What is oral lichen planus?
Oral lichen planus is lichen planus inside the mouth. Lichen planus is a chronic inflammatory skin condition.
Oral lichen planus
Who gets oral lichen planus?
Lichen planus affects about 1–2% of the adult population. It usually affects adults older than 45 years, with an average age at diagnosis of 50–60 years, although it may affect younger adults and children. It is more common in women than in men (1.4: 1). A history of lichen planus in family members is sometimes present.
Oral lichen planus affects 50% of patients with cutaneous lichen planus but may occur without skin lesions elsewhere.
What is the cause of oral lichen planus?
The precise cause of oral lichen planus is not fully understood. It involves cytotoxic CD8+ T lymphocytes and pro-inflammatory cytokines, which attack the oral epithelial cells — resulting in their death. The immune response is mediated by antigen-specific cells.
In most cases oral lichen planus is idiopathic, when the reaction is thought to be against autoantigens. In other cases, it may be precipitated by exogenous antigens described below.
- Drugs — this is called oral lichenoid drug reaction. It is most often due to gold therapy. Other medications include some antibiotics, nonsteroidal anti-inflammatory drugs, antimalarials, drugs used for treating hypertension and heart disease, and antiretroviral medicines. These drugs more commonly cause a lichenoid skin eruption, with the mouth being affected less often.
- Contact allergens in dental restorative materials (mercury, nickel, gold, resins, acrylates) or toothpaste, particularly spearmint. These may be identified by careful patch testing.
- Viral infection, particularly Hepatitis C
Oral lichenoid lesions are also part of the spectrum of chronic graft-versus-host disease that occurs after bone marrow transplantation.
Studies have demonstrated a lower serum vitamin D level in those with oral lichen planus compared to control groups.
Oral lichenoid lesions
What are the clinical features of oral lichen planus?
Oral lichen planus can affect any or all areas inside the mouth. It can be precipitated by psychosocial stress or by local mechanical trauma.
Oral lichen planus may present in the following forms, and is often of mixed types.
Reticular lichen planus
- Symmetrical white lace-like pattern on buccal mucosa (inner aspects of cheeks)
- There may be no symptoms or discomfort and soreness.
- May affect tongue or gums
- May ulcerate
Atrophic/erosive lichen planus
- Red lesions often with a whitish border
- My cause erosions (superficial ulceration)
- Most often affects the gums (gingiva) and lips
- Can be very painful
- May be associated with erosive lichen planus affecting genital sites
Plaque type oral lichen planus
- Usually seen in smokers
- Confluent white patches similar to oral keratoses
Oral lichen planus
How is the diagnosis of oral lichen planus made?
The diagnosis of oral lichen planus is often made by its clinical appearance. Tissue biopsy may be helpful, when characteristic features of lichen planus may be observed. Biopsy can help exclude other oral conditions with lichenoid reaction, such as drug-induced lichenoid reaction, oral lupus erythematosus, or a contact lichenoid reaction.
Under the microscope, the pathologist may observe a characteristic lichenoid reaction. Direct immunofluorescence may reveal positive staining for fibrinogen, immunoglobulins and complement.
Biopsy is often performed to rule out oral cancer.
What are the complications of oral lichen planus?
Oral lichen planus can be very painful and ulceration may lead to scarring. Sometimes eating is so uncomfortable that affected person is unable to maintain adequate nutrition.
Lichen planus, particularly the erosive form, may rarely lead to oral cancer (squamous cell carcinoma). Persistent ulcers and enlarging nodules should undergo biopsy.
Oral lichen planus and squamous cell carcinoma
Management of oral lichen planus
It is important to identify and remove or avoid any potential agent that might have caused a lichenoid reaction, such as drugs that have been started in recent months and contact allergens identified by patch testing.
Most people get satisfactory control of symptoms with the following measures.
- Meticulous oral hygiene: brushing teeth and gums, regular visits to dentist, once-weekly mouthwash with diluted chlorhexidine or benzydamine
- If standard toothpaste irritates, try products that do not contain sodium lauryl sulphate
- Vitamin D supplementation (if indicated)
- Stop smoking
- Topical chamomile gel
- Topical anaesthetic gel
- Topical retinoid, for example tretinoin or isotretinoin gel
- Topical steroids as drops, pastes, gels or sprays, for example, triamcinolone in an emollient dental paste, fluticasone nasal preparations, and clobetasol propionate in various forms. Topical steroids can be delivered to oral lichen planus affecting the gums within a polyvinyl siloxane medication tray, held in place for a couple of hours.
- Steroid injections (intralesional triamcinolone)
- Mouth rinse containing dexamethasone (1 mg dissolved in 10 ml warm water) or a calcineurin inhibitor (ciclosporin or tacrolimus); this is spat out afterwards.
In severe cases systemic corticosteroids may be used.
Other possible therapeutic agents may include:
- Systemic retinoids (acitretin or isotretinoin)
- Griseofulvin
- Hydroxychloroquine
- Azathioprine
- Cyclophosphamide
- Methotrexate
- Mycophenolate
- Dapsone
- Metronidazole
- Oral roflumilast
- Thalidomide
- Low molecular weight heparin.
Targeted molecular medicines are under investigation for the treatment or recalcitrant disease, with apremilast reported effective in a few patients.
What is the outcome of lichen planus?
The prognosis for oral lichen planus is uncertain. It can clear up within a few months or persist (with or without treatment) for decades. There are often periods of remission and relapse.