Lichen planus is characterized by lesions on the skin, mucous membranes or nails. Affected areas are typically mild to severely pruritic (itchy) and may be red and swollen. Skin lesions are red or violet and shiny. They are flat topped and may be about 0.8 to 1.5 inches (2 to 4 centimeters) in diameter. They may group together into rough, scaly plaques. Lesions are often covered in white spots or lacy white lines called Wickham’s striae and scales may form over them in later stages. The borders of the lesions are distinct and angular.

Skin lesions are generally symmetrical and localized. Lesions are usually distributed on both sides of the body. They occur most often on the inner surfaces of the arms, legs, hands and feet. They also appear on the trunk and genitals. However, the first signs of the condition almost always appear in the limbs. The face is rarely affected. New lesions may form from scratching or where a mild skin injury occurs. Sometimes, a dark brown discoloration may remain after the lesions disappear. This usually fades over time and is more common in people with darker skin.

Lesions on the legs are generally darker in appearance and thick patches can form on the shins. Rarely, blisters may form in the lesions. When the scalp is involved, permanent hair loss may result.

According to the American Academy of Dermatology (AAD), about 20 percent of women with lichen planus will experience some sort of genital lesions. Genital involvement is less frequent in men. Women with genital lesions may experience burning, redness and rawness in the vaginal area. Increased vaginal discharge can also occur. Sexual intercourse may be very painful and result in bleeding. Lichen planus lesions may also scar, resulting in closure of the vagina. Men most often develop lesions around the tip of the penis.

Lesions may also occur in the mouth. In some cases, the mouth is the only area of the body affected. Mouth lesions may cause dry mouth or a metallic taste in the mouth. The lesions are usually poorly defined gray-white or blue-white spots, but sometimes only Wickham’s striae (lacy patches) occur. Mouth lesions often remain unnoticed by patients, only being discovered by dentists during routine exams. However, severe forms of the condition can cause lesions that are tender and painful. Lesions are usually located on the inside of the cheeks but may also occur on the sides of the tongue or, rarely, on the gums. Sometimes, these mouth lesions erode to form painful ulcers. Some patients may find it hard to eat. Redness and bleeding of the gums may also occur.

Lichen planus lesions may also affect one or more nails on the hands or the feet. In most cases, only a few nails are affected. There may be longitudinal ridging or grooving or splitting of the nail surface and the nails may become thin. Darkening of the nail may also occur. Some cases result in nail loss that may be temporary or permanent.