Oral lichen planus

What is oral lichen planus?

Oral lichen planus is lichen planus inside the mouth.

Lichen planus is a chronic inflammatory skin condition affecting about 1-2% of the adult population. It usually affects adults older than 45 years, although it may affect younger adults and children. It is more common in women than in men (1.4: 1).

Oral lichen planus affects 50% of patients with skin lichen planus but may occur without skin lesions elsewhere. All areas inside the mouth can be affected. There may be no symptoms but it can cause discomfort, lumps and ulcers.

Clinical features of oral lichen planus

Oral lichen planus may present in the following forms, and is often of mixed types.

Oral lichen planus

Plaque lichen planus	Reticular lichen planus	Erosive lichen planus	Ulcerative lichen planus
Lichenoid reaction to amalgam	Graft versus host disease	Lichenoid drug reaction	Alveolar cancer
Images 1–7 supplied by Dr David Hay, Auckland

What is the cause of oral lichen planus?

The precise cause of oral lichen planus is unknown. It appears to be an autoimmune disease in which cells called CD8+ T lymphocytes, and chemical mediators such as the cytokine TNF, attack the oral epithelial cells resulting in their death.

In most cases the disease appears unexpectedly and is called idiopathic oral lichen planus. In other cases it may be precipitated by the following:

• Drugs i.e., oral lichenoid drug reaction. This is most often due to gold therapy. Other medications include some antibiotics, non steroidal anti-inflammatory drugs, drugs used for treating hypertension, heart disease and high lipids. These drugs more commonly cause a skin eruption with the mouth being affected less often.
• Contact allergens in dental restorative materials (mercury) or toothpastes, particularly spearmint. These may be identified by careful patch testing
• Mechanical trauma
• 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.

How is the diagnosis of oral lichen planus made?

The diagnosis of oral lichen planus is often made by its clinical appearance. However tissue biopsy may be helpful, when characteristic features of lichen planus may be observed.

Under the microsope, 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.

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 may rarely lead to oral cancer (squamous cell carcinoma). Persistent ulcers and enlarging nodules should undergo biopsy.

Management of oral lichen planus

It is important to identify and remove 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
• If standard toothpaste irritates, try products that do not contain sodium lauryl sulfate
• Stop smoking
• Topical steroids as drops, pastes, gels or sprays. Triamcinolone in an emollient dental paste or fluticasone nasal preparations are often prescribed.
• Steroid injections (intralesional triamcinolone)
• Mouth rinse containing the calcineurin inhibitors: ciclosporin or tacrolimus

In severe cases systemic corticosteroids may be used.

Other possible therapeutic agents may include:

• Thalidomide
• Systemic retinoids (acitretin or isotretinoin)
• Griseofulvin
• Azathioprine
• Cyclophosphamide
• Dapsone
• Metronidazole
• Low molecular weight heparin