Lichen planus is a chronic inflammatory skin disease of unknown cause. The typical skin lesions are purple-red polygonal flat papules, often accompanied by oral mucosal damage. Mental stress, viral infections, and immune abnormalities may be contributing or predisposing factors for this condition. Lichen planus is often associated with immune-related systemic diseases and can be triggered by certain medications.

bubble_chart Clinical Manifestations

1. The characteristic skin lesion is a violaceous, polygonal, flat papule with well-defined margins, firm and dry texture, smooth surface with a waxy sheen, and grayish-white spots or reticular white streaks (Wickham's striae) visible under magnification. 2. It commonly occurs on the flexor surfaces of the limbs, popliteal fossa, ankles, and anterior tibia, but can also spread extensively over the body. 3. Nail and mucous membrane involvement may occur; a distinctive nail feature is pterygium-like changes. 4. Intense itching is typical, and the course is chronic. 5. The condition has many distinct clinical variants, such as pigmented lichen planus, hypertrophic lichen planus, bullous lichen planus, actinic lichen planus, follicular lichen planus, and palmoplantar lichen planus.

bubble_chart Diagnosis

1. Purple-red polygonal flat papules, firm and dry, with a smooth, waxy surface and clearly defined edges; 2. Occurs on the flexural sides of the limbs, popliteal fossa, ankles, and anterior tibia, or all over the body; 3. Nails and mucous membranes may be affected; 4. Intense itching is common, and the course of the disease is prolonged; 5. Characteristic histopathological changes are present.

Principles of Treatment
1. Antipruritic and anti-allergic therapy; 2. Vitamin therapy; 3. Corticosteroid therapy; 4. Physical therapy (1) PUVA therapy; (2) Laser; (3) Cryotherapy; 5. Topical medication; 6. Oral medication; 7. Chinese medicinals therapy.

Principles of Medication
1. Currently, there is no satisfactory mental therapeutics for this disease; 2. For localized and small-area skin lesions, topical medication alone may suffice; intralesional injection therapy, laser, or cryotherapy can be used for individual stubborn lesions; 3. Hypertrophic patches and nail lesions may be treated with intralesional corticosteroid injections; 4. For oral lesions with erosion and exudation, oral medications can be selected; stubborn erosive oral lesions may be surgically excised; 5. For acute onset with extensive and severe skin lesions, systemic corticosteroids may be used; 6. Retinoids are only used for stubborn sexually transmitted disease cases; 7. Sunlight-induced lichen planus can be treated with photoprotective agents; 8. Select 1-2 types of antihistamines based on the degree of cutaneous pruritus.

bubble_chart Cure Criteria

1. Cured: Symptoms and signs disappear without recurrence; 2. Improved: Symptoms and signs alleviate, with skin lesions reduced in number. 3. Not cured: Symptoms and signs show no improvement; or symptoms and signs disappear but recur within 2 weeks.