Lichen Planus

Figure 3.10 A: Annular lichen planus (Courtesy of Dr. Paul Getz) B: Blaschkoid lichen planus (Courtesy of Dr. Iris K. Aronson) C: Oral lichen planus (Reprint from Norman R, ed. Diagnosis of Aging Skin Diseases. London: Springer; 2008)

Figure 3.11 A: Lichen planus, lips* B: Lichen planus, palmoplantar* C: Lichen planus, genital* *Courtesy of Dr. Paul Getz

• Pruritic papular disease of skin and mucous membranes
• Due to cell-mediated autoimmune reaction toward basal layer keratinocytes; may be idiopathic, drug-related or infection-related (HCV)
• 4P’s: papular, pruritic, polygonal, purple
• Often lasts 1–2 years (except oral and hypertrophic forms, which typically have protracted courses)
• Presents with intense pruritus and violaceous, smooth flat-topped papules and plaques with fine scale (Wickham’s striae) over flexor wrists, forearms, legs, presacrum and other areas, + Köebner phenomenon
• No conclusive evidence to support association with autoimmune disease (per Bolognia); difficult to determine if true HLA association
• Histology
  • Hyperkeratosis (without parakeratosis)
  • ↑ Granular layer
  • Partially effaced rete ridges with widened papillae (‘sawtooth’ appearance)
  • Vacuolar change of basal layer with colloid bodies
  • B and-like lymphocytic infiltrate at dermoepidermal junction
  • Dermal melanophages
• Treatment: superpotent topical corticosteroids, topical calcineurin inhibitors, intralesional or systemic corticosteroid, phototherapy, methotrexate, acitretin, oral metronidazole (latter for erosive oral form)