TY - CHAP M1 - Book, Section TI - Lichen Planus A1 - Mangold, Aaron R. A1 - Pittelkow, Mark R. A2 - Kang, Sewon A2 - Amagai, Masayuki A2 - Bruckner, Anna L. A2 - Enk, Alexander H. A2 - Margolis, David J. A2 - McMichael, Amy J. A2 - Orringer, Jeffrey S. PY - 2019 T2 - Fitzpatrick's Dermatology, 9e AB - AT-A-GLANCELichen planus is an idiopathic T cell–mediated process without a clear autoantigen.The worldwide prevalence of lichen planus is approximately 1%.The lesions are well-marginated, flat-topped, red-violet polygonal papules.The distribution is symmetrical and grouped lesions affect the flexural aspects of the arms and legs.Variants are based on configuration, morphology of lesion, and site of involvement.Histology shows basal keratinocyte damage with a lymphocyte-rich interface reaction. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - accessmedicine.mhmedical.com/content.aspx?aid=1162812968 ER -