<prompt> False about Lichen planus isFound in skin except mucosaPapule is purple colouredInvolves basal layer of skinShows hyperkeratosis  <response>: A Found in skin except mucosa LICHEN PLANUS: Common disorder, usually of middle aged, who present with an irritating rash affecting flexures of wrist forearms, trunk ankles with an unknown etiology Important features are severe itching and oral involvement 5 Ps of Lichen Planus are Pruritic, Purple, Polygonal, Flat top, Papular lesion Rash consists of discrete purple, shiny polygonal papules with fine white lines passing through them Wickham striae often occurring in scratch marks other sites of injury Koebners phenomenon. Hypopigmentation In residual disease is not seen Pterygium of nail hypertrophy of eponychium is important feature 10 Histopathology shows hyperkeratosis, irregular acanthosis, band like dermal infiltrate of lymphocyte adjacent to the epidermis damage to the epidermal basal cells. Dermis infiltrates with T-cells Civatte bodiesColloid bodies necrotic keratinocytes in dermis are seen. Usually resolves within 6 months but recurrences may occur, resolve in 9-18 months. Main histological features of LP is Basal cell degeneration, Civatte bodies, Max Josephs space - Melanin incontinence; Others - Mononuclear infiltration of upper dermis. 