Symptoms and signs

• Recurrent rash that is small, violaceous, flat-topped, many-sided (polygonal) bumps
• The typical rash of lichen planus is well-described by the "4 P's": pruritic, planar, purple, polygonal papules
• The rash tends to heal with prominent blue-black or brownish discoloration that persists for a long time
• Small, pale raised areas or bumps that form a lacy network on the tongue or inside the cheeks
• Shiny, red, slightly raised patches on the tongue or cheeks
• Red, open sores in the mouth
• Pain, tenderness, burning or itching in the mouth
• Dry mouth
• A metallic taste or a blunted taste sensation
• Grooving, splitting, thinning or nail loss when involving the nails
• Redness, irritation, hair thinning and hair loss when involving the scalp

 Causes of lichen planus

The cause of lichen planus is not known. It is not contagious and does not involve any known pathogen.

Some lichen planus-type rashes (known as lichenoid reactions) occur as allergic reactions to medications for high blood pressure, heart disease and arthritis.

As a complication of chronic hepatitis C virus infection and can be a sign of chronic graft-versus-host disease of the skin.

Lichen planus appears to be associated with hypothyroidism.

Complications

People with long-term lesions of the mucous membranes are at greater risk of squamous cell carcinoma — a form of skin cancer.

It's also important to stop any tobacco use because tobacco raises your risk of squamous cell carcinoma.

Tests and diagnosis

It's also important to stop any tobacco use because tobacco raises your risk of squamous cell carcinoma.

A punch biopsy extends about 1/4 inch (6 millimeters) deep.

Treatment

• Antihistamines- Cetrizine, loratidine, diphenhyramine, etc
• Cream or ointment applied to the skin (topical medication) containing corticosteroids
• Cream or ointment containing a steroid-sparing immune-modulating medication, such as imiquimod (Aldara) or tacrolimus (Protopic)
• Oral corticosteroid medications, in severe cases
• Hydroxychloroquine

• Dapsone

Non-drug treatment

UVB Narrowband Phototherapy