Lichen Planus

Lichen Planus

Lichen planus (LP) is a disease of the skin and, less often, the scalp, fingernails, toenails, and/or inside the mouth or genitalia (mucous membranes). Lichen planus can resolve on its own without treatment or be chronic, even with aggressive treatment. The cause of the inflammation that leads to lichen planus is unknown.

People of all ages, of all races, and of both sexes can have lichen planus. However, it is rarely seen in young children and older adults, most commonly occurring in people aged 30-60.

Although the cause of lichen planus is unknown, some people with the condition also have hepatitis C, an infection of the liver.

People who take certain medications may develop a rash that looks like lichen planus (drug-induced lichen planus). These medications include:

  • High blood pressure (hypertension) medicines, including diuretics, ACE inhibitors, and calcium channel blockers

  • Diabetes medications, including the sulfonylureas

  • Ibuprofen or naproxen

  • Antimalarial medications

  • Gold

  • Penicillamine

  • Ketoconazole

The most common locations for lichen planus include:

  • Inner wrists

  • Forearms

  • Inner ankles

  • Lower legs

  • Neck

  • Trunk

  • Inside the mouth

  • Fingernails and toenails

  • Scalp

  • Genitals

Individual lesions of lichen planus on the skin appear as small (1-5 mm), flat-topped, red-to-purple bumps. As lichen planus progresses, the surfaces of these bumps can become dry and scaly and can develop wispy, gray-to-white streaks (Wickham’s striae). Lichen planus on the skin is usually itchy.

New lesions of lichen planus can be caused by injury (trauma). This so-called Koebner phenomenon may appear as a line of flat-topped, red-to-purple bumps on the skin.

Once they heal, lichen planus lesions often leave behind patches of darker (hyperpigmented) skin, which are more pronounced in darker-skinned people and which may take months to return to their normal color.

In the mouth, lichen planus appears as white, net-like patches, most often seen on the inner cheeks. This oral lichen planus does not usually cause symptoms, though severe outbreaks may develop painful sores and ulcers in the mouth.

When lichen planus involves one or more fingernails or toenails, it can appear as  a thickening, splitting, ridges, or grooves. In severe outbreaks, the entire nail may be destroyed.

On the scalp, lichen planus (called lichen planopilaris) may cause redness, irritation, and, in some cases, permanent hair loss.

On the penis, the lichen planus appears similar to lesions on other areas of the skin. In the vulva or vagina, lichen planus may appear as bright red patches or sores. Genital lichen planus does not usually cause symptoms, but open sores may be quite tender.

If you develop an itchy, bumpy rash, see a dermatologist or another physician for evaluation.