Systematic review of the efficacies and adverse effects of treatments for pityriasis lichenoides.

BACKGROUND: Pityriasis lichenoides (PL) is a papulosquamous dermatosis affecting both children and adults, for which no standard treatment currently exists.

OBJECTIVES: To characterize different treatment options and develop an evidence-based treatment algorithm for PL.

METHODS: A systematic search of published literature on PL treatments was performed on 23 December 2017 via the MEDLINE, Embase, CINAHL, CENTRAL, ClinicalTrials.gov and the EU Clinical Trials Register databases.

RESULTS: Of 1090 abstracts retrieved, 27 full-text articles with 502 participants were included for analysis. Seventeen of the full-text articles were retrospective cohort studies and two were randomized controlled studies. Treatment modalities included in these articles were phototherapy, antibiotics, methotrexate, pyrimethamine and trisulfapyrimidine, corticosteroids and conservative treatment. Of these treatments, phototherapy led to complete remission in the highest proportion of patients, and topical corticosteroids were found to have been trialled in the highest number of patients.

CONCLUSIONS: The current literature consists almost entirely of uncontrolled studies, and none provides compelling data to support an evidence-based approach to PL treatment. Pityriasis lichenoides chronica and pityriasis lichenoides et varioliformis acuta should be distinguished in response to treatment, and definitions of response to treatment must be standardized. Additional randomized control studies with longer follow-up will help better differentiate between treatment efficacies and adverse effects.