Kleiner, David Erwin

Noncirrhotic portal hypertension has historically been described using heterogeneous and region-specific terminology—such as idiopathic portal hypertension (IPH), noncirrhotic portal fibrosis (NCPF), obliterative portal venopathy, and nodular regenerative hyperplasia—leading to substantial variability in diagnosis, reporting, and international research collaboration. Differences in guideline definitions from major societies (AASLD, EASL, and APASL), together with the presence of characteristic histologic lesions in patients without clinically overt portal hypertension, have further complicated disease classification. To address these challenges, a large, multisociety, international initiative was convened to harmonize nomenclature and diagnostic criteria. Representatives from liver, pathology, and pediatric hepatology societies across the Americas, Europe, and Asia participated in a structured consensus process that included specialized working groups and external Delphi validation. The initiative produced a globally harmonized and implementable diagnostic framework. Consensus was reached that the terms porto-sinusoidal vascular disorder (PSVD) and NCPF may be used interchangeably when identical diagnostic criteria are applied, and that they should be written as PSVD or NCPF . The diagnosis was defined as fundamentally clinicopathological, requiring integrated assessment. Core principles include the need for a high-quality liver biopsy (≥10 mm), mandatory exclusion of cirrhosis, and systematic exclusion of specific alternative conditions. Importantly, the consensus recognizes that PSVD or NCPF may be diagnosed even without clinical portal hypertension and may coexist with other liver diseases, provided cirrhosis is excluded. Standardized major and minor histologic criteria were developed collaboratively by expert pathologists and externally validated. Features of portal hypertension were harmonized into specific and nonspecific categories applicable to routine clinical practice. An integrated diagnostic scoring system incorporating histology, clinical features, associated conditions, and concommitant etiologies was developed and validated using the Delphi method. This consensus provides the first internationally endorsed, unified framework for the diagnosis of PSVD or NCPF. Its global implementation is expected to reduce diagnostic variability, improve comparability across regions, and facilitate the development of robust, internationally harmonized clinical and translational research cohorts.

Listing and transplanting patients with acute liver failure (ALF) is challenging, requiring rapid assessment of the likelihood of recovery. The availability of a large number of ALF liver explants, along with their clinical data, afforded an opportunity to retrospectively evaluate liver transplantation (LT) decision-making. We hypothesized that, with the benefit of hindsight, a small number of patients might have recovered without LT. Three hundred liver explants from ALF patients of varying etiologies who had undergone LT over 22 years in the Acute Liver Failure Study Group registry were reviewed for histopathological features and degree of necrosis by a committee of 8 hepatopathologists. A second committee of 8 experienced transplant hepatologists independently reviewed clinical data on these same 300 patients and retrospectively scored the likelihood that each patient required transplantation. Only 3 (1%) of those reviewed by the Clinical Committee were considered to “Definitely” not require liver grafting, while an additional 10 (3.3%) were deemed to “Possibly” not require transplantation (Not Likely Group, N=13). There was no difference in the degree of necrosis in explants in these groups, when compared to the remaining Likely Group, N=287 (95.6%), except in acetaminophen (APAP)-associated ALF, where the degree of necrosis was more uniformly graded as severe, correlating with the need for transplantation. Virtually every patient undergoing LT for ALF retrospectively appeared to need their transplant, based on expert clinical consensus review. Overall, there was poor correlation between clinical severity and apparent degree of necrosis seen in the 300 liver explants, except perhaps for APAP subjects.

Liver biopsies have consistently contributed to our understanding of the pathogenesis and aetiologies of acute liver disease. As other diagnostic modalities have been developed and refined, the role of biopsy in the management of patients with acute liver failure (ALF), acute‐on‐chronic liver failure (ACLF) and acute hepatitis, including acute liver injury (ALI), has changed. Liver biopsy remains particularly valuable when first‐line diagnostic algorithms fail to determine aetiology. Despite not being identified as a mandatory diagnostic tool in recent clinical guidelines for the management of ALF or ACLF, many centres continue to undertake biopsies given the relative safety of transjugular biopsy in this setting. Several studies have demonstrated that liver biopsy can provide prognostic information, particularly in the context of so‐called indeterminate hepatitis, and is extremely useful in excluding conditions such as metastatic tumours that would preclude transplantation. In addition, its widespread use of percutaneous biopsies in cases of less severe acute liver injury, for example in the establishment of a diagnosis of acute presentation of autoimmune hepatitis or confirmation of a probable or definite drug‐induced liver injury (DILI), has meant that many centres have seen a shift in the ratio of specimens they are receiving from patients with chronic to acute liver disease. Histopathologists therefore need to be equipped to deal with these challenging specimens. This overview provides an insight into the contemporary role of biopsies (as well as explant and autopsy material) in diagnosing acute liver disease. It outlines up‐to‐date clinical definitions of liver injury and considers recent recommendations for the diagnosis of AIH and drug‐induced, autoimmune‐like hepatitis (DI‐AIH).

ImportanceDisparities in treatment initiation may affect outcomes, but data on racially diverse populations with chronic hepatitis B virus (HBV) infection are limited.ObjectiveTo examine whether HBV treatment initiation and outcomes differ among racial groups.Design, Setting, and ParticipantsFrom January 14, 2011, to January 28, 2018, hepatitis B surface antigen—positive adults (age ≥18 years) not receiving anti-HBV therapy were enrolled and followed up at weeks 12, 24, and every 24 weeks thereafter in a multicenter longitudinal cohort study (Hepatitis B Research Network [HBRN] adult cohort study) conducted in North America. The last study visit and data collection were completed January 28, 2019. Data were analyzed from August 27, 2021, to August 25, 2022. All HBRN participants were included unless they had acute HBV, HIV, hepatitis C or D, less than 24-weeks of follow-up after enrollment, initiated treatment at or immediately after enrollment, or had unknown race.ExposuresParticipants had clinical and laboratory assessments and could receive anti-HBV treatment after enrollment.Main Outcomes and MeasuresHepatitis B virus treatment initiation and major adverse liver outcomes (hepatic decompensation, hepatocellular carcinoma, liver transplant, and death).ResultsOf 1550 participants, 193 (12%) were African American or Black, 1157 (75%) were Asian, 157 (10%) were White, and 43 (3%) were other races; 789 (51%) were women, and the median age was 41.2 (IQR, 32.9-51.6) years. Sociodemographic and virologic parameters differed between groups. During 5727 person-years of follow-up, 504 participants initiated treatment, with incidences of 4.8 per 100 person-years in African American or Black individuals, 9.9 per 100 person-years in Asian individuals, 6.6 per 100 person-years in White individuals, and 7.9 per 100 person-years in those of other races (P < .001). A lower proportion (14%) of African American or Black participants met treatment criteria compared with Asian (22%) and White (27%) individuals (P = .01). The cumulative probabilities of treatment initiation after meeting the criteria were not significantly different among racial groups (African American or Black, 0.45; Asian, 0.38; White, 0.40 at 48 weeks and African American or Black, 0.45; Asian, 0.51; White, 0.51 at 72 weeks; P = .68). The incidence of major adverse liver outcomes was 0.1 per 100 person-years and did not differ by race.Conclusions and RelevanceIn this observational study of chronic HBV, African American or Black participants were less likely than individuals of other races to meet treatment criteria, but among those who did, HBV treatment receipt did not differ significantly by race or socioeconomic factors. Not all eligible participants initiated treatment, but adverse liver outcomes were rare. These findings may not be generalizable to patients with chronic HBV receiving care in other settings.

Abstract Background and Aims The NASH Clinical Research Network histologic scoring system, the gold‐standard NASH histology assessment for clinical trials, has demonstrated intrarater and interrater variability. An expert panel in a previous systematic Research and Development/University of California Los Angeles (RAND/UCLA) study determined that existing histologic scoring systems do not fully capture NASH disease activity and fibrosis, and standardized definitions of histologic features are needed. We evaluated the reliability of existing and alternate histologic measures and their correlations with a disease activity visual analog scale to propose optimal components for an expanded NAFLD activity score (NAS). Approach and Results Four liver pathologists who were involved in the prior RAND/UCLA study underwent standardized training and multiple discussions with the goal of improving agreement. They were blinded to clinical information and scored histologic measures twice, ≥2 weeks apart, for 40 liver biopsies representing the full spectrum of NAFLD. Index intraclass correlation coefficient (ICC) estimates demonstrated intrarater (0.80–0.85) and interrater (0.60–0.72) reliability. Hepatocyte ballooning items had similar interrater ICCs (0.68–0.79), including those extending scores from 0–2 to 0–4. Steatosis measures (interrater ICCs, 0.72–0.80) correlated poorly with disease activity. Correlations with disease activity were largest for hepatocyte ballooning and Mallory‐Denk bodies (MDBs), with both used to develop the expanded NAS (intrarater ICC, 0.90; interrater ICC, 0.80). Fibrosis measures had ICCs of 0.70–0.87. Conclusions After extensive preparation among a group of experienced pathologists, we demonstrated improved reliability of multiple existing histologic NAFLD indices and fibrosis staging systems. Hepatocyte ballooning and MDBs most strongly correlated with disease activity and were used for the expanded NAS. Further validation including evaluation of responsiveness is required.

Summary Drug-induced liver injury (DILI) is often caused by innate and adaptive host immune responses. Characterization of inflammatory infiltrates in the liver may improve understanding of the underlying pathogenesis of DILI. This study aimed to enumerate and characterize leucocytes infiltrating liver tissue from subjects with acute DILI (n = 32) versus non-DILI causes of acute liver injury (n = 25). Immunostains for CD11b/CD4 (Kupffer and T helper cells), CD3/CD20 (T and B cells) and CD8/CD56 [T cytotoxic and natural killer (NK) cells] were evaluated in biopsies from subjects with acute DILI, either immunoallergic (IAD) or autoimmune (AID) and idiopathic autoimmune (AIH) and viral hepatitis (VH) and correlated with clinical and pathological features. All biopsies showed numerous CD8+ T cells and macrophages. DILI cases had significantly fewer B lymphocytes than AIH and VH and significantly fewer NK cells than VH. Prominent plasma cells were unusual in IAD (three of 10 cases), but were associated strongly with AIH (eight of nine) and also observed in most with AID (six of nine). They were also found in five of 10 cases with VH. Liver biopsies from subjects with DILI were characterized by low counts of mature B cells and NK cells in portal triads in contrast to VH. NK cells were found only in cases of VH, whereas AIH and VH both showed higher counts of B cells than DILI. Plasma cells were associated most strongly with AIH and less so with AID, but were uncommon in IAD.