Blaschko-linear lichen planus of the face: A retrospective study of 6 cases and a literature review

Introduction and methods Different clinical and histological variants of lichen planus (LP) exist, such as lichen planopilaris, pigmentosus, linear, or atrophic LP. Recently, some cases came to our attention of hyperpigmented and atrophic linear lesions of the face with lichenoid histology, suggesting a combination of these different variants. We carried out a single-center, retrospective descriptive study of 6 similar cases selected from our database and compared them with a literature review. Results There were 4 males and 2 females of mean age 42 years. Each had linear lesions located on one side of the face. All lesions were initially itchy; they appeared hyperpigmented in all patients and atrophic in 5 cases. Biopsies indicated lichen planopilaris in 5 patients, with deep peri-eccrine involvement in 4 of them. Only 2 of the 6 patients had extra-facial lesions. Discussion and literature review We found 24 cases in the literature having similar clinical and histological aspects. Men aged around 37 years seemed particularly affected. An atrophic course was noticed in 10 patients. Such a clinicopathological picture may suggest differential diagnoses like lichen striatus, lupus erythematosus, lichen sclerosus atrophicus, or Moulin's linear atrophoderma. Early histopathological examination could be of precious assistance in allowing the initiation of effective treatment immediately as of the initial inflammatory phase, thereby limiting the risk of cosmetic sequelae such as atrophy or residual pigmentation. Conclusion We describe a form of facial lichen planus that is highly particular in terms of its follicular tropism, its blaschkoid distribution, its pigmented character, and its atrophic progression.