Lichen Planus

Most common lichenoid disorder; lichenoid disorders are conditions characterised by damage to basal epidermis

Aetiology

  • Chronic inflammatory disease of unknown origin
  • Association with Hepatitis C

Clinical presentation

  • Itchy flat-topped violaceous papules
  • Distribution: flexor surfaces of wrist/forearm, ankles, legs
    • Can devop at site of trauma
  • Oral lesions - lacy white lesions on the inside of the cheek

Investigations

Biopsy

  • Diagnosis usually clinical but can be used to confirm, especially if considering SCC as a differential
  • Findings:
    • Irregular sawtooth acanthosis
    • Hypergranuloss and orthohyperkeratosis
    • Band-like upper dermal infiltrate of lymphocytes
    • Basal damage with formation of cytoid bodies
notion image

Management

  • Topical steroid + antihistamine

Other lichenoid disorders

  • Some resemble lichen planus e.g. discoid lupus, some drug rashes
  • Some life-threatening varients e.g. erythema multiforme, toxic epidermal necrolysis have a more marked vascular interface change - target lesions (annular shaped macules that are raised with a red rim and centre with a wedge of normal skin inbetween)