Lichen Planus

Lichen Planus (LP)

Prevalence of 0.5%. F>M, but males usually affected earlier.

Cause unknown – viewed as autoimmune (t-cell mediated attack at epidermal-dermal cell junction) or a hypersensitivity reaction. Commonly associated with other autoimmune disorders (eg ulcerative colitis, diabetes mellitus)

Clinical features:
Characterised by multiple severely pruritic flat topped violaceous or purple shiny papules with fine white lines (Wickham’s striae) and scales; 1-5mm; distributed over flexor surfaces, wrist, forearm, leg, ankles, oral mucosa, genitalia, nails and scalp. Can affect just palms and soles.
Koebner reaction
Five P’s are characteristic of skin lesions – Plentiful, Pruritic, Polygonal, Polished, Purple, Papular, Planar
Nails – affected in 10-15% - thinning, longitudinal ridging, distal splitting

Mostly runs a course of 6 – 12 months and resolves

Specific patterns:
generalised – widespread, affecting most parts of body
follicular (lichen planopilaris) – small keratotic lesions involving scalp
localised – may become thickened and hypertrophic at any site
palm and sole – difficult diagnostic challenge (especially if other sites not affected); can resemble palmopustular psoriasis or one of the hereditary keratodermas; lesions tend to be sheet like rather than discrete – often hyperkeratotic and yellowish.
10% have nail dystrophy (“20-nail dystrophy”) – also get ridging, irregular pitting, splitting, loss of nail, pterygium formation

Topical corticosteroids

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