<prompt> In wof Wickham;s striae are seenLichen nitidusLichen striatusLichen planusLichenoid eruption  <response>: Lichen Planus Pruritic papular disease of skin and mucous membranes Due to cell-mediated autoimmune reaction toward basal layer keratino-cytes; may be idiopathic, drug-related or infection-related HCV 4Ps: papular, pruritic, polygonal, purple Often lasts 1-2 years except oral and hyperophic forms, which typically have protracted courses Presents with intense pruritus and violaceous, smooth flat-topped papules and plaques with fine scale Wickhams striae over flexor wrists, forearms, legs, presacrum and other areas, Koebner phenomenon No conclusive evidence to suppo association with autoimmune disease per Bolognia; difficult to determine if true HLA association Histology:- Hyperkeratosis without parakeratosis Granular layer Paially effaced rete ridges with widened papillae sawtooth appearance Vacuolar change of basal layer with colloid bodies Band-like lymphocytic infiltrate at dermoepidemal junction Dermal melanophages Treatment:- superpotent topical coicosteroids, topical calcineurin inhibi tors, intralesional or systemic coicosteroid, phototherapy, methotrexate, acitretin, metronidazole latter for erosive oral form. Ref:- Sima Jain; pg num:- 106,108 