Lichen Planus: Causes, Recognition, and Treatment

Lichen planus is a chronic inflammatory condition that can affect the skin, mucous membranes, nails, and hair. It is characterized by polygonal, violaceous (purple-red), flat-topped papules with fine, net-like white lines (Wickham's striae) on the surface. The condition is immune-mediated, not infectious, and affects approximately 1–2% of the population — predominantly adults between 30 and 60 years of age. It affects both sexes equally, though oral lichen planus may be slightly more common in women.

Lichen planus is a T-cell-mediated autoimmune reaction directed against the basal cell layer of the skin. The exact triggers are not fully understood. Associations exist with hepatitis C infection, certain medications (beta-blockers, ACE inhibitors, NSAIDs), dental amalgam fillings, and contact allergens.

Stress can worsen flares. A genetic component is suspected, as the condition occasionally clusters in families. Drug-induced lichenoid reactions can mimic idiopathic lichen planus and should be considered in the differential.

The classic 5 Ps describe the skin lesions: pruritic (itchy), polygonal, planar (flat-topped), purple, and papules. Favored sites are the wrists, forearms, ankles, and lower back. Oral lichen planus presents as white streaks (reticular pattern), erosions, or ulcerations on the buccal mucosa, tongue, or gums.

Nail involvement can include ridging, thinning, or complete nail loss. The Koebner phenomenon — development of new lesions at sites of mechanical irritation — is common and may explain the distribution along scratch marks or belt lines.

Diagnosis is based on the clinical presentation — the typical Wickham's striae under dermatoscopy are often diagnostic. A skin biopsy confirms the diagnosis, showing the characteristic band-like lymphocytic infiltrate at the junction zone with damage to basal keratinocytes (interface dermatitis). For suspected oral lichen planus, biopsy is particularly important to exclude premalignant changes. Hepatitis C screening is recommended, as the association is well established in multiple studies.!!

Topical corticosteroids are first-line treatment for cutaneous lichen planus. High-potency steroids such as clobetasol propionate are used for skin lesions, while milder formulations are appropriate for mucous membranes. Calcineurin inhibitors (tacrolimus, pimecrolimus) offer a steroid-free option, especially for oral and genital forms.

For extensive involvement, systemic therapies may be considered: oral corticosteroids, retinoids (acitretin), methotrexate, or phototherapy (UVB, PUVA). Antihistamines help relieve itching.

Cutaneous lichen planus is usually self-limiting, resolving in most patients within 1–2 years, though it may leave post-inflammatory hyperpigmentation. Oral lichen planus often follows a chronic course requiring long-term management — since erosive forms carry a small risk of malignant transformation to squamous cell carcinoma, regular monitoring is important.!! Nail changes may persist. Relapses are possible, but the overall prognosis is good.

The distinctive purple, flat-topped papules of lichen planus can sometimes be confused with other inflammatory conditions such as psoriasis, drug eruptions, or eczema. Skinscanner analyzes the color, shape, and distribution of your skin lesions to help identify whether your symptoms are consistent with lichen planus. Regular photo documentation allows you to track the evolution of existing lesions, detect new ones early, and monitor your response to treatment over weeks and months.

This visual timeline is particularly valuable for managing a condition that can wax and wane unpredictably. For those with post-inflammatory hyperpigmentation after lichen planus resolves, Skinscanner can help you monitor gradual fading. Skinscanner does not replace dermatologic evaluation or biopsy — which may be needed for definitive diagnosis — but it provides helpful first-line assessment and ongoing monitoring support.