Oral Lichenoid Reaction

Oral lichenoid reaction is a mucosal lesion that looks like oral lichen planus but has an identifiable trigger, most often a drug or a contact allergen from a dental restoration.

It is usually unilateral or sits next to the offending material, whereas classic lichen planus tends to be bilateral and symmetrical. The buccal mucosa and lateral tongue are the commonest sites, and erosive or ulcerated forms are frequent.

Pathophysiology. A T-cell mediated hypersensitivity develops against an antigen in the epithelium, producing basal cell damage, a band like or perivascular lymphocytic infiltrate and cicatricial change in long standing disease.

Triggers: dental amalgam, composite resins, gold, nickel, cobalt and palladium, cinnamon and other flavourings, and drugs including non-steroidal anti-inflammatory drugs, ACE inhibitors, beta blockers, thiazides, methyldopa, sulphonylureas, allopurinol, antimalarials, penicillamine and imatinib.

Graft-versus-host disease and some infections can produce the same picture.

White striae, papules, plaques, erythema or erosions, often with burning or soreness on hot, spicy or acidic food. Lesions are commonly one sided or lie in direct contact with an amalgam or other restoration, and they may involve the gingiva, palate or lip.

Ask for the drug history with start dates, because onset is typically weeks to months after a new drug or dose, and for dental work and new oral hygiene products. Skin, nails, scalp and genital examination helps separate a reaction from idiopathic lichen planus.

Dysplastic or malignant change is more frequent than in unselected mucosal disease, so a lesion that is red, speckled, indurated, ulcerated for more than 3 weeks or growing needs prompt biopsy and urgent specialist review.

• Incisional biopsy from the edge of an erosion or from the white area, with histology: a lichenoid band with deeper and more perivascular inflammation, eosinophils and plasma cells, which favours a reaction. Features are not fully discriminating, so clinical correlation decides.
• Direct immunofluorescence on perilesional tissue if bullous or ulcerated disease raises the question of pemphigoid or pemphigus.
• Patch testing to a dental series when a restoration lies against the lesion. A positive result predicts improvement after replacement.
• Drug timeline and, with the prescriber, withdrawal or substitution of the drug with the prescriber.
• Full blood count, ferritin, vitamin B12, folate, glucose or HbA1c and hepatitis C serology if idiopathic lichen planus is considered.
• Swab for Candida where erythema or angular cheilitis suggests superinfection.

Differential diagnosis.

• Oral lichen planus
• Leukoplakia with or without dysplasia
• Oral squamous cell carcinoma
• Chronic graft-versus-host disease
• Discoid lupus erythematosus
• Mucous membrane pemphigoid or pemphigus vulgaris
• Chronic ulcerative stomatitis
• Candidiasis

• Remove the cause first. Stop or substitute the suspected drug with the prescriber, and replace the contact restoration only when patch testing is positive or the lesion lies directly against it. Resolution takes weeks to months.
• Meticulous oral hygiene, removal of plaque and calculus, and avoidance of cinnamon and strongly flavoured products and of alcohol containing mouthwash.
• Topical corticosteroid for symptomatic erosive disease: clobetasol propionate 0.05% gel or ointment applied thinly with a finger or custom tray 2 to 3 times daily for 2 to 4 weeks, then reduced to once daily or on alternate days. Alternatively, betamethasone sodium phosphate 0.5 mg soluble tablet dissolved in 10 mL of water, rinsed for 2 minutes and spat out, up to four times daily, for up to 2 to 4 weeks.
• Candida prophylaxis during steroid use: miconazole oral gel 20 mg/g, 2.5 mL four times daily for 7 days when candidiasis develops, held on the lesion. Miconazole raises the INR with warfarin, so avoid it or check the INR within 3 to 5 days, and it interacts with simvastatin and sulphonylureas.
• Steroid sparing option in specialist hands: tacrolimus 0.1% ointment twice daily for erosive disease unresponsive to steroid. Warn about the boxed warning on long term use and lymphoma and skin malignancy, avoid in pregnancy, and avoid sun exposure to treated skin.
• Severe, multifocal disease: prednisolone 0.5 mg/kg (maximum 40 mg) orally each morning for 5 to 7 days, stopped without taper if the course is under 2 weeks, with glucose and blood pressure checks.
• Dysplasia on biopsy: excision or laser ablation with continued surveillance.

Special groups. Pregnancy: avoid tacrolimus and systemic immunosuppressants. Graft-versus-host disease needs transplant physician review and systemic therapy directed by the haematology team.

Monitoring. Review at 4 to 6 weeks for response, then every 6 to 12 months for life because of malignant potential. Repeat biopsy for any change in colour, texture, ulceration or induration.

Referral and escalation. Refer to oral medicine for all cases, and urgently within 2 weeks when malignancy is suspected, ulceration persists beyond 3 weeks, or the lesion fails to improve after the cause has been removed.