Skin-nontumor - Lichen planus

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Skin-nontumor

Other dermatoses

Lichen planus

Reviewer: Mowafak Hamodat MB.CH.B, MSc., FRCPC (see Reviewers page)
Revised: 5 September 2011, last major update August 2011
Copyright: (c) 2002-2011, PathologyOutlines.com, Inc.

Definition
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● Purple, pruritic and polygonal papules of unknown origin

Clinical features
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● 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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Various images

Micro description
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● 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
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Various images

Contributed by Dr. Amy Lynn, Toledo, Ohio

Virtual slides
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Lichen planus

Positive stains
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● 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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● Lichenoid keratosis
● Poikiloderma
● Chronic discoid lupus
● Lichenoid drug reaction

End of Skin-nontumor > Other dermatoses > Lichen planus

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