see also:

• dermatology

• a chronic skin and mucosal autoimmune T-cell mediated condition

• affects 1% of the population
• mainly those aged 30-60yrs

• genetic
• may be precipitated by:
  • stress
  • infections eg. zoster, hepatitis C virus
  • medications eg. gold, quinine, quinidine - may cause a lichenoid drug eruption
  • contact allergy eg. colour photographic developers, metal tooth fillings
  • vit D deficiency may be associated with oral forms

• cutaneous
  • usually pruritic
  • shiny, flat topped, firm polygonal plaques and papules which are often purplish when new (yellow-brown on palms and soles)
    • Wickham striae are white lines crossing the plaques
    • most often on front of wrists, lower back and ankles
    • last months and resolve to greyish-brown macules which usually last over a year
  • may be scaly, pruritic rash which may be confused with SCC
  • may have distribution over sun damaged skin areas
  • may have Koebner's phenomenon - linear following scratch lines
  • may be scattered or clustered
  • may have central atrophy
  • annular versions have violaceous plaques with central clearing - often occur in genital/perianal areas
• lichen planus pigmentosus
  • ill-defined pigmented lesions usually mainly on sun exposed areas
• lichen planus actinicus (LPA)
  • mainly young adults from Middle East and surrounding regions
  • usually triggered bu UV exposure
• scalp
  • lichen planopilaris
    • tiny red spiny follicular papules leading to alopecia patches with sparse hairs and smooth skin
    • frontal fibrosing alopecia
      • effects anterior scalp, forehead, eyebrows
  • pseudopelade of Brocq
• nails
  • thins the nail plate causing grooves and ridges
  • nail may darken and lift off and may shed and not regrow if the cuticle is destroyed
• mucosal
  • oral
    • usually painless white streaks or lacy pattern on buccal mucosa, lip or tongue
    • may have painful erosive ulcers
    • may have desquamative gingivitis, especially near amalgam dental fillings
  • vulval
    • similar lesions as oral
    • may cause vaginal discharge and painful intercourse with easy bleeding if erosive form
  • penile
    • classical is a ring of papules around the glans
  • other areas
    • may occur in oesophagus (may cause strictures and dysphagia), larynx, bladder, anus, eyes, external ear canal

• skin biopsy

• avoid drying out skin, use regular emollients
• Rx nocturnal pruritis with sedating antihistamines
• a range of medication options can be considered if troublesome including steroids, topical retinoids, intralesional steroid injections, etc
  • referral to dermatologist to consider the options