A rare inflammatory skin disease with unclear etiology.
It manifests as widespread polymorphic papulosquamous dermatitis that varies in a spectrum of clinical presentations and course. The course of pityriasis lichenoides is unpredictable.
Very rarely, it may progress to the cutaneous form of lymphoma.
It is optimally managed with a combination of topical, light, and systemic therapies.
Pityriasis lichenoides is an uncommon, acquired, idiopathic skin condition. It is a challenging disorder to diagnose, categorize, and treat due to its varied presentation and uncertain course. Pityriasis lichenoides manifests as diffuse polymorphic, papulosquamous dermatitis that varies in severity, temporal onset and development, and prognosis. The scope of presentations is classified along a continuum of 3 subtypes, including pityriasis lichenoides et varioliformis acuta, pityriasis lichenoides chronica, and febrile ulceronecrotic Mucha-Habermann disease. 
Clinical Instructor in Dermatology
SUNY Downstate Medical Center
AK declares that he has no competing interests.
Department of Dermatology & Cutaneous Surgery
University of Miami
MB-K declares that she has no competing interests.
Department of Dermatology
Wake Forest University School of Medicine
ADL declares that he has no competing interests.
King Fahd University of Petroleum and Minerals
AS declares that he has no competing interests.
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