Hepatocellular Adenoma

Slide 1 · Hepatocellular Adenoma

Molecular pathology, morphology and clinical consequences

Benign hepatocytic neoplasm

Four molecularly defined subtypes

Hemorrhage and malignant transformation risk

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning goals

Define hepatocellular adenoma and recognize its typical clinical context.

Connect HNF1A, IL-6/JAK–STAT, Wnt/β-catenin and GLI1 alterations to characteristic phenotypes.

Interpret its gross, microscopic and immunophenotypic features.

Distinguish clinically relevant subtypes and management risk factors.

Slide 3 · The organizing principle: A benign but heterogeneous tumor

Neoplastic hepatocytes

Subtype-specific molecular alteration

Distinct morphology and biomarkers

Different clinical risks

Adenoma is not a single biological risk category.

Slide 4 · What makes this lesion an adenoma?

Identity

Clonal, benign neoplasm of hepatocytes.

Mass-forming lesion rather than a reactive hepatic nodule.

Usually discrete within surrounding liver.

Consequences

Can produce symptoms despite benign histology.

Certain subtypes carry malignant transformation risk.

Hemorrhage can be life-threatening.

Slide 5 · A typical patient profile

Hepatocellular adenoma most often occurs in young females.

It is strongly linked with oral contraceptive exposure.

Anabolic steroid exposure represents another important association.

The prevalence pattern is changing with obesity and metabolic syndrome.

Slide 6 · Exogenous hormone association

Oral contraceptive exposure

Susceptible hepatocellular population

Hepatocellular adenoma

Exposure cessation may be considered

Exposure is a clinical association; Subtype-specific mutations define the lesions.

Slide 7 · Anabolic steroids: Why the history matters

Epidemiologic link

A recognized risk factor for hepatocellular adenoma.

Particularly relevant to β-catenin–activated lesions.

Clinical evaluation

Ask explicitly about anabolic steroid use.

Exposure modification matters in selected low-risk lesions.

Male sex is an independent surgical consideration.

Slide 8 · Obesity and metabolic syndrome

The reported rise in adenoma incidence is presumed to relate partly to increasing metabolic disease.

Inflammatory adenoma is associated with obesity and metabolic syndrome.

Metabolic association does not establish a molecular subtype by itself.

Interpret epidemiologic context together with morphology and markers.

Slide 9 · Solitary disease versus hepatic adenomatosis

Single lesion

A discrete hepatic mass composed of neoplastic hepatocytes.

May be found incidentally or following symptoms.

Multiple lesions

Multiple adenomas can occur in familial or acquired settings.

“Hepatic adenomatosis” denotes 10 or more tumors.

The designation concerns multiplicity, not a fifth molecular subtype.

Slide 10 · Why molecular classification is essential

Four molecular subtypes are recognized in the source text.

They have distinct mechanisms, morphologies and immunophenotypes.

Frequency and sex distribution vary among subtypes.

Hemorrhagic and malignant risks are not uniform.

Slide 11 · Four molecular categories

Molecularly distinct hepatocellular neoplasms

HNF1α-inactivated

HNF1A loss of function

Inflammatory

Gp130 / JAK–STAT

β-catenin–activated

Wnt pathway activation

Sonic hedgehog

GLI1 fusion

Slide 12 · Subtype prevalence and clinical associations

Molecular subtype

Source-reported frequency

Dominant clinical pattern

HNF1α-inactivated

30–35%

Strong female predilection

Inflammatory

35–50%

Female; obesity / metabolic syndrome

β-catenin–activated

Not specified

Steroids; nearly 40% male

Sonic hedgehog

Not specified

Prominent hemorrhage propensity

Slide 13 · HNF1A is a hepatocyte transcriptional regulator

HNF1A gene

HNF1α transcription factor

Regulation of hepatocyte genes

Subtype-specific downstream phenotype

Inactivation of the regulator affects multiple hepatocellular products.

Slide 14 · HNF1α-inactivated adenoma: Molecular lesion

Loss-of-function mutations affect HNF1A.

HNF1α normally regulates numerous hepatocyte-expressed genes.

The altered gene-regulatory program is reflected in characteristic steatosis and LFABP loss.

This subtype has minimal malignant transformation risk.

Slide 15 · Somatic and germline HNF1A alterations

Hepatic tumor

HNF1A loss of function defines the subtype.

Most lesions are not identified solely from a germline history.

Inherited association

Heterozygous germline HNF1A mutations cause autosomal dominant MODY type 3.

They are associated with approximately 10% of HNF1α-inactivated adenomas.

Slide 16 · The HNF1α–steatosis relationship

Loss of HNF1α function

Changed hepatocyte gene expression

Prominent fat within tumor hepatocytes

Characteristic morphologic clue

Steatosis is a characteristic association, not proof of genotype in isolation.

Slide 17 · Interpreting LFABP immunostaining

Tumor hepatocytes

LFABP expression lost

Adjacent normal hepatocytes

LFABP expression preserved

Schematic — not a tissue specimen

Internal positive control in adjacent liver makes loss in the tumor interpretable.

Slide 18 · HNF1α-inactivated tumors: Clinicopathologic signature

Constitute approximately one-third of hepatocellular adenomas.

Strong female predominance is typical.

Intratumoral steatosis and LFABP loss support subtype assignment.

Malignant transformation risk is characterized as minimal.

Slide 19 · Inflammatory adenoma: Pathway driver

Acquired activating gp130 alteration

Constitutive JAK–STAT signaling

Acute-phase protein overexpression

Inflammatory adenoma phenotype

Gp130 is a coreceptor in the IL-6 signaling system.

Slide 20 · Gp130 and IL-6 signaling: Key distinction

Inflammatory adenomas are linked to acquired activating mutations in gp130.

Gp130 functions as a coreceptor for interleukin-6.

Constitutive signaling activates the downstream JAK–STAT pathway.

The molecular effect explains increased expression of acute-phase proteins.

Slide 21 · Why CRP and serum amyloid A are elevated

JAK–STAT activation

Hepatocellular inflammatory response

CRP and serum amyloid A overexpression

Positive tumor-cell immunostaining

These proteins are phenotypic markers of pathway activation.

Slide 22 · Inflammatory immunophenotype

Tumor hepatocytes

CRP / SAA overexpressed

Surrounding hepatocytes

Variable and generally lower expression

Schematic — not a tissue specimen

The positive tumor-cell signal can support subtype classification when interpreted with morphology.

Slide 23 · Inflammatory adenoma: Morphologic features

Sinusoidal dilatation is characteristic.

Fibrous septa may be present within the lesion.

A ductular reaction can occur.

The latter two features can mimic focal nodular hyperplasia.

Slide 24 · Inflammatory adenoma: Clinical setting

Common context

Women predominate.

Obesity and metabolic syndrome are associated.

Accounts for 35–50% of cases.

Risk nuance

A subset additionally harbors β-catenin activation.

Overlap may increase malignant transformation risk.

A purely inflammatory label should not hide β-catenin-associated risk.

Slide 25 · Inflammatory/β-catenin overlap

Inflammatory subtype

Additional β-catenin–activating mutation

Combined signaling phenotype

Higher malignant transformation risk

Source reports β-catenin activation in about 10% of inflammatory adenomas.

Slide 26 · Wnt/β-catenin pathway context

Wnt pathway activation

Stabilized β-catenin signaling

Nuclear β-catenin localization

Wnt target-gene expression

Schematic sequence shows the causal relationship stated by the source.

Slide 27 · β-catenin–activated adenoma: Affected genes

CTNNB1 encodes β-catenin and may harbor activating mutations.

Other alterations can affect Wnt regulatory components such as APC or AXIN2.

Constitutive signaling can produce nuclear β-catenin accumulation.

The precise CTNNB1 exon is important for risk stratification.

Slide 28 · CTNNB1 exon 3 versus exons 7–8

Exon 3

High-level β-catenin activation.

High risk of malignant transformation into HCC.

Greater concern when atypical morphology coexists.

Exons 7 or 8

Lower-level β-catenin activation.

Low association with HCC in the source.

Not biologically interchangeable with exon 3.

Slide 29 · Why “β-catenin positive” is not enough

Normal β-catenin is associated with cell membranes.

Pathway activation may shift the staining pattern toward nuclei.

Strong nuclear localization is reported in β-catenin–mutated adenomas.

Staining and exon-specific genotype must be distinguished.

Slide 30 · Nuclear β-catenin: Conceptual immunostain

Resting localization

Predominantly membranous signal

Activated pathway

Tumor-cell nuclear signal

Schematic — not a tissue specimen

A change in subcellular compartment supports pathway activation; This is a schematic, not a photomicrograph.

Slide 31 · β-catenin activation and atypical morphology

Cytologic or architectural atypia may occur within the adenoma.

Areas of overt hepatocellular carcinoma can be present.

An atypical focus therefore warrants attention to malignant transformation.

Risk assessment cannot rely on overall benign designation alone.

Slide 32 · β-catenin subtype: Clinical associations

Hormonal exposure

Anabolic steroid use is a known risk factor.

Exposure history supports clinicopathologic interpretation.

Sex distribution

Nearly 40% of β-catenin–activated adenomas occur in males.

Male sex carries a separate resection recommendation.

Slide 33 · Sonic hedgehog adenoma: Genetic mechanism

GLI1 gene fusion

Sonic hedgehog pathway activation

Distinct adenoma subtype

Marked hemorrhage propensity

The source identifies a fusion-driven signaling mechanism.

Slide 34 · Why sonic hedgehog adenoma matters

A recently characterized hepatocellular adenoma subtype.

GLI1 fusion genes activate the sonic hedgehog pathway.

Its standout reported clinical phenotype is hemorrhage.

Biological risk is not captured by malignant transformation alone.

Slide 35 · Molecular lesions and their phenotypic readouts

Subtype

Driver / pathway

Feature that helps recognition

HNF1α-inactivated

HNF1A loss

Steatosis; LFABP loss

Inflammatory

gp130 → JAK–STAT

CRP / SAA upregulation

β-catenin–activated

CTNNB1 / Wnt

Nuclear β-catenin; atypia

Sonic hedgehog

GLI1 fusion

High hemorrhage propensity

Slide 36 · Do not equate subtype frequency with risk

More frequent categories

Inflammatory and HNF1α-inactivated lesions comprise substantial proportions.

Their biology and clinical risks differ.

Risk-enriched categories

Exon 3 β-catenin activation is linked to high malignant risk.

Sonic hedgehog activation is linked to bleeding.

Inflammatory + β-catenin overlap deserves separate attention.

Slide 37 · Gross morphology: The discrete hepatic mass

Schematic gross cross-section

The neoplasm forms a distinct mass.

Hemorrhage may change its gross appearance.

Gross inspection cannot specify every molecular subtype.

Slide 38 · Microscopic architecture: Thin hepatocyte plates

Neoplastic hepatocytes form one- to two-cell-thick plates.

Overall architecture may resemble benign hepatic tissue.

The lesion has a distinctive vascular and portal-tract organization.

Architecture must be interpreted along with the clinical and molecular context.

Slide 39 · Schematic: Normal liver versus adenoma

PT

A

Normal liver

Portal tracts with bile ducts

Adenoma

Arterial supply; No normal portal tracts

PT = portal tract | A = artery | Schematic — not a photomicrograph

The comparison depicts a diagnostic organizational difference, not actual histologic tissue.

Slide 40 · The arterial supply is a structural clue

Large arteries may course through scant fibrous stroma.

The lesion lacks normal portal tracts.

The arrangement differs from ordinary hepatic lobular anatomy.

An isolated artery is not sufficient by itself for definitive classification.

Slide 41 · What is absent within the adenoma?

Present / typical

Neoplastic hepatocyte plates.

Arterial blood supply.

Limited interstitial fibrous stroma.

Absent / expected

Normal portal tracts.

Interlobular bile ducts as components of portal tracts.

Ordinary portal–lobular organization.

Slide 42 · A morphology-first review sequence

Confirm hepatocytic lesion

Assess plates and vascular pattern

Look for steatosis / dilated sinusoids / atypia

Interpret subtype immunostains

A diagnostic reading sequence inferred from source morphology and markers.

Slide 43 · Steatosis points toward HNF1α inactivation

HNF1α-mutated adenomas commonly contain conspicuous lipid.

The fat resides in the neoplastic hepatocytes.

Loss of LFABP strengthens the subtype interpretation.

Steatosis alone is not a complete molecular diagnosis.

Slide 44 · Sinusoidal dilatation points toward inflammation

Dilated sinusoids favor inflammatory morphology.

Fibrous septa and ductular reaction may coexist.

These findings can overlap with focal nodular hyperplasia.

CRP or SAA tumor-cell staining provides a molecularly linked clue.

Slide 45 · Atypia points to a high-risk adenoma phenotype

β-catenin–mutated adenomas may show architectural abnormality.

Cytologic atypia raises concern for progression or an overt HCC component.

Atypia is not a uniform feature of all hepatocellular adenomas.

Interpret morphologic atypia alongside β-catenin status.

Slide 46 · Diagnostic subtype IHC: What each signal means

Readout

Pattern in relevant subtype

Interpretation

LFABP

Loss in HNF1α-inactivated tumor

Downstream of HNF1α deficiency

CRP / SAA

Overexpressed in inflammatory tumor

JAK–STAT-associated response

β-catenin

Nuclear localization in activated tumor

Wnt pathway activation

Slide 47 · Why an internal staining control matters

Tumor compartment

LFABP absence can be diagnostic evidence.

Compare lesional staining with surrounding nonneoplastic hepatocytes.

Nonneoplastic compartment

Preserved LFABP provides a positive internal control.

An uninterpretable negative stain cannot establish true loss.

Slide 48 · Inflammatory adenoma can resemble FNH

The adenoma may contain fibrous septa and ductular reaction.

FNH also contains fibrous septa and prominent ductular reaction.

An overlapping histologic feature is not an identical pathogenic process.

Use the lesion-wide pattern plus immunophenotype to distinguish them.

Slide 49 · Hepatocellular adenoma versus focal nodular hyperplasia

Feature

Adenoma

FNH

Biology

Benign neoplasm

Benign nonneoplastic mass

Typical gross form

Discrete tan mass

Often stellate central scar

Bile ducts / portal areas

Normal portal tracts absent

Prominent ductular reaction in septa

Subtype markers

LFABP / CRP / SAA / β-catenin

Map-like GS staining

Slide 50 · The FNH map-like GS pattern

In FNH

GS immunoreactivity forms characteristic anastomosing map-like areas.

The pattern reflects unusual hepatic organization.

In adenoma

Subtype classification relies on different pathway-linked features.

FNH-like septa in inflammatory adenoma do not themselves establish FNH.

Slide 51 · Adenoma versus hepatocellular carcinoma

Diagnostic domain

Hepatocellular adenoma

Hepatocellular carcinoma

Biology

Benign neoplasm

Malignant epithelial tumor

Architecture

Usually thin hepatocyte plates

May show thick plates / sheets

Atypia

May be present in high-risk subtype

Can be pronounced

Relation

Some lesions may transform

May arise within adenoma

Slide 52 · Malignant transformation: What the source establishes

Hepatocellular carcinoma can arise within hepatocellular adenoma.

Risk is particularly important in β-catenin–activated lesions.

CTNNB1 exon 3 activation is associated with greater malignant risk.

Inflammatory adenomas with additional β-catenin activation also carry increased risk.

Slide 53 · Morphologic warning sequence

β-catenin–activated adenoma

Cytologic / architectural atypia

Area of overt HCC may emerge

Escalated clinical concern

A possible pathologic relationship, not an obligatory progression in every case.

Slide 54 · Clinical presentation: Incidental discovery

Lesions may be detected unexpectedly on liver imaging.

An asymptomatic course does not eliminate future hemorrhage risk.

Clinical history and tumor characteristics are needed for stratification.

Imaging establishes detection; The source does not provide a definitive subtype imaging algorithm.

Slide 55 · Why pain may develop

Adenoma within liver

Symptomatic lesion or hemorrhagic necrosis

Abdominal pain

Clinical evaluation

The source describes abdominal pain or hemorrhagic necrosis as presentations.

Slide 56 · Hemorrhagic necrosis: A clinically important change

Bleeding may occur within a hepatocellular adenoma.

Hemorrhagic necrosis can make a previously silent lesion symptomatic.

Rupture can cause substantial intraperitoneal blood loss.

Clinical urgency is determined by bleeding consequences, not benign histology.

Slide 57 · Rupture of an adenoma is a surgical emergency

Intralesional hemorrhage

Adenoma rupture

Massive abdominal bleeding

Emergency surgical management

This is the major acute complication highlighted by Robbins.

Slide 58 · Two distinct adverse outcomes

Hemorrhage

Can occur without malignant transformation.

Sonic hedgehog subtype has marked hemorrhage propensity.

Rupture may trigger a surgical emergency.

Malignant transformation

Linked especially to β-catenin activation.

Exon 3 activation is a high-risk molecular feature.

Treatment choices must consider both outcomes.

Slide 59 · Risk factors that affect the management recommendation

Feature

Implication in the textbook

Male patient

Resection recommended

β-catenin–activated adenoma

Resection recommended

Lesion ≥5 cm

Resection recommended

Small lesion without β activation

Observation and exposure cessation may suffice

Slide 60 · The 5-cm threshold: What it means

Robbins recommends resection for adenomas 5 cm or larger.

The rationale includes both hemorrhage and malignant risk.

The threshold is one consideration, not a substitute for molecular and sex-related risk.

This is a textbook management summary, not a complete contemporary treatment guideline.

Slide 61 · Male patients require separate consideration

The textbook recommends resection for hepatocellular adenoma in male patients.

This applies regardless of other high-risk features.

The sex-based recommendation should not be conflated with the frequency of adenomas in males.

Clinical decisions are individualized outside the scope of this pathology text.

Slide 62 · Why β-catenin activation can change management

The pathway defines a biologically higher-risk group.

An exon 3 CTNNB1 mutation is particularly concerning.

Robbins recommends resection of β-catenin–activated tumors.

Risk assessment must not depend on size alone.

Slide 63 · Lower-risk conservative pathway in the source

Small adenoma

No β-catenin activation

Stop relevant hormone/steroid exposure

Close follow-up may be sufficient

This pathway is conditional; The textbook does not prescribe exact follow-up intervals.

Slide 64 · Exposure cessation has a specific role

Cessation of oral contraceptives or anabolic steroids may accompany surveillance.

This approach is discussed for smaller tumors without β-catenin activation.

It should not override resection indications for higher-risk lesions.

The source does not specify a universal regression rate after cessation.

Slide 65 · Management considerations: An editable decision map

Hepatocellular adenoma

Male sex / β-catenin activation / ≥5 cm

Resection recommended

Smaller and no β-catenin activation

Close follow-up + stop relevant exposure may suffice

Slide 66 · Teaching case: Incidental adenoma

Hypothetical teaching scenario

A young woman has a small incidental adenoma. Tumor hepatocytes show steatosis and loss of LFABP, with preserved staining in surrounding liver.

Which molecular subtype best explains the pathology?

Interpretation

HNF1α-inactivated adenoma: HNF1A loss is linked to steatosis and tumor-cell LFABP loss.

Slide 67 · Teaching case: Inflammatory pattern

Hypothetical teaching scenario

A hepatocellular lesion shows sinusoidal dilatation, fibrous septa and ductular reaction. Neoplastic hepatocytes strongly express CRP.

What pathway explains the immunophenotype?

Interpretation

The inflammatory adenoma pathway: Activating gp130 alteration with constitutive JAK–STAT signaling.

Slide 68 · Teaching case: High-risk genotype

Hypothetical teaching scenario

A hepatocellular adenoma shows architectural atypia and strong nuclear β-catenin staining. Sequencing identifies a CTNNB1 exon 3 mutation.

What risk concern predominates?

Interpretation

Malignant transformation to hepatocellular carcinoma; Exon 3 activation is a high-risk subtype.

Slide 69 · Teaching case: Sudden deterioration

Hypothetical teaching scenario

A patient with a known hepatic adenoma develops acute abdominal pain, and evaluation demonstrates intraperitoneal hemorrhage.

Which complication mandates urgent action?

Interpretation

Adenoma rupture with massive abdominal bleeding is a surgical emergency.

Slide 70 · Five discriminators worth retaining

Question

Most informative source-supported answer

Steatosis + LFABP loss?

HNF1α-inactivated subtype

CRP / SAA upregulation?

Inflammatory subtype

Nuclear β-catenin + atypia?

Wnt/β-catenin–activated subtype

GLI1 fusion + hemorrhage?

Sonic hedgehog subtype

Male / ≥5 cm / β-catenin activated?

Textbook resection recommendation

Slide 71 · Final synthesis: Diagnose biology, not only a mass

Identify adenoma by hepatocellular morphology and the absence of normal portal tracts.

Use morphology and pathway-linked immunostains to assign molecular phenotype.

Consider hemorrhage and malignant transformation as separate consequences.

Integrate sex, size and β-catenin status when discussing resection risk.

Slide 72 · Reference and interpretation notes

Robbins, Cotran & Kumar: Pathologic Basis of Disease. 11th ed. (2026). Chapter 18: Liver and Gallbladder. Hepatocellular Adenoma, pp. 788–790.

Molecular frequencies and treatment statements reproduce the supplied chapter extract.

Simplified histology and immunostain drawings are original editable schematics, not specimen images.

Original printed-page PDF figures were not provided; direct figure-level verification was not possible.