• Clinical science

Lichen planus


Lichen planus is a chronic inflammatory disease of unknown origin that is characterized by different types of lesions involving the skin and mucosa in middle-aged individuals. The most common lesions are purple papules with well-demarcated, irregular borders, which typically occur on the wrists, lower extremities, and genitoanal region. The surfaces of the lesions often exhibit a pattern of white lines known as Wickham's striae. The disease is diagnosed clinically, but may be confirmed through dermoscopy and punch biopsies. Biopsy also helps detect squamous cell carcinoma, a possible complication of genital lichen planus. Treatment primarily consists of high-dose topical steroids, but may also include oral steroids and phototherapy in cases of extensive or steroid-refractory disease.



Epidemiological data refers to the US, unless otherwise specified.


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


Clinical features

Lichen planus may affect the skin, mucosa, scalp, genitalia and nails, and presents with varying symptoms depending on the subtype of the disease. The condition is chronic and usually manifests with several relapses.

Cutaneous lichen planus

  • Primary lesion
    • Purple papules, well-demarcated
    • Planar (flat-topped)
    • Polygonal, irregular borders
    • Pruritic, often severe
    • Wickham's striae: pattern of white lines on the lesion's surface
  • Distribution pattern
    • Affects the extremities, especially the ankles and flexor wrists; trunk
    • Lesions arranged in linear or circular groups; may coalesce into larger plaques
    • Bilateral, symmetrical distribution
  • Manifests with the Koebner phenomenon
  • May occur simultaneously with other subtypes

Mucosal lichen planus

  • Oral lichen planus
  • Esophageal lichen planus
    • Submucosal papules, mucosal plaques, and erosions
    • Possible dysphagia and painful swallowing

Genital lichen planus

The 5 P's of lichen planus: Pruritic, Polygonal, Planar (flat-topped), Purple papules, and Plaques!



Lichen planus is clinically diagnosed based on the presence of typical skin lesions. Additional testing is performed to confirm the diagnosis and rule out other diseases.




Differential diagnoses

Lichen sclerosus (et atrophicus)



The differential diagnoses listed here are not exhaustive.