Lichen planus

Lichen planus is an inflammatory disease that usually affects the skin, the mouth, or sometimes both.

Cause

The cause of lichen planus is not known, however there are cases of lichen planus-type rashes (known as lichenoid reactions) occurring as allergic reactions to medications for high blood pressure, heart disease and arthritis. These lichenoid reactions are referred to as lichenoid mucositis (of the mucosa) or dermatitis (of the skin). Lichen planus has been reported as a complication of chronic hepatitis C virus infection. It has been suggested that true lichen planus may respond to stress, where lesions may present on the mucosa or skin during times of stress in those with the disease. Lichen planus affects women more than men 3:2, and occurs most often in middle-aged adults. Lichen planus in children is rare.

Clinical features

The typical rash of lichen planus is well-described by the "5 P's": well-defined pruritic, planar, purple, polygonal papules. The commonly affected sites are near the wrist and the ankle. The rash tends to heal with prominent blue-black or brownish discoloration that persists for a long time. Besides the typical lesions, many morphological varieties of the rash may occur.

The presence of lesions is not constant and may wax and wane over time.

Inside the mouth, the disease may present in the (1) reticular form or in the (2) erosive form. (1) The reticular form is the more common presentation and manifests as white lacy streaks on the mucosa (known as Wickham striae) or as smaller papules (small raised area). The lesions tend to be bilateral and are asymptomatic. The lacy streaks may also be seen on other parts of the mouth, including the gingiva (gums), the tongue, palate and lips. (2) The erosive form presents with erythematous (red) areas that are ulcerated and uncomfortable. The erosion of the thin covering of cells (the epithelium) may occur in multiple areas of the mouth, or in one area, such as the gums. Wickham's striae may also be seen near these ulcerated areas.

Oral lesions tend to last far longer than skin LP lesions.

Lichen planus may also affect the genital mucosa - vulvovaginal-gingival lichen planus. It can resemble other skin conditions such as atopic dermatitis and psoriasis.

Differential Diagnosis

The clinical presentation of lichen planus may also resemble other conditions, including:

• Lichenoid drug reaction
• Discoid Lupus Erythematosus
• Chronic Ulcerative Stomatitis
• Pemphigus Vulgaris
• Benign Mucous Membrane Pemphigoid
• Oral leukoplakia
• Fricional keratosis

A biopsy is useful in identifying histological features that help differentiate lichen planus from these conditions.

Cure

Currently there is no cure for lichen planus but there are certain types of medicines used to reduce the effects of the inflammation. Lichen planus may go into a dormant state after treatment. There are also reports that lichen planus can flare up years after it is considered cured.

Medicines used to treat lichen planus include:

• Oral and topical steroids.
• Oral retinoids
• immunosuppressant medications
• hydroxychloroquine
• tacrolimus
• dapsone

Lichen planopilaris

Lichen Planopilaris is the specific name given to lichen planus on the scalp that may cause permanent, scarring alopecia. If left untreated the scarring will cause permanent hair loss. The Cicatricial Alopecia Research Foundation is a non-profit organization that provides support and resources for people with lichen planopilaris.

External links

• Links to photo of Lichen planopilaris (Cicatricial Alopecia Research Foundation)
• Links to pictures of Lichen planus (Hardin MD/Univ of Iowa)
• Lichen planus-like cutaneous lesions
• Lichen planus at DermNet NZ.
• Lichen Planus information, symptoms, variants, causes, diagnosis, and various treatment options. http://www.lichenplanus.com