Leukoplakia and Erythroplakia

Slide 1 · Leukoplakia and Erythroplakia

Oral precancerous lesions • clinical morphology and histologic significance

Clinical description → epithelial histology → cancer risk

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning objectives

Define leukoplakia, erythroplakia, and mixed red–white lesions using their clinical features.

Explain exclusion-based diagnosis, anatomic distribution, and typical associations.

Interpret the range of epithelial abnormalities and their implications for biopsy.

Diagnostic principle

Clinical appearance ≠ histologic diagnosis

Slide 3 · The oral precancer spectrum

Clinical lesion

White, red, or mixed

Histologic assessment

Keratosis to atypia

Disease significance

Potential cancer precursor

Clinical reasoning

The surface appearance raises suspicion; Tissue examination resolves the epithelial diagnosis.

Slide 4 · A clinical label is not a tissue diagnosis

Clinical description

Leukoplakia: An otherwise unexplained non-scrapable white plaque.

Erythroplakia: A red, often velvety and slightly depressed area.

Interpretation

Biopsy may reveal an orderly, keratotic epithelium.

Alternatively, it may show dysplasia, carcinoma in situ, or invasion.

Slide 5 · Leukoplakia: Definition in practice

White plaque

Seen in oral cavity

Cannot scrape off

Adherent to surface

No other cause

Alternative disease excluded

Clinical reasoning

Robbins quotes the WHO definition as an exclusion-based clinical category.

Slide 6 · “No apparent reason” is essential

Not every oral white patch is leukoplakia.

An obvious irritant-associated plaque is excluded from the clinical category.

Recognizable entities such as lichen planus or candidiasis are also excluded.

Diagnostic principle

The definition requires ruling out explanations, not simply observing whiteness.

Slide 7 · Scrapability is a useful first discriminator

Clinical description

Non-scrapable: Compatible with the clinical morphology of leukoplakia.

Persistence after gentle attempted removal warrants further assessment.

Interpretation

Scrapable white material suggests another process; Candidiasis is a major example.

Scrapability alone cannot assign a complete pathologic diagnosis.

Slide 8 · White plaques: The clinical exclusion problem

Presentation

Clue

Interpretive point

Leukoplakia

White, non-scrapable

Diagnosis after exclusion

Candidiasis

White oral fungal disease

Not leukoplakia when identifiable

Lichen planus

Reticulate, lacelike keratosis

A distinct recognized disorder

Irritation-related plaque

Obvious mechanical association

Excluded when attributable

Interpretation

A visible white lesion must be placed in its clinical context.

Slide 9 · Candidiasis is not leukoplakia

Oral candidiasis is a defined infection of the mucosa.

The Robbins leukoplakia definition specifically excludes candidiasis.

A definitive clinical interpretation depends on recognizing the underlying process.

Diagnostic principle

White color is not the deciding criterion.

Slide 10 · Oral lichen planus is a distinct mimic

Lichen planus may cause reticulate, lacelike white keratotic lesions.

Its recognizable pattern differs from an otherwise unexplained plaque.

If the diagnosis is lichen planus, the lesion is not classified as leukoplakia.

Diagnostic principle

The clinical morphology can be white without satisfying leukoplakia.

Slide 11 · Hairy leukoplakia: Similar name, different lesion

Clinical description

EBV-related lesion classically affecting lateral tongue.

Fluffy or hairy, hyperkeratotic and non-scrapable in immunocompromised people.

Interpretation

Etiology and histology are distinctive: EBV-related ballooning changes.

Do not group it automatically with idiopathic potentially malignant leukoplakia.

Slide 12 · Practical classification of a white lesion

See white patch

Record location, surface

Check features

Scrapability and cause

Exclude disease

Infection, lichen planus, irritation

Assess tissue

Histology when indicated

Clinical reasoning

This is a reasoning schematic, not a substitute for a clinical protocol.

Slide 13 · Frequency of oral leukoplakia

~3%

Approximate worldwide population prevalence as quoted by Robbins

This is prevalence of the clinical lesion.

It is not the percentage that will transform into cancer.

Slide 14 · Premalignant lesions among leukoplakias

5–25%

Share described as premalignant in the Robbins text

This range concerns the proportion of lesions classified as premalignant.

It must not be relabeled as a follow-up malignant transformation rate.

Histologic evaluation is critical because risk is heterogeneous.

Slide 15 · Typical age and sex distribution

40–70 years

Usual age range; Approximately 2:1 male predominance

The lesions may also be observed at other adult ages.

These patterns characterize the reported population, not a diagnostic rule.

Slide 16 · Tobacco exposure: Different forms

Exposure named

Examples

Interpretation

Smoked tobacco

Cigarettes

Common antecedent

Smoked tobacco

Pipes

Common antecedent

Smoked tobacco

Cigars

Common antecedent

Smokeless tobacco

Certain forms

Common antecedent

Interpretation

The source characterizes the origin of these lesions as multifactorial.

Slide 17 · Why tobacco is relevant

Exposure history

Identify antecedents

Clinical plaque

White / red / mixed

Histologic check

Look for atypical epithelium

Clinical reasoning

Association does not mean every lesion has one identifiable cause.

Slide 18 · Multifactorial origin: Avoid oversimplification

Both lesion types as multifactorial.

Tobacco is common but not a universal antecedent.

The clinical appearance alone does not prove a particular causative exposure.

Diagnostic principle

A complete assessment avoids attributing every white plaque to smoking.

Slide 19 · Favored oral sites for leukoplakia

Site

Clinical implication

Buccal mucosa

Inspection of the cheek lining

Floor of mouth

Attention to mucosa beneath tongue

Ventral tongue

Inspect the inferior tongue surface

Palate

Evaluate palatal mucosa

Gingiva

Examine attached oral mucosa

Interpretation

The lesion may also occur elsewhere in the oral cavity.

Slide 20 · White patches may be solitary or multiple

The number of plaques varies across presentations.

Single or multiple lesions both fit the description.

The distribution should be recorded rather than assumed from the name.

Oral mucosal surface (schematic)

Non-scrapable white plaque

Slide 21 · Sharp demarcation can be a useful clue

Leukoplakia often has clearly delimited margins.

The border helps define the extent of the visible plaque.

A sharply outlined lesion is not necessarily histologically benign.

Oral mucosal surface (schematic)

Non-scrapable white plaque

Slide 22 · A smooth white plaque is still leukoplakia

Some plaques are only slightly thickened.

The surface may be clinically smooth rather than irregular.

Thickness does not by itself resolve the presence of dysplasia.

Oral mucosal surface (schematic)

Non-scrapable white plaque

Slide 23 · Wrinkled and fissured white plaques

A leukoplakic plaque may show wrinkling or surface fissures.

These are variations within its reported gross appearance.

Clinical appearance alone cannot assign epithelial grade.

Oral mucosal surface (schematic)

Non-scrapable white plaque

Slide 24 · Raised, corrugated, and verrucous plaques

Some leukoplakias are elevated above adjacent mucosa.

A corrugated or verrucous surface is a recognized morphology.

Biopsy is needed to determine the epithelial pathology beneath the surface.

Oral mucosal surface (schematic)

Non-scrapable white plaque

Slide 25 · Leukoplakia is morphologically heterogeneous

Pattern

Surface or contour

What is not established

Smooth

Slightly thickened

Histologic grade

Wrinkled

Folds or fissures

Presence of carcinoma

Verrucous

Raised, corrugated

Invasive status

Multiple

Separated white plaques

Whether all foci are equivalent

Interpretation

External appearance cannot replace epithelial assessment.

Slide 26 · Erythroplakia: A red velvety area

Less common than leukoplakia in the Robbins description.

Red, velvety appearance, sometimes with erosion.

The red lesion has a much greater association with serious epithelial atypia.

Oral mucosal surface (schematic)

Flat / slightly depressed red area

Slide 27 · Erythroplakia may be flat or depressed

The lesion commonly remains level with adjacent oral mucosa.

It may also be slightly below the surrounding surface.

A red, non-elevated lesion can still conceal high-grade pathology.

Oral mucosal surface (schematic)

Flat / slightly depressed red area

Slide 28 · Surface erosion in erythroplakia

An eroded component may accompany the red lesion.

Erosion is part of the gross description, not proof of invasion.

The mucosa should be sampled rather than judged by color alone.

Oral mucosal surface (schematic)

Flat / slightly depressed red area

Slide 29 · Why erythroplakia appears red

A prominent subepithelial inflammatory reaction may be present.

Vascular dilatation increases the visible redness.

Epithelial atypia can accompany this striking vascular background.

Schematic epithelium • not a micrograph

Dilated subepithelial vessels

Slide 30 · Speckled erythroplakia mixes white and red

Mixed lesions show features of both lesion categories.

Robbins calls these intermediate forms “speckled erythroplakia.”

A single field can therefore contain contrasting surface appearances.

Oral mucosal surface (schematic)

Intermixed red and white areas

Slide 31 · Clinical red–white spectrum

Clinical description

Predominantly white: Leukoplakia.

May be smooth, fissured, or raised.

Interpretation

Predominantly red: Erythroplakia.

Speckled forms display intermixed red and white.

Slide 32 · Leukoplakia vs erythroplakia

Dimension

Leukoplakia

Erythroplakia

Color

White

Red

Typical texture

Smooth to verrucous

Velvety; May be eroded

Profile

More common

Less common

Histology

Broad spectrum

Usually markedly atypical

Implication

Biopsy to establish grade

Especially high concern

Interpretation

These are clinical tendencies, not absolute diagnostic criteria.

Slide 33 · Normal oral stratified epithelium: Orientation

A layered squamous epithelium matures toward its surface.

Its basement membrane separates epithelium from underlying tissue.

The orderly reference pattern is necessary to understand dysplasia.

Schematic epithelium • not a micrograph

Stratification and maturation

Slide 34 · Hyperkeratosis: A surface-layer abnormality

Increased keratin as one end of the leukoplakia spectrum.

The surface material contributes to the clinically white plaque.

Keratosis may overlie an otherwise orderly epithelium.

Schematic epithelium • not a micrograph

Thickened surface keratin layer

Slide 35 · Acanthosis: A thickened squamous epithelium

Acanthosis represents expansion of the epithelial thickness.

It may coexist with overlying hyperkeratosis.

An acanthotic epithelium can still show orderly maturation.

Schematic epithelium • not a micrograph

Expanded squamous epithelial thickness

Slide 36 · Orderly maturation is distinct from atypia

Some leukoplakias show thick but organized mucosal epithelium.

The distinction rests on the cellular pattern, not simply its thickness.

This is one benign end of the microscopic range.

Schematic epithelium • not a micrograph

Stratification and maturation

Slide 37 · Dysplasia disrupts epithelial organization

Markedly dysplastic leukoplakias depart from orderly squamous maturation.

Atypical morphology is assessed in an adequate tissue sample.

Gross thickness and white color alone cannot determine this finding.

Schematic epithelium • not a micrograph

Loss of orderly maturation

Slide 38 · Carcinoma in situ: Severe intraepithelial change

Leukoplakia sometimes merging into carcinoma in situ.

The atypical cells remain on the epithelial side of the basement membrane.

Intraepithelial carcinoma must not be confused with stromal invasion.

Schematic epithelium • not a micrograph

Basement membrane intact

Slide 39 · Leukoplakia: The histologic breadth

Keratin thickening

Hyperkeratosis

Epithelial growth

Acanthosis, orderly

Atypia

Dysplasia

In situ disease

Carcinoma in situ

Clinical reasoning

Illustrates the spectrum of possible findings, not obligatory progression.

Slide 40 · Erythroplakia rarely matures normally

Orderly epithelial maturation is unusual in erythroplakia.

Most lesions show major epithelial abnormalities at evaluation.

This difference underlies its greater clinical concern.

Schematic epithelium • not a micrograph

Loss of orderly maturation

Slide 41 · Histology of erythroplakia

~90%

Severe dysplasia, carcinoma in situ, or minimally invasive carcinoma

This as a proportion of lesions at histologic evaluation.

It is NOT a prospective risk of later malignant transformation.

It emphasizes the need for tissue confirmation.

Slide 42 · Prevalent carcinoma ≠ future transformation

Clinical description

At biopsy: A lesion can already contain severe dysplasia, carcinoma in situ, or invasion.

The ~90% erythroplakia statistic concerns findings already present.

Interpretation

Follow-up risk: Later development of invasive carcinoma after an initial diagnosis.

Robbins does not supply a numerical longitudinal transformation rate in this passage.

Slide 43 · Carcinoma in situ versus invasion

Carcinoma in situ is confined to the epithelium.

Invasion means malignant epithelial cells have crossed the basement membrane.

Robbins explicitly includes minimally invasive carcinoma within the erythroplakia findings.

Schematic epithelium • not a micrograph

Basement membrane intact

Slide 44 · The two axes of clinical assessment

Clinical appearance

White / red / speckled

Tissue examination

Keratosis / dysplasia / carcinoma

Clinical decision

Interpret grade and invasion

Clinical reasoning

Keep the clinical descriptor and the pathologic conclusion separate.

Slide 45 · Why all unexplained leukoplakias matter

Robbins advises considering every leukoplakia precancerous until histologic assessment.

Only tissue assessment separates benign reactive morphology from dysplasia or carcinoma.

A clinically unremarkable white surface can be histologically important.

Diagnostic principle

The wording describes an initial safety stance, not certainty that every plaque is dysplastic.

Slide 46 · Biopsy resolves the diagnostic uncertainty

Recognize lesion

Describe surface and sites

Exclude known cause

Irritant and defined diseases

Obtain histology

Evaluate epithelial pattern

Integrate findings

Grade and invasion

Clinical reasoning

Conceptual workflow derived, not a patient-specific treatment guideline.

Slide 47 · Clinical pattern cannot grade dysplasia

White plaques range from orderly hyperkeratotic mucosa to carcinoma in situ.

Red lesions tend to show marked atypia but still require histologic confirmation.

Do not assign a microscopic grade from a clinical photograph alone.

Diagnostic principle

Visible color and microscopic severity are different dimensions.

Slide 48 · A pathology report answers distinct questions

Question

Pathologic observation

Is the epithelium thickened?

Hyperkeratosis and acanthosis

Is maturation preserved?

Orderly versus dysplastic change

Is carcinoma in situ present?

Marked intraepithelial atypia

Is invasion present?

Relation to basement membrane

Interpretation

This is a conceptual checklist, not a mandated reporting dataset.

Slide 49 · Interpret a mixed lesion with caution

Red and white zones can coexist within a lesion.

The combined clinical label does not establish an identical microscopic pattern throughout.

Histologic assessment remains necessary for the clinically suspicious region.

Diagnostic principle

Color differences identify areas to evaluate, but do not prove grade.

Slide 50 · Case 1 • A removable white coating

Hypothetical clinical scenario

A patient has white oral material that is readily wiped away during examination.

Does the lesion meet the Robbins definition of leukoplakia?

Which defining feature fails?

DISCUSSION

No. Leukoplakia requires a non-scrapable plaque; Investigate a defined alternative such as candidiasis.

Slide 51 · Case 2 • Lacelike white striae

Hypothetical clinical scenario

A patient has bilateral reticulate, lacelike keratotic changes of the oral mucosa.

Which recognized entity is specifically excluded?

Why is a white appearance insufficient?

DISCUSSION

A typical lichen-planus pattern does not qualify as otherwise unexplained leukoplakia.

Slide 52 · Case 3 • Lateral tongue with EBV pattern

Hypothetical clinical scenario

An immunocompromised patient shows confluent, fluffy, hyperkeratotic patches on the lateral tongue.

Which similarly named disorder belongs in the differential?

What etiologic association distinguishes it?

DISCUSSION

Hairy leukoplakia: An EBV-related disorder, rather than idiopathic potentially malignant leukoplakia.

Slide 53 · Case 4 • A smooth persistent white plaque

Hypothetical clinical scenario

An otherwise unexplained, smooth, non-scrapable white patch remains visible on the buccal mucosa.

Is its smoothness reassuring enough to exclude dysplasia?

What determines epithelial pathology?

DISCUSSION

No. Even smooth leukoplakia requires appropriate tissue assessment to distinguish keratosis from atypia.

Slide 54 · Case 5 • A red velvety gingival plaque

Hypothetical clinical scenario

A sharply visible red, flat, velvety plaque involves gingival mucosa and is not a recognized inflammatory disorder.

Which clinical category is most concerning?

What broad set of epithelial diagnoses is common?

DISCUSSION

Suspicious for erythroplakia; Severe dysplasia, in situ carcinoma or minimal invasion in ~90% of biopsied lesions.

Slide 55 · Case 6 • One lesion, two colors

Hypothetical clinical scenario

An oral plaque contains contiguous red and white areas with a heterogeneous surface.

What term describes the mixed appearance?

Does color alone tell whether the lesion invades?

DISCUSSION

Speckled erythroplakia; Histology, not color, determines dysplasia, carcinoma in situ, or invasion.

Slide 56 · Case 7 • Histology without disorderly maturation

Hypothetical clinical scenario

A biopsy shows hyperkeratosis over a thickened epithelium that still matures in an orderly manner.

Which end of the Robbins microscopic range is illustrated?

Does the clinical label require severe dysplasia?

DISCUSSION

This fits the hyperkeratotic/acanthotic orderly end of the leukoplakia spectrum; Severe dysplasia is not obligatory.

Slide 57 · Case 8 • Marked atypia but intact interface

Hypothetical clinical scenario

Biopsy of a suspicious oral plaque shows marked full-thickness epithelial atypia without stromal infiltration.

Why is the basement membrane important?

Which epithelial diagnosis is conceptually supported?

DISCUSSION

Carcinoma in situ: A high-grade intraepithelial process, differentiated from invasion by confinement above the basement membrane.

Slide 58 · Synthesis: Appearance → tissue → meaning

Clinical observation

Possible histology

Teaching implication

Non-scrapable white

Hyperkeratosis to in situ disease

Do not assume benignity

Red, velvety, flat

Usually severe atypia or carcinoma

High-priority histology

Mixed red–white

Variable epithelial abnormality

Describe heterogeneous surface

Recognized mimic

Different specific disorder

Exclude before leukoplakia label

Interpretation

Lesion labels are starting points in diagnosis.

Slide 59 · Five principles to retain

Leukoplakia is an exclusion-based diagnosis of a non-scrapable white plaque.

Erythroplakia is less common and substantially more ominous.

Both may be associated with tobacco; Neither is explained by one factor alone.

White lesions range from orderly keratosis to carcinoma in situ.

Erythroplakia commonly harbors severe atypia or early carcinoma.

Diagnostic principle

Do not confuse initial histology proportions with longitudinal transformation risk.

Slide 60 · References and source boundaries

Robbins, Cotran & Kumar. Pathologic Basis of Disease. 11th ed. 2026. Chapter 16, Head and Neck, pp. 667–668.

Primary text: “Leukoplakia and Erythroplakia” and the displaced morphology continuation immediately preceding the squamous-cell carcinoma discussion.

Earlier oral-cavity sections used only to distinguish candidiasis, lichen planus, and EBV-related hairy leukoplakia.

Clinical scenarios and drawings in this lecture are instructional constructions, not patient records, specimens, or published study figures.