What is lichen planus? Common symptoms include

Lichen planus, an inflammatory skin disease, can affect the mucous membranes, skin, nails, hair, etc. It is usually accompanied by obvious itching symptoms when it occurs. It is most common in middle-aged people. Dark red or purple skin is a typical symptom.

1. Typical lichen planus

This disease is more common in adults, with a high incidence age of 30 to 60 years old. It is rare in children and the elderly, and is slightly more common in women than in men. Typical skin lesions are purple or dark red, reddish brown pinhead to lenticular polyhedral flat papules with clear margins and a surface covered with a thin layer of waxy, adhesive scales (Figures 1, 2). Sometimes a slight concave center or tiny keratin plugs can be seen. The surface of the papules has grayish-white spots and interlaced reticular stripes, called Wickham lines, which become clearer after being smeared with liquid oil. The lesions initially appear as red spots, which develop into purple-red papules after a few weeks. Sometimes it can develop and spread rapidly in a short period of time. The skin lesions may merge with each other, presenting as lichenoid patches of varying sizes and shapes, surrounded by scattered rashes (Figures 3, 4). In the acute phase, linear isomorphic reactions may occur after scratching. The rash can occur anywhere on the body, often symmetrically, and is most common on the flexor sides of the limbs, medial thighs, popliteal fossa, buttocks and waist, and also often occurs on the neck. The patients may feel itchy to varying degrees, even severely, and a few may have no symptoms.

2. Drug-induced lichen planus

Drug-induced lichen planus occurs after injection, contact, or inhalation of certain chemicals. The time when skin lesions appear ranges from several months to 1 year or longer after medication, which is related to the dosage, individual sensitivity, exposure and usage of the drug. The time for skin lesions to disappear varies, usually 3 to 4 months. The disappearance of lichenoid rash caused by gold preparations may take 2 years after stopping the medication. The rash may be typical or atypical of lichen planus, presenting as localized or generalized eczematous papules and plaques, irregular polygons, post-inflammatory pigmentation, alopecia and loss of typical Wickham lines, often occurring on the trunk and limbs, and often with symmetrical eruptions. Mucosal involvement is less common.

The course of this disease is chronic, lasting for several months to several years, and most cases disappear on their own within 1 to 2 years. Oral lesions can persist for more than 20 years. Temporary pigmentation, hypopigmentation or atrophic scars may remain after healing.

3. Atypical lichen planus The clinical manifestations of lichen planus vary. There are many types according to the onset, rash morphology and different arrangements.

4. Atrophic lichen planus (lichen planus atrophicans ) This type can be divided into primary and secondary types. The primary type is rare. The lesions are polygonal, with central atrophy, keratin plugs at the hair follicle openings and sweat pores, and hypopigmentation in the atrophic areas, forming small pale white spots that can merge into large plaques. It is common on the limbs and trunk. This type should be distinguished from morphea

guttate) and lichen sclerosus atrophicus. Secondary cases are often seen during the regression process of annular lichen planus or hypertrophic lichen planus. Histopathology showed that the epidermis and epidermal appendages were atrophied, with little cell infiltration and unclear infiltration zones.

5. Bullous lichen planus (lichen planus bullous) This type is rare. Small or large blisters often appear on primary papules, plaques or normal skin, and their size is consistent with that of the papules or plaques. The contents of the blisters are clear, and sometimes bloody. Blisters may appear in the acute phase of lichen planus, accompanied by moderate discomfort, and may disappear within a few months. Skin lesions often occur on the lower limbs, and bullous erosions may also appear on the oral mucosa, causing conscious pain. Histologically, there are typical lichen planus changes. The clinical manifestations of bullae occurring on normal skin are similar to those of pemphigus or dermatitis herpetiformis, but with typical lichen planus tissue appearance. Direct immunofluorescence examination of the bullae shows IgG, IgM, and C3 deposition in the basement membrane area, and circulating anti-basement membrane antibodies are present in the serum. It often occurs on the basis of acute generalized lichen planus. This type is rare and should be differentiated from pemphigus.

6. Lichen planus follicularis, also known as lichen planopilaris, is more common in adult women. It may occur alone in hair follicles or in combination with other lichen planus skin and mucosal lesions. The lesions are obvious follicular papules and nut-like plaques, and hair loss over time may form atrophic scars. In addition to the scalp, it is prone to occur on the neck, shoulder blades, chest and outer sides of the limbs. Follicular lichen planus of the skin and/or scalp. Scarring alopecia of the scalp and non-scarring alopecia of the axilla and pubis are called Graham-Little-Pic

Cardi-Lassueur triad. In addition to typical lichen planus tissue images, histopathological findings also showed follicular keratin plugs and significant infiltration of the hair follicle roots. This type should be distinguished from keratosis follicularis, tuberculous lichen, and discoid lupus erythematosus.