Lichen planus
Lichen planus is an idiopathic, T-cell-mediated inflammatory disease producing pruritic, violaceous, flat-topped polygonal papules on flexor skin and lacy Wickham striae on mucosa, and it is a clinical diagnosis built on the classic 6 P's. First-line treatment is discontinuing any causative drug plus high-potency topical corticosteroids, reserving systemic corticosteroids for severe widespread disease.
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What this article covers
- Overview
Definition: lichen planus is an idiopathic, recurrent, T-cell-mediated, chronic inflammatory disease that affects the skin, oral mucosa, genitalia, nails, and scalp.
- Epidemiology
Age distribution: lichen planus occurs in both children and adults.
- Risk factors
Hepatitis C virus infection: the strongest recognized systemic association; screening is reasonable given that the U.S.
- Pathophysiology
T-cell-mediated cytotoxic injury: lichen planus is a T-cell-mediated inflammatory process directed against basal keratinocytes of the epidermis.
- Clinical features
Diagnostic criteria (6 P's): the diagnosis rests on recognizing planar (flat-topped), purple, polygonal, pruritic papules and plaques; when this constellation is present on the classic flexor…
- Differential diagnosis
Lichenoid drug eruption or contact dermatitis: morphologically similar violaceous papules, but occurs in a patient taking a new medication or using a new topical product, unlike idiopathic lichen planus with no such temporal trigger.
- Diagnosis
Diagnose clinically from the 6 P's and Wickham striae: recognition of planar, purple, polygonal, pruritic papules and plaques with lacy Wickham striae on the classic flexor and mucosal sites…
- Management
First, discontinue any medication that may be a potential cause, including ACE inhibitors, thiazide diuretics, and NSAIDs, since removing an offending drug can clear a lichenoid eruption without further treatment.
- Complications
Squamous cell carcinoma: erosive oral lichen planus carries a risk of oral squamous cell carcinoma, which is why persistent leukoplakic or erosive mucosal lesions require biopsy.
- Prognosis
Most cutaneous disease resolves within 1 year: approximately two-thirds of patients have spontaneous resolution of skin lesions within 1 year of onset.
- Prevention
One-time hepatitis C screening at age 18 to 79 years for all adults, per USPSTF guidance, with retesting at any age for patients who have ongoing HCV risk factors, given the documented HCV association with lichen planus.
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- Lichenoid drug eruption
Lichenoid drug eruption is a drug-induced form of lichen planus that develops insidiously, months to a year or more after starting a culprit drug, and can affect any body surface with violaceous, flat-topped papules resembling idiopathic lichen planus. Diagnosis rests on a temporal medication history plus morphology, and first-line treatment is identifying and stopping the causative drug, adding a high-potency topical corticosteroid and an oral antihistamine for symptom control while it clears.
- Pemphigus vulgaris
Pemphigus vulgaris is an autoimmune intraepidermal blistering disease in which IgG autoantibodies against desmoglein 3, often with desmoglein 1, destroy keratinocyte adhesion, producing flaccid, easily ruptured mucocutaneous bullae with a positive Nikolsky sign. Diagnosis is confirmed by skin biopsy with direct immunofluorescence and anti-desmoglein serology, and first-line treatment is rituximab 1,000 mg IV twice, two weeks apart, combined with a tapering corticosteroid course.