Pityriasis Lichenoides : Anatomo-clinical Aspects and Follow-up

Introduction: Pityriasis lichenoides (PL) is an inflammatory dermatitis of undetermined origin consisting of specific papular lesions reflecting an "indolent" lymphoproliferative state. The current classification is confusing because it mixes semiological and chronological notions. The objectives of this study are to better describe the clinical, epidemiological, histological, phenotypic and evolutionary aspects of PL in an adult population. Methods: Investigators will perform a retrospective cohort study including patients with clinical and histological diagnosis of PL from the coding of the Department of Pathology of Henri-Mondor Hospital and from medical records and photographs of lesions if available, between January 2012 and August 2018. A follow-up telephone interviews will also be proposed to each patient to collect evolution data. Photographs will be systematically reviewed as well as cutaneous samples and a genomic analysis will be performed. Conclusion: Investigators would like to better understand clinical, histological features and evolutionary aspects of PL in an adult population.