Lichen Planus:

Lichen planus is a disease that affects the skin, hair, and nails. Sometimes involving mucus membranes and genitals. It is characterized by shiny, flat-topped, polygonal, purplish skin lesions, often causing itching. It almost always heals leaving black marks.

Lichen planus is most common in adults aged 30-60 however, any age may be affected . It affects both genders equally, though some studies suggest a slightly higher prevalence in females. The exact cause is unknown, but it is considered to be an autoimmune disorder that may be triggered by certain medications, infections (especially hepatitis C), or allergens.

Clinical Features:

Skin lesions: Typically appear as purple, itchy, flat-topped papules, often on the wrists, ankles, and lower back.
Oral lichen planus: Appears as white, lacy patches, red swollen tissues, or open sores in the mouth.
Genital lesions: Similar lesions may appear on the genitals, causing pain or discomfort.
Nail changes: Thinning, ridging, and splitting of the nails; in severe cases, it can lead to permanent nail loss.
Scalp involvement: Lichen planopilaris can cause scalp scarring and permanent hair loss.
Drug induced lichen planus- some medications like ibuprofen, beta blockers, TNFalpha inhibitors may induce lichen planus.
Clinical presentations- skin lesions are commonly seen in the body, symmetric on both sides of the body. Small , apples, flat topped, purple to reddish, polygonal itchy lesions. Thin white lines may be seen over the lesions Wickham’s striae. Nails get long ridges and get rough. Oral erosions may be seen.

Lichen Plano Pilaris, primarily affects scalp.

Pathogenesis:

Lichen planus is believed to involve a T-cell mediated autoimmune reaction against basal keratinocytes, though the exact antigen is not identified. Stress, genetic predisposition, and environmental factors may contribute.

Diagnosis:

Diagnosis is primarily clinical but can be confirmed with a skin biopsy showing characteristic histological findings, including a band-like lymphocytic infiltrate at the dermoepidermal junction, basal cell degeneration, and Civatte bodies.

Treatment:

Treatment focuses on symptom relief and includes:

Topical corticosteroids : They are especially useful in treating new lesions and in mild cases. However their usage should be limited as prolonged usage can cause skin atrophy.
Systemic corticosteroids or immunosuppressants are used in severe cases- Steroid pulse therapy over the weekends with drug holidays in between are preferred as it helps to minimise the side effects. Immunosuppressants like methotrexate are useful in small doses especially in recurrent cases.
Antihistamines are useful in controlling itching.
Retinoids like acitretin is useful in treatment of thick, hypertrophic lichen planus. Light therapy like NB UVB is useful in generalised lichen planus cases where oral medications are contraindicated. Topical calcineurin inhibitors are used to maintain remission once active disease is treated.
Regular monitoring, especially in oral lichen planus, due to the small risk of progression to squamous cell carcinoma.

Prognosis:

The course of lichen planus is variable; many patients experience spontaneous remission within 1-2 years, though mucosal involvement tends to be more chronic and persistent.