Autoimmune Hepatitis

Slide 1 · Autoimmune Hepatitis

Immune mechanisms · Morphology · Integrated diagnosis

Pathology lecture

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning objectives: Connect mechanism, biopsy and diagnosis

Explain HLA association and the lymphocyte–plasma cell response.

Recognize interface activity, plasma cells, necrosis and fibrosis.

Integrate serology, serum IgG, biopsy and exclusion of mimics.

Anticipate clinical course, overlap syndromes and treatment response.

Slide 3 · Autoimmune hepatitis: The defining concept

Chronic progressive immune-associated hepatocellular inflammation

Genetic susceptibility and autoantibodies are common.

Immunosuppressive treatment often induces remission.

Untreated disease may progress to cirrhosis or death.

Slide 4 · Four complementary diagnostic evidence streams

Autoantibodies

ANA, SMA, LKM-1 or other relevant reactivity

IgG

Increased serum immunoglobulin G

Histology

Supportive hepatitis pattern on liver biopsy

Exclusion

Alternative causes systematically assessed

No single stream independently establishes the diagnosis.

Slide 5 · Female predominance and population distribution

Women account for approximately 78% of cases summary.

HLA associations vary across populations; Susceptibility is not uniform.

AIH can occur across a wide range of clinical ages and presentations.

Slide 6 · Genetic predisposition: HLA associations

European populations

HLA-DR3 association

Japanese populations

HLA-DR4 association

South American populations

HLA-DRB1 association reported

Association indicates susceptibility, not a stand-alone diagnostic test.

Slide 7 · Proposed triggers versus established uncertainty

Proposed triggers

Viral infection

Drugs or toxins

Vaccination

What remains uncertain

Target autoantigens are not defined in the source.

The initiating loss of tolerance is not established.

Temporal associations should not be interpreted as demonstrated causality.

Slide 8 · Conceptual sequence of hepatocellular immune injury

Predisposition

HLA-linked susceptibility

Immune activation

CD4⁺ and CD8⁺ T-cell involvement

B-cell response

Plasma cells and autoantibodies

Liver response

Interface and lobular hepatitis

Exact causal links between these elements remain incompletely understood.

Slide 9 · CD4⁺ helper T cells: Coordinating the response

The hepatic infiltrate is predominantly enriched in CD4⁺ helper T cells.

Helper T-cell activity supports B-lymphocyte activation.

Activated B cells differentiate into antibody-secreting plasma cells.

Cellular composition does not by itself prove the mechanism of injury.

Slide 10 · CD8⁺ cytotoxic T cells: Localization at the interface

CD8⁺ T cells are identified at the portal–parenchymal interface.

Their location corresponds to zones of interface hepatocyte injury.

The precise contribution of cytotoxicity to tissue injury is not fully defined.

Slide 11 · Plasma cells and autoantibody production

CD4⁺ helper T cell

B-cell activation signals

B lymphocyte

Differentiation into plasma cell

Plasma cell

Production of circulating autoantibodies

Serologic detectability is not equivalent to direct antibody-mediated cytotoxicity.

Slide 12 · Autoantibodies are diagnostic clues—not severity meters

Antibody positivity supports an immune-associated phenotype

Measured titers correlate poorly with disease severity or outcome.

Autoantibodies can also accompany chronic viral hepatitis and steatohepatitis.

A small subset has seronegative autoimmune hepatitis.

Slide 13 · Drug-associated autoimmune hepatitis-like injury

Minocycline, nitrofurantoin and α-methyldopa are textbook examples.

Drugs may induce both autoantibodies and hepatocellular injury.

The phenotype can imitate idiopathic autoimmune hepatitis.

Recovery after withdrawal of the culprit drug supports a drug-related process.

Slide 14 · Portal–lobular architecture: Where interface injury occurs

Portal tract

Anatomic orientation

A portal tract lies adjacent to periportal hepatocyte plates.

Interface activity involves inflammatory cells extending into hepatocytes at the junction.

Schematic — not a histologic specimen

Slide 15 · The microscopic signature: Interface hepatitis

Portal tract

Interpretive point

Interface inflammation is characteristic in AIH but is not specific.

Similar activity occurs in several other hepatitis etiologies.

Schematic — not a histologic specimen

Slide 16 · Plasma-cell-rich inflammation: An important clue

Portal tract

Microscopic pattern

Plasma cells may occur in conspicuous clusters.

Assess their density together with the overall pattern and clinical findings.

Schematic — not a histologic specimen

Slide 17 · Plasma cells: Significance and limitations

Numerous clustered plasma cells are typical of AIH.

The inflammatory infiltrate also includes lymphocytes.

Plasma-cell prominence strengthens suspicion but does not establish etiology.

Pattern recognition requires assessment of portal and lobular compartments.

Slide 18 · Emperipolesis: An inflammatory cell within a hepatocyte

Portal tract

Definition

Lymphocytes or plasma cells may lie within the hepatocyte cytoplasm.

This finding is not pathognomonic and should not be required in isolation.

Schematic — not a histologic specimen

Slide 19 · Hepatocyte rosettes: An architectural regenerative pattern

Portal tract

Morphologic relationship

Hepatocytes may form a circular arrangement around a dilated canaliculus.

this is described as a regenerative response.

Schematic — not a histologic specimen

Slide 20 · Confluent necrosis: Severity spans several zones

Perivenular

Groups of hepatocytes lost near central venules

Panacinar

Extensive involvement of an entire acinus

Bridging

Confluent injury connects vascular landmarks

Necrosis distribution helps characterize severity and pattern.

Slide 21 · Perivenular confluent necrosis

Groups of injured hepatocytes can be centered on perivenular regions.

This pattern demonstrates that injury is not restricted to portal interfaces.

Assess the remaining lobular architecture for associated inflammation.

Slide 22 · Panacinar necrosis

Confluent hepatocyte death can extend across an entire acinus.

Extensive hepatocellular loss corresponds to severe active injury.

Acute clinical presentation may occur despite underlying chronic disease.

Slide 23 · Bridging necrosis is not bridging fibrosis

Bridging necrosis

Confluent hepatocyte loss connects vascular structures.

It reflects active and potentially severe injury.

Bridging fibrosis

Collagenous septa link architectural landmarks.

It indicates chronic remodeling rather than simply active cell loss.

Slide 24 · Persistent autoimmune injury can culminate in cirrhosis

Ongoing hepatitis

Portal and lobular injury persists

Fibrogenic response

Hepatocyte loss and chronic inflammation

Architectural change

Fibrosis, bridging and cirrhosis

Fibrosis may already be present before overt symptoms appear.

Slide 25 · Fibrosis at the first biopsy may reveal delayed recognition

Most cases already show some fibrosis when first examined.

Fibrosis may increase with continuing disease activity.

Asymptomatic or apparently acute disease may coexist with advanced scarring.

Slide 26 · Burnt-out cirrhosis: Little activity does not exclude AIH

Advanced scarring may remain after active inflammation becomes limited

Subclinical autoimmune injury can precede recognition for years.

A biopsy with cirrhosis and little hepatitis may obscure the original etiology.

Interpret tissue changes in the context of history and serology.

Slide 27 · Liver biopsy: Active injury versus accumulated damage

Feature

What it describes

Interpretive consequence

Interface hepatitis

Active hepatocyte injury at the border

Indicates ongoing inflammation

Lobular activity

Parenchymal necroinflammation

Can dominate acute presentations

Confluent necrosis

Contiguous hepatocyte loss

Indicates substantial injury

Fibrosis / cirrhosis

Architectural scar formation

Reflects cumulative disease

Slide 28 · Clinical spectrum: One disease, several entry points

Incidental discovery

Elevated transaminases without symptoms

Insidious course

Fatigue, anorexia, nausea, abdominal pain

Acute presentation

Hepatitis resembling viral or drug injury

Advanced disease

Fibrosis, cirrhosis or liver failure

Slide 29 · Asymptomatic autoimmune hepatitis

Transaminase elevation may be found during routine testing.

Absence of symptoms does not reliably exclude fibrosis.

Histologic assessment may reveal substantial longstanding injury.

Slide 30 · Insidious symptoms and their pathologic context

Fatigue, anorexia, nausea and abdominal pain are common nonspecific symptoms.

These manifestations overlap with many inflammatory liver diseases.

Laboratory, serologic and tissue evaluation are necessary for attribution.

Slide 31 · Acute autoimmune hepatitis

Initial symptoms and laboratory abnormalities may resemble acute viral hepatitis.

Drug-induced liver injury is another major clinical mimic.

Underlying fibrosis may demonstrate pre-existing, unrecognized chronic disease.

Slide 32 · Acute liver failure is within the disease spectrum

An apparently acute attack can represent severe AIH

Confluent, panacinar or bridging necrosis may accompany severe activity.

The source recognizes acute liver failure as a possible presentation.

Prompt etiologic discrimination is clinically consequential.

Slide 33 · Clinical acuity does not equal histologic chronicity

Abrupt presentation

Symptoms develop rapidly.

Hepatocellular injury may be extensive.

Other acute hepatitides require exclusion.

Pre-existing disease

Fibrosis can be present on the first biopsy.

Cirrhosis may already be established.

The clinical onset is not necessarily disease onset.

Slide 34 · Associated autoimmune diseases

Type 1 diabetes mellitus can coexist with AIH.

Autoimmune thyroiditis is another recognized association.

Celiac disease (celiac sprue) is also described.

Comorbidity raises suspicion but does not constitute diagnostic proof.

Slide 35 · Overlap with autoimmune cholestatic diseases

AIH–PBC overlap

Combines hepatitic features of AIH with unequivocal evidence of primary biliary cholangitis.

AIH–PSC overlap

Combines AIH with evidence of primary sclerosing cholangitis.

The source notes PSC overlap particularly in children.

Slide 36 · Overlap diagnosis requires two established components

Serologic, biochemical and/or histologic evidence must substantiate both diseases.

An isolated AMA or nonspecific cholestasis is not sufficient by itself.

The second component may only become apparent months or years later.

Slide 37 · Four diagnostic pillars must be interpreted together

Serology

Autoantibody profile and reliability

Immune activity

Serum IgG concentration

Biopsy

Compatible inflammatory pattern

Exclusion

Viral and drug-related alternatives

A composite assessment is more robust than any isolated positive test.

Slide 38 · Type 1 autoimmune hepatitis: Typical serologic profile

Antibody

Interpretation in context

ANA

Common in type 1 AIH; not disease-specific

Anti–smooth muscle (SMA/ASMA)

Common in type 1 AIH; used in scoring

Anti-SLA/LP

Additional autoantibody that can support AIH

AMA

Occasionally detected; more characteristic of PBC

Slide 39 · Anti-SLA/LP: An additional supportive autoantibody

Anti–soluble liver antigen/liver-pancreas antibodies may occur in AIH.

In the original simplified system, positive SLA contributes 2 antibody points.

The total autoantibody domain is capped at 2 points.

Other liver diseases still require independent assessment.

Slide 40 · Type 2 autoimmune hepatitis: Defining antibodies

Marker

Relevant interpretation

Anti–LKM-1

Recognizes CYP2D6; characteristic of type 2 disease

Anti–liver cytosol-1 (LC1)

Another characteristic antibody in type 2 disease

Clinical setting

Type 2 AIH is described more often in children

Morphology and natural history

Broadly similar to type 1 AIH

Slide 41 · Type 1 versus type 2 autoimmune hepatitis

Type 1

More common subtype.

ANA and/or SMA are typical.

Anti-SLA/LP may occur.

Type 2

More frequent in children.

Anti-LKM-1 and anti-LC1 are characteristic.

Other clinical and histologic findings broadly overlap.

Subtype assignment rests on the antibody phenotype, not unique tissue morphology.

Slide 42 · Serum IgG: Useful but not a stand-alone diagnosis

Increased serum IgG provides independent diagnostic support

Hypergammaglobulinemia often accompanies autoimmune hepatitis.

In the simplified score, IgG contributes 0, 1 or 2 points.

A total diagnosis still requires evaluation of morphology and mimics.

Slide 43 · Seronegative autoimmune hepatitis

A small subset of cases lacks detectable conventional autoantibodies.

A negative screening panel therefore cannot absolutely exclude AIH.

Serum IgG, histologic activity and exclusion of other causes remain important.

Slide 44 · A positive autoantibody is not specific to AIH

Supports AIH when concordant

Raised IgG

Compatible biopsy

Competing causes excluded

Potentially misleading alone

Steatohepatitis

Chronic hepatitis B

Chronic hepatitis C

Antibody titers also have limited correlation with severity and outcome.

Slide 45 · A disciplined exclusion strategy

Identify hepatitis

Biochemical or histologic hepatocellular injury

Review exposures

Medications, supplements and toxins

Exclude viral causes

Appropriate clinical/virologic evaluation

Integrate biopsy

Activity, chronicity and competing patterns

Slide 46 · When drug injury resembles autoimmune hepatitis

Ask about minocycline, nitrofurantoin and α-methyldopa exposure.

An autoimmune-like drug reaction can include circulating autoantibodies.

Drug discontinuation typically leads to clinical recovery in the source.

The exposure–response relationship is essential to interpretation.

Slide 47 · Histology supports diagnosis but is not pathognomonic

Interface activity, lobular hepatitis and plasma cells form a supportive pattern.

Acute and chronic hepatitis of other causes can look similar.

Severe necrosis, rosettes or emperipolesis cannot replace clinical correlation.

Histology should also assess fibrosis and alternative disease features.

Slide 48 · Simplified AIH score: Antibody and IgG domains

Domain

Finding

Points

Autoantibodies

ANA or SMA ≥1:40

1

Autoantibodies

ANA/SMA ≥1:80; LKM ≥1:40; or SLA positive

2 (max)

Serum IgG

Above upper limit of normal

1

Serum IgG

>1.10 × upper limit of normal

2

Slide 49 · Simplified AIH score: Tissue and viral-exclusion domains

Domain

Finding

Points

Histology

Likely/typical for AIH

2

Histology

Possible/compatible with AIH

1

Histology

Unlikely/atypical for AIH

0

Exclusion of viral hepatitis

No viral hepatitis identified

2

Slide 50 · 2022 histologic consensus: Likely versus possible AIH

Likely AIH (2 points)

Lymphocytic/lymphoplasmacytic portal or lobular inflammation.

More than mild interface or lobular activity.

No convincing features of another liver disorder.

Possible AIH (1 point)

Mild interface or lobular inflammatory activity; OR

Supportive hepatitis features coexist with findings suggesting another disease.

Slide 51 · Diagnostic score thresholds

Probable AIH ≥ 6 points · Definite AIH ≥ 7 points

Original simplified score has a maximum of 8 points.

Autoantibody domain contributes no more than 2 points in total.

Clinical judgment remains necessary if the score is discordant.

Simplified scoring: Hennes et al. 2008; Histology updated 11e.

Slide 52 · Common diagnostic scoring pitfalls

Do not add multiple autoantibody points beyond the domain maximum of 2.

Distinguish 1-point from 2-point IgG thresholds precisely.

Do not label every interface hepatitis specimen as typical AIH.

Treat missing viral exclusion as a genuine evidentiary gap.

Slide 53 · Differential diagnosis: Interpret the entire pattern

Alternative

Why it may mimic AIH

Discriminator

Viral hepatitis

Active portal/lobular hepatitis; antibodies may occur

Virologic evaluation

Drug-induced liver injury

Autoimmune-like serology and hepatocellular injury

Medication history; withdrawal

Steatohepatitis

Chronic injury and nonspecific autoantibodies

Competing morphologic pattern

PBC / PSC overlap

Mixed hepatitic and cholestatic features

Independent evidence of both

Slide 54 · Integrated diagnostic workflow for suspected AIH

Clinical suspicion

Pattern, onset, drug history

Serum studies

Autoantibodies and IgG

Evaluate mimics

Viral and drug etiologies

Biopsy synthesis

Activity, pattern, fibrosis

Use a simplified score as an aid, not a substitute for synthesis.

Slide 55 · Immunosuppressive therapy targets ongoing activity

Active AIH

Immune-associated hepatocellular injury

Treatment

Prednisone ± azathioprine

Response

Biochemical/clinical remission

Long-term goal

Limit progression and relapse

Therapeutic details are summarized from the textbook, not individualized prescribing.

Slide 56 · Treatment response: An important aspect of disease behavior

Remission occurs in approximately 80–90% with standard therapy

Prednisone, with or without azathioprine, as first-line therapy.

Remission generally occurs within 12 months in responding patients.

Treatment response is supportive context, not proof of initial diagnosis.

Slide 57 · Steroid intolerance and alternatives

The source notes other immunosuppressants when glucocorticoids are not tolerated.

Selection depends on a specialist assessment and patient-specific factors.

An unfavorable drug effect must be distinguished from ongoing autoimmune activity.

Slide 58 · Why incomplete response and relapse matter

Incomplete control

Continued inflammatory activity

Recurrent episodes

Repeated hepatocyte injury

Cumulative damage

Higher cirrhosis risk

Long-term concern

Hepatocellular carcinoma risk

Slide 59 · Advanced AIH: Cirrhosis and hepatocellular carcinoma

Cirrhosis can be present even at first diagnosis.

Incomplete response or multiple relapses increases progression risk.

Hepatocellular carcinoma is a recognized long-term concern in this group.

Slide 60 · Liver transplantation: Textbook outcome figures

Liver transplantation may be necessary in patients with advanced cirrhosis.

Approximately 75% survival at 10 years after transplant.

Disease recurrence is reported in approximately 20% of recipients.

These are textbook summary figures; They are not individual prognostic estimates.

Slide 61 · Case 1: Applying the simplified AIH score

Case vignette

Illustrative scenario: ANA 1:160, IgG 1.3× upper limit of normal, viral hepatitis excluded, and biopsy judged “possible AIH” under updated histologic categories.

Task

Compute the score.

What diagnostic category does it support?

Slide 62 · Case 1: Transparent point allocation

Autoantibody

ANA ≥1:80 → 2

Serum IgG

>1.10× ULN → 2

Histology

Possible AIH → 1

Viral exclusion

Confirmed → 2

Total: 7 points — definite AIH by the simplified score.

Slide 63 · Case 2: The medication-history trap

Case vignette

Illustrative scenario: Hepatocellular injury, increased IgG and positive ANA emerge during nitrofurantoin therapy. The biopsy shows interface hepatitis and plasma cells.

Task

What competing diagnosis must be addressed before labeling idiopathic AIH?

Slide 64 · Case 2: Interpretation before disease labeling

Nitrofurantoin is a documented trigger of autoimmune-like drug liver injury.

The serology and biopsy do not by themselves establish idiopathic AIH.

Drug exposure timing and clinical course after withdrawal are essential.

Slide 65 · Case 3: Cholestatic overlap versus incidental markers

Case vignette

Illustrative scenario: A patient with AIH has an antimitochondrial antibody detected and a persistent cholestatic biochemical pattern.

Task

What additional evidence would justify diagnosing an AIH–PBC overlap syndrome?

Slide 66 · Case 3: Do not infer overlap from one marker

Overlap requires unequivocal evidence supporting each disease component.

Biochemical and serologic findings must be assessed alongside morphology.

Longitudinal reassessment may reveal a second component later.

Slide 67 · Recognition checklist: AIH on a liver biopsy

Evaluate

What to document

Inflammation

Portal and lobular distribution; interface activity

Cell composition

Lymphocytes and prominence/clustered plasma cells

Hepatocyte injury

Apoptotic/confluent necrosis; extent and topography

Regeneration

Rosettes if present; not obligatory

Chronicity

Fibrosis / cirrhosis; activity may be low in burnt-out stage

Competing pattern

Evidence that favors viral, drug or cholestatic disease

Slide 68 · Integrated synthesis: Four indispensable ideas

AIH is diagnosed by convergence—not a single antibody or biopsy sign

T-cell and plasma-cell responses produce characteristic hepatitis patterns.

Presentations range from incidental elevation to acute liver failure.

Exclude viral and drug injury; Use IgG, serology and histology together.

Control of immune activity changes the natural history.

Slide 69 · Selected references

Robbins, Cotran & Kumar. Pathologic Basis of Disease. 11th ed. 2026. Chapter 18, pp. 763–764.

Hennes EM, Zeniya M, Czaja AJ, et al. Simplified criteria for the diagnosis of autoimmune hepatitis. Hepatology. 2008;48:169–176.

Lohse AW, Sebode M, Bhathal PS, et al. Consensus recommendations for histological criteria of autoimmune hepatitis. Liver Int. 2022;42:1058–1069.