Skin-nontumor / Clinical dermatology
Other dermatoses
Lichen planus

Author: Mowafak Hamodat, M.D., MB.CH.B, MSc., FRCPC (see Authors page)

Revised: 1 July 2016, last major update August 2011

Copyright: (c) 2002-2016, PathologyOutlines.com, Inc.

PubMed Search: Lichen planus [title] skin

Definition / General
  • Purple, pruritic and polygonal papules of unknown origin
Clinical Features
  • Usually flexor arms and legs, glans penis and mucous membranes; may be confined to oral mucosa
  • Self-limiting, lasting 1 - 2 years, although longer for oral lesions
  • Rare in children in West, but more common in children in Asia and Middle East (Indian J Dermatol Venereol Leprol 2010;76:366)
  • May have zone of hyperpigmentation after resolution
  • May represent an abnormal, delayed hypersensitivity reaction to an unknown epidermal neoanatigen
  • Associated with hepatitis B and C, HIV, numerous drugs

  • Koebner phenomenon: new lesions at sites of trauma
  • Lichen planopilaris: primary site of involvement is the epithelium of hair follicles, causing alopecia
  • Wickham straie: white dots or lines within papules
  • Variants: atrophic, bullous, follicular, hypertrophic, pemphigoid and ulcerated
Clinical Images

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Lichen planus on the arm

Micro Description
  • Classic example of a lichenoid dermatitis
  • Hyperkeratosis and acanthosis; prominent, granular cell layer, sawtoothing of rete pegs, bandlike chronic inflammatory infiltrate (T cells and macrophages) that destroys the dermoepidermal junction
  • Civatte bodies (apoptotic basal cells, PAS+)
  • Artifactual cleft formation between epidermis and papillary dermis
  • Occasional subepidermal bullae
  • No atypia
Micro Images

Images hosted on PathOut servers:

Courtesy of Amy Lynn, M.D.

Positive Stains
  • Linear, fibrillar band of fibrin along dermoepidermal junction
  • The cytoid bodies may be highlighted by IgM, IgG, IgA and C3
Differential Diagnosis