Lichen planus is an uncommon disorder involving a recurrent, itchy, inflammatory rash or lesion on the skin or in the mouth. The exact cause is unknown, but the disorder is likely to be related to an allergic or immune reaction.

The disorder has been known to develop after exposure to potential allergens such as medications, dyes, and other chemical substances. Symptoms are increased with emotional stress, possibly because of changes in immune system during stress.

Lichen planus generally occurs at or after middle age. It is less common in children. The initial attack may last for weeks to months, resolve, then recur for years.

Lichen planus may be associated with several other disorders, most notably hepatitis C.

Chemicals or medications associated with development of lichen planus include gold (used to treat rheumatoid arthritis), antibiotics, arsenic, iodides, chloroquine, quinacrine, quinidine, antimony, phenothiazines, diuretics such as chlorothiazide, and many others.

• Itching in the location of a lesion, mild to severe
• Skin lesion:
  • Usually located on the inner areas of the wrist, legs, torso, or genitals
  • Generalized, with symmetric appearance
  • Single lesion or clusters of lesions, often at sites of skin trauma
  • Papule of 2 - 4 cm size
  • Papules clustered into a plaque or large, flat-topped lesion
  • Distinct, sharp borders to lesions
  • Possibly covered with fine white streaks or linear scratch marks called Wickham's striae
  • Shiny or scaly appearance
  • Color dark -- reddish-purple (skin) or gray-white (mouth)
  • Possibility of developing blisters or ulcers
• Ridges in the nails (nail abnormalities)
• Dry mouth
• Metallic taste in the mouth
• Mouth lesions
  • Tender or painful (mild cases may have no discomfort)
  • Located on the sides of the tongue or the inside of the cheek
  • Occasionally located on the gums
  • Poorly defined area of blue-white spots or "pimples"
  • Linear lesions forming a lacy-appearing network of lesions
  • Gradual increase in size of affected area
  • Lesions occasionally erode to form painful ulcers
• Hair loss

Your physician will suspect lichen planus based on the distinctive appearance of the lesions. Your dentist may diagnose oral lichen planus based on the distinctive appearance of mouth lesions. A skin lesion biopsy or biopsy of a mouth lesion can confirm the diagnosis.

The goal of treatment is to reduce your symptoms and speed healing of the skin lesions. If symptoms are mild, no treatment may be needed.

Treatments may include:

• Antihistamines
• If you have mouth lesions, lidocaine mouth washes may numb the area temporarily and make eating more comfortable.
• Topical corticosteroids (such as triamcinolone acetonide cream) or oral corticosteroids (such as prednisone) may be prescribed to reduce inflammation and suppress immune responses. Corticosteroids may be injected directly into a lesion.
• Topical retinoic acid cream (a form of vitamin A) and other ointments or creams may reduce itching and inflammation and may aid healing.
• Occlusive dressings may be placed over topical medications to protect the skin from scratching.
• Ultraviolet light therapy may be beneficial in some cases.

Lichen planus is generally not harmful and may resolve with treatment, but can persist for months to years. Oral lichen planus usually clears within 18 months.

Long-standing mouth ulcers may develop into oral cancer.

Call your health care provider if symptoms persist, or if there are changes in the appearance of skin or oral lesions.

Call for an appointment with your health care provider if oral lichen planus persists or worsens despite treatment, or if your dentist recommends adjustment of medications or treatment of conditions that trigger the disorder.