Oral leukoplakia
OL; "white patch of the oral mucosa"; (with red component, "speckled erythroleukoplakia"); proliferative verrucous leukoplakia (PVL) — distinctive aggressive variant
Oral leukoplakia is defined by the World Health Organization as a "predominantly white plaque of questionable risk having excluded other known diseases or disorders that carry no increased risk for cancer". It is therefore a clinical diagnosis of exclusion — only after frictional keratoses, oral candidiasis, lichen planus, lichenoid drug reaction, lupus, leukoedema, white sponge nevus and the other "removable / definable" white oral patches have been excluded does the term "leukoplakia" apply. Globally, oral leukoplakia affects ~2% of adults; approximately 1% per year (range varies widely) transform to oral squamous cell carcinoma — making it the principal pre-malignant entity of the oral cavity and the leading reason for oral medicine surveillance. Risk factors for transformation include red component (erythroleukoplakia), non-homogeneous / nodular surface, location (lateral tongue, floor of mouth), large size (>200 mm²), high-grade dysplasia on biopsy, female sex, non-smoker (paradoxical, suggesting more aggressive intrinsic biology), and the proliferative verrucous leukoplakia (PVL) variant — a clinically distinct multifocal verrucous condition with extraordinarily high (~70%) lifetime malignant transformation rate.
Clinical features
- White plaque of oral mucosa that cannot be wiped off and cannot be characterised as a specific other disease.
- Sites — buccal mucosa (commonest), gingiva, alveolar ridge, lateral and ventral tongue, floor of mouth, palate, lip vermilion.
- Subtypes:
- Homogeneous leukoplakia — uniform white plaque, smooth or wrinkled; lower transformation risk.
- Non-homogeneous leukoplakia — variegated white-red, nodular, verrucous or speckled; higher transformation risk.
- Erythroleukoplakia / "speckled leukoplakia" — combined white and red areas; high transformation risk (similar to erythroplakia).
- Proliferative verrucous leukoplakia (PVL) — multifocal, persistent, progressive verrucous white plaques affecting multiple oral subsites; predominantly older women, often non-smokers; ~70% lifetime malignant transformation.
- Risk factors — tobacco (smoked, smokeless, paan, betel quid), alcohol, HPV co-infection (particularly HPV-16), poor oral hygiene, chronic irritation, immunosuppression.
Risk of malignant transformation
- Overall approximately 1% per year (range varies widely) malignant transformation to oral squamous cell carcinoma; lifetime ~5–15% for typical leukoplakia, much higher for PVL.
- Risk factors for transformation:
- Red component (erythroleukoplakia / speckled).
- Non-homogeneous / nodular / verrucous surface.
- High-risk site — lateral / ventral tongue, floor of mouth (the "horseshoe" of high-risk anatomical sites).
- Large size (>200 mm² or >5 mm).
- High-grade dysplasia on biopsy histology.
- Female sex.
- Non-smokers (paradoxical; suggests more aggressive intrinsic biology — leukoplakia in non-smokers carries higher transformation risk than smoker-associated leukoplakia).
- HPV-16 positivity.
- PVL phenotype.
- Long duration.
Diagnosis & biopsy
- Step 1 — exclude removable / definable conditions:
- Frictional keratosis (cheek-biting, sharp tooth) — resolves on cessation of trauma.
- Oral candidiasis — KOH / culture; resolves with antifungal.
- Oral lichen planus — bilateral, symmetrical, Wickham striae; biopsy if doubt.
- Lichenoid drug eruption — culprit drug.
- Discoid lupus erythematosus.
- Leukoedema, white sponge nevus, hereditary benign intraepithelial dyskeratosis.
- Hairy leukoplakia (lateral tongue, EBV in HIV).
- Smoker's keratosis (palatal).
- Chemical / heat burn.
- If white plaque persists despite removal of presumed cause, label as oral leukoplakia.
- Biopsy is mandatory for any oral leukoplakia:
- Multiple incisional biopsies if extensive, particularly from any nodular / red / atypical area.
- Excisional biopsy for small lesions.
- Histology grades dysplasia (mild / moderate / severe / carcinoma in situ / invasive SCC) — the principal predictor of transformation risk.
- Refer to oral medicine / oral and maxillofacial surgery for any biopsy-confirmed leukoplakia.
Management
- Multidisciplinary care — oral medicine, oral and maxillofacial surgery, ENT, dental, dermatology; lifelong.
- Risk-factor modification:
- Smoking cessation — essential; partial regression of leukoplakia common.
- Reduce alcohol.
- Optimise oral hygiene; remove sources of mechanical trauma.
- Smokeless tobacco / betel quid cessation.
- Treatment of leukoplakia:
- Surgical excision is preferred for small / accessible / dysplastic lesions.
- CO₂ laser ablation, photodynamic therapy, cryotherapy — alternatives.
- Topical retinoids, topical 5-FU — modest efficacy.
- Oral retinoids — modest efficacy; significant toxicity.
- Treatment does not abolish transformation risk; surveillance must continue.
- Surveillance:
- 3–6-monthly clinical follow-up by oral medicine.
- Re-biopsy any change.
- Lifelong; transformation may occur years to decades after initial diagnosis.
- PVL — quarterly surveillance with very low threshold for re-biopsy.
- If transformation to invasive SCC — refer to head and neck cancer MDT for staging and definitive management (per UK head/neck cancer pathways).
References
- Warnakulasuriya S et al. Oral potentially malignant disorders — consensus report from an international seminar on nomenclature and classification. Oral Dis; 2021.
- Speight PM et al. Oral cancer risk in oral leukoplakia. Oral Oncol; 2018.
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