Lichen planus

Lichen planus is a chronic inflammatory disease characterized by lesions involving the skin (i.e., cutaneous), mucosa (i.e., mucosal), and hair or nails (i.e., appendageal). It most commonly affects adults aged 30–60 years. The exact etiology is unknown. Cutaneous lichen planus typically manifests as pruritic purple papules and plaques with well-demarcated irregular borders and Wickham striae on the extremities (e.g., wrists and ankles). Mucosal lichen planus manifestations include papules, plaques, Wickham striae, and erosions on the oral, esophageal, and/or genital mucosa. Diagnosis is based on the presence of clinical features or typical histology; biopsy should be performed if the diagnosis is uncertain. Screening for hepatitis C should be considered for all patients. Early specialist consult is required for mucosal lichen planus and hypertrophic cutaneous lichen planus because of the risk of treatment resistance and the potential for malignant transformation to squamous cell carcinoma (SCC). First-line treatment consists of high-potency topical steroids; intralesional preparations are indicated for hypertrophic cutaneous disease and appendageal involvement.

• Prevalence: rare disease (occurs in < 1% of the population) ^[1][2]
• Age of onset: 30–60 years ^[3]
• Sex ^[1]
  • Cutaneous lichen planus: ♀=♂
  • Oral lichen planus is more common in women

Epidemiological data refers to the US, unless otherwise specified.

Although the exact etiology of lichen planus is unknown, possible etiologic factors include:

• Altered immune response with T cell activation ^[4][5]
• Associated with hepatitis C infections ^[6]

Lichen planus is categorized based on the areas of involvement: cutaneous, mucosal, and appendageal. The most common cutaneous and mucosal manifestations are presented here. Additional manifestations are described in “Subtypes and variants.” ^[1]

Cutaneous lichen planus ^[2][7]

• 6 Ps of cutaneous lichen planus
  • Purple (violaceous)
  • Polygonal, irregular borders
  • Planar (flat-topped)
  • Pruritic, often severe
  • Papules
  • Plaques
• Wickham striae: white reticular lines on the surface of the lesions
• Bilateral, symmetrical involvement of the extremities (e.g., ankles, flexor wrists) and, in some cases, the trunk
  • Lesions are arranged in linear or circular groups that may coalesce into larger plaques.
  • Koebner phenomenon
• See also hypertrophic cutaneous lichen planus in “Subtypes and variants.”

Mucosal lichen planus ^[2][7]

See “Subtypes and variants” for information on esophageal lichen planus.

• Oral lichen planus ^[1][7][8]
  • Affects the buccal mucosa, gingiva, and tongue
  • Reticular type: Wickham striae, asymptomatic
  • Erythematous type: atrophic erythematous plaques
  • Erosive type: erosions associated with pain and a burning sensation
• Genital lichen planus
  • All patients
    • Papules, Wickham striae, and, if severe, scarring and adhesions
    • Pruritus, a burning sensation, or dyspareunia may be present.
  • Male genitalia: annular lesions on the glans penis and coronal sulcus ^[9]
  • Female genitalia: erosions on the labia, clitoris, and vagina ^[10]

The 6 Ps of cutaneous lichen Planus: Purple, Polygonal, Planar (flat-topped), Pruritic, Papules, and Plaques

Postinflammatory hypopigmentation and postinflammatory hyperpigmentation may be present. ^[1]

Hypertrophic cutaneous lichen planus ^[2][7]

• A subtype of cutaneous lichen planus; also called lichen planus verrucosus
• Scaly; , hyperkeratotic, verrucous plaques and nodules
• Predominantly affect the shins, ankles, and interphalangeal joints
• Severely pruritic

Esophageal lichen planus ^[7]

• A subtype of mucosal lichen planus
• Symptoms: dysphagia, odynophagia
• Endoscopic findings: strictures, papules with Wickham striae, erosions, sloughing, stenosis ^[11]

Appendegeal lichen planus ^[7]

Lichen planopilaris ^[7]

• Mainly affects the scalp of postmenopausal women and presents with pruritus, hair loss
• Frontal fibrosing alopecia (a variant of lichen planopilaris)
  • Affects the scalp with scarring alopecia
  • Histology: hair follicles are surrounded by a bandlike lymphocytic infiltrate
  • Direct immunofluorescence shows subepidermal colloid bodies

Nail lichen planus ^[7]

• A type of appendageal lichen planus
• Nail features
  • Thinning, atrophy, onycholysis, longitudinal ridging
  • Subungual hyperkeratosis
  • Discoloration (e.g., yellow)

Lichen planus is a clinical diagnosis. Diagnostic studies are indicated in patients with atypical, extensive, or refractory lesions. ^[2][7]

• Dermoscopy: to improve visualization of lesions (e.g., Wickham striae), especially in individuals with darker skin
• Biopsy: to exclude differential diagnoses and malignancy; see “Pathology” for histopathologic findings ^[12]
• Endoscopy for symptoms of esophageal involvement
• Laboratory studies: Consider HCV screening, especially in individuals with risk factors for HCV infection. ^[1][2]

Perform a history and physical examination to assess all potential areas of involvement (i.e., cutaneous, mucosal, appendageal). ^[7]

• Hyperkeratosis
• Wedge-shaped hypergranulosis ^[13]
• Irregular acanthosis (saw-tooth appearance) ^[13]
• Band-like lymphocytic infiltrate at the dermal-epidermal junction ^[14]

• Skin lesions ^[2]
  • Drug-induced lichen planus (lichenoid drug eruption) ^[1][7]
    • A dermatologic condition triggered by certain medications (e.g., beta blockers, ACE inhibitors, penicillamines, thiazide diuretics, hydroxychloroquine)
    • Manifests with diffuse lesions that closely resemble lichen planus but are not histologically identical
    • Management includes topical glucocorticoids and discontinuation of the causative medication.
  • Eczema
  • Psoriasis (guttate psoriasis and plaque psoriasis)
  • Lichen simplex chronicus
  • Pityriasis rosea
  • Prurigo nodularis
  • See also “Maculopapular rash” and “Differential diagnosis of scaling.”
• Oral lesions ^[2]
  • Oral thrush
  • Leukoplakia
  • Bite trauma to buccal mucosa
• Genital lesions ^[7][9]
  • Lichen sclerosus
  • Lichen simplex chronicus
  • Squamous cell carcinoma

Chronic graft-versus-host disease can manifest with cutaneous and mucosal lesions that resemble lichen planus. ^[15]

The differential diagnoses listed here are not exhaustive.

Cutaneous lichen planus (non-hypertrophic) ^[1][2][7]

• High-potency or ultra-high potency topical steroid (first-line), e.g., clobetasol
• Oral antihistamines, e.g., hydroxyzine, as needed for pruritus.
• Reassess after 1–3 months; adjust treatment based on clinical response. ^[1][10]
• For patients with refractory disease, refer to dermatology for biopsy and advanced treatments.
  • Oral steroids, e.g., prednisone (off-label)
  • Phototherapy (UVB and PUVA)
  • Oral retinoids (e.g., acitretin)
  • Topical calcineurin inhibitors (e.g., pimecrolimus, tacrolimus)
  • Methotrexate
  • Novel therapies: JAK inhibitors, PDE-4 inhibitors, biologic immunomodulators (e.g., interleukin inhibitors)

Topical calcineurin inhibitors are associated with a theoretical risk of malignancy and must be used with caution, particularly in mucosal and hypertrophic cutaneous lichen planus. ^[8]

Hypertrophic or noncutaneous lichen planus ^[1][2][7][8]

Refer to appropriate specialists (e.g., dermatology, oral surgery, urology, gynecology) for management and long-term monitoring for complications (e.g., scarring, SCC). ^[7][8][10]

• Glucocorticoids
  • Mucosal lichen planus flares (e.g., painful erosions): off-label use of topical or oral steroids
  • Appendageal and hypertrophic cutaneous lichen planus: intralesional glucocorticoids
• Adjunctive treatments for symptomatic relief
  • Pruritus: hydroxyzine
  • Oral pain: lidocaine mouthwash
  • Dyspareunia: water-based lubricants
• Prevention of complications
  • Oral hygiene and smoking cessation ^[8]
  • Foreskin hygiene or vaginal dilators
• Advanced treatments for refractory disease or complications
  • Advanced treatments are similar to those used for refractory cutaneous lichen planus.
  • Surgery or dilatation may be needed for mucosal scarring, adhesions, or stenosis.

Treatment is generally not indicated for asymptomatic mucosal lichen planus; reserve treatment for symptomatic flares (e.g., painful erosions). ^[8]

Mucosal, hypertrophic cutaneous, and appendageal lichen planus are associated with malignant transformation to squamous cell carcinoma. ^[7]

Any localization of erosive lichen planus can cause scarring, which may lead to functional limitations.

• Cutaneous lichen planus
  • Usually self-limited (typically resolves within 1 year) ^[1]
  • Can cause lasting hypopigmentation and/or hyperpigmentation
• Oral lichen planus
  • Chronic condition
  • Potential for malignant transformation into squamous cell carcinoma
• Genital lichen planus: may lead to scarring and/or synechiae formation