Skin nontumor
Lichenoid and interface reaction patterns
Lichen planus

Topic Completed: 1 August 2011

Minor changes: 5 October 2020

Copyright: 2002-2020,, Inc.

PubMed Search: Lichen planus [title] skin "loattrfree full text"[sb]

Mowafak Hamodat, M.B.Ch.B., M.Sc.
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Cite this page: Hamodat M. Lichen planus. website. Accessed October 20th, 2020.
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

Microscopic (histologic) 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
Microscopic (histologic) images

Contributed by
Hillary Rose Elwood, M.D.

Band-like lichenoid lymphocytic infiltrate with irregular saw tooth rete ridge, hypergranulosis and hyperkeratosis

 Contributed by
 Andrey Bychkov, M.D., Ph.D.

Lymphocytic band

 Contributed by
 Amy Lynn, M.D.

Various images

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