Acute Onset Linear Lichen Planus Pigmentosus of the Forehead: A Case Series

Linear lichen planus pigmentosus (LPP) of the face is a rare variant of lichen planus, with only a few cases published in the literature.1 It is an inflammatory condition with unknown etiology, characterized by blue-gray hyperpigmented macules, and tends to affect sun-exposed areas of the head and neck.1-4 The pathophysiology of linear lichen pigmentosus is poorly understood, though it is postulated to be caused by T-lymphocyte autoimmunity against keratinocytes.5-7 LPP more frequently affects middle age woman and skin phototypes III-VI.1,3 Treatment for linear LPP is difficult and there is no established first-line therapy; however, tacrolimus ointment, topical corticosteroids, and various systemic agents have shown to be effective in improving the appearance.3,8,9 Prior reports have characterized linear LPP that follows the lines of Blashko as more commonly affecting the trunk.1 We present three cases of linear lichen planus pigmentosus (LPP) of the forehead, a unique novel presentation of linear LPP of the face. One of our cases also provides supporting evidence for tacrolimus to be used as a preferred therapy to treat linear LPP of the face; however, more research is needed to support this claim. To our knowledge, this case series is the largest case series of linear lichen planus pigmentosus (LPP) of the forehead to be reported. J Drugs Dermatol. 2023;22(1):94-97. doi:10.36849/JDD.7200.