Lichen planus (Lichen planus)

Lichen planus is a chronic inflammatory disease of the skin, mucous membranes, nails and/or hair, suspected to be of autoimmune origin. It is characterized by the appearance of itchy, flat, pink-red papules with a shiny surface. It occurs most often between the ages of 30 and 60 and affects both men and women.

Causes and mechanisms
The cause of the disease is not fully understood. It is thought to be related to an abnormal T-cell immune response against keratinocytes. Possible triggering factors include:
- infections (especially hepatitis C)
- medications (NSAIDs, beta-blockers, ACE inhibitors, gold salts)
- contact with dental materials
- stress

Clinical forms and symptoms
1. **Cutaneous lichen planus**:
- Itchy, pinkish-red, flat papules with a shiny surface
- Most often on wrists, ankles, lower back, forearms
- Fine white lines are often observed on the surface – the so-called *Wickham's striae*
- May leave hyperpigmentation upon healing
2. **Oral lichen planus**:
- White net-like lines on the mucous membranes of the cheeks, tongue and gums
- Sometimes erosions, burning, pain when eating
- Can become chronic and rarely transform into malignant lesions (erosive form)
3. **Nail lichen planus**:
- Longitudinal furrows, thinning of the nail, delamination
- In advanced cases – complete loss of the nail (anonychia)
4. **Scalp (lichen planopilaris)**:
- Inflammation of the hair follicles with subsequent atrophy and irreversible hair loss (cicatricial alopecia)

Diagnosis

The diagnosis is made based on a clinical examination, and is often confirmed by skin or mucosal biopsy. If in doubt, additional tests are performed - for hepatitis C, blood count, liver enzymes, etc.

Treatment
Treatment is determined according to the form and severity of the disease:
- Topical corticosteroids – first line for cutaneous and mucosal forms
- Calcineurin inhibitors – for sensitive areas (e.g. oral mucosa)
- Systemic corticosteroids – for severe, extensive or erosive forms
- Retinoids (Acitretin, Isotretinoin)
Cyclosporine (for mucosal form)
Methotrexate, Dapsone, Azathioprine

Forecast
The cutaneous form is often self-limited within 6–18 months. However, oral and scalp forms may become chronic and require prolonged monitoring. Regular monitoring is recommended for erosive mucosal lesions due to the minimal risk of malignant transformation.

Lichen planus is a chronic but manageable disease. Early diagnosis and appropriate therapy reduce the risk of complications and improve quality of life.