Lichen planus

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Alternate names

Actinic LP; Lichen planus actinus; Lichen planus subtropicus; Lichen planus tropicus; Lichenoid melanodermatitis; Summertime actinic lichenoid eruption


Lichen planus (LP) is an inflammatory disorder of the skin and mucous membranes with no known cause. It appears as pruritic, violaceous papules and plaques most commonly found on the wrists, lower back, and ankles.

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  • The prevalence of cutaneous LP is approximately 0.2% to 1% of adults worldwide.
  • Oral LP is more common and reported in 1% to 4% of the population.
  • Overall, women are more frequently affected than men at a ratio of 1.5:1, and most cases develop between the ages of 30 and 60.
  • It is rare in children as they represent less than 5% of all LP patients.


  • Its pathogenesis is not fully understood, but it appears to represent a T-cell-mediated autoimmune disease.
  • The prevailing theory is that exposure to an exogenous agent such as a virus, drug, or contact allergen causes alteration of epidermal self-antigens and activation of cytotoxic CD8+ T cells.
  • The altered self-antigens cross-react with normal self-antigens found on basal keratinocytes resulting in T-cell targeting and apoptosis.
  • A variety of agents have been associated with the development of LP, but a particular note has been made of the link with viruses, especially the hepatitis C virus (HCV).
  • Oral lichen planus is correlated with contact allergies to a variety of metals found in dental restorations including mercury, copper, and gold.
  • A large number of drugs have been associated with LP, but recurrence of lesions following drug rechallenge is rare.
  • More commonly associated drugs include antimalarials, ACEIs, thiazide diuretics, NSAIDs, quinidine, beta-blockers, tumor necrosis factor (TNF)-alpha inhibitors, and gold.

Signs and symptoms

  • Lichen planus can display a variety of lesion types, but the most common presentation is an area of polygon-shaped, itchy, violaceous, flat-topped papules a few millimeters wide.
  • This classic presentation is known as The Six Ps of LP: purple, polygonal, planar, pruritic papules, and plaques.


Various subtypes of LP exist that display patterns different from the classic presentation.

  • Hypertrophic LP is often found on the shins and ankles and is characterized by red, red-brown, or yellow-grey papules and plaques that coalesce with a thickened or verrucous surface.
  • Ulcerative LP is found on the soles of the feet or between the toes with painful, erosive lesions that make walking difficult.
  • Bullous LP appears most often on the legs as small to large tense blisters filled with clear or pale-yellow fluid.


  • While in the clinic, dermoscopy allows visualization of Wickham striae in most cases.[2][2].
  • A network of white lines with red globules along the periphery is the classic finding.
  • Oral LP lesions located near dental restorations should prompt patch testing to determine if an allergy to one of the associated metals exists.
  • Biopsy with the microscopic analysis is the most useful tool to confirm the presence of LP.
  • Lesions have many characteristics as noted previously that typically allow a definitive diagnosis.


  • Cutaneous LP typically clears spontaneously within 1 to 2 years, so treatment is aimed at reducing pruritus and time to resolution. For limited LP, first-line treatment is superpotent topical steroids (clobetasol 0.05%) twice daily for 2 to 4 weeks.
  • For diffuse LP, first-line treatment is daily oral corticosteroids (prednisone 30 to 60 mg) tapered over 2 to 6 weeks. If no change is seen, second-line therapy should be considered. Second-line therapy may include metronidazole (500 mg twice daily for 3 to 8 weeks), sulfasalazine (500 mg twice daily increased in 500 mg increments every 3 days until 2.5 grams daily is reached, for 3 to 6 weeks), isotretinoin (10 mg twice daily for 2 months), acitretin (30 mg daily for 8 weeks), PUVA, UVB, topical calcineurin inhibitors, or methotrexate (15 mg per week for adults, 0.25 mg/kg per week for children).
  • Third line treatment may include trimethoprim-sulfamethoxazole, griseofulvin, terbinafine, antimalarials, tetracyclines, ciclosporin,
  • mycophenolate mofetil, azathioprine, etanercept, adalimumab, or low-molecular-weight heparin

Oral LP may spontaneously resolve within 5 years, but many cases are chronic and never resolve.

  • Treatment-induced remission is typically followed by relapse.
  • Thus, asymptomatic oral LP should not be treated as the side-effect burden of treatment is high.
  • The goal for treatment of symptomatic oral LP is to heal erosive lesions to reduce pain and allow normal food intake.
  • Patients should be instructed to avoid spicy or acidic foods as well as alcohol and tobacco as these exacerbate symptoms.
  • First-line treatment is very high potency topical steroids three times daily until remission.
  • Second-line treatment is oral corticosteroids or application of topical calcineurin inhibitors.
  • Third-line treatment may include cyclosporine, azathioprine, mycophenolate mofetil, or methotrexate.

Consideration of drug-induced LP must always be explored prior to starting therapy.

  • Withdrawal of the suspected drug leading to the gradual disappearance of lesions confirms the diagnosis, although it may take some time for lesions to fully resolve.[3][3].


  • Cutaneous LP often clears spontaneously within 1 to 2 years, but residual hyperpigmentation is very common.
  • Oral LP may clear spontaneously within 5 years, but typically it is a chronic disease with a remitting and relapsing course.
  • Hair loss from LPP is permanent. Drug-induced LP lesions clear slowly after the causative medication is withdrawn.


  1. Arnold DL, Krishnamurthy K. Lichen Planus. [Updated 2020 Aug 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from:
  2. Arnold DL, Krishnamurthy K. Lichen Planus. [Updated 2020 Aug 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from:
  3. Arnold DL, Krishnamurthy K. Lichen Planus. [Updated 2020 Aug 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from:

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Lichen planus is a rare disease.

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