lean patients.Lifestyle modifications aided in reducing hepatic steatosis and improving cardiometabolic profiles,with some medications showing efficacy to a lesser extent.However,lean NAFLD patients exhibited a worse prognosis compared to the obese or overweight counterpart.CONCLUSION MASLD is a complex disease comprising epigenetic,genetic,and metabolic factors in its pathogenesis.Results vary across populations,gender,and age.Limited data exists on clinical practice guidelines for lean patients.Future studies employing this new nomenclature can contribute to standardizing and generalizing results among lean patients with steatotic liver disease.