Pityriasis lichenoides

A rare inflammatory skin disease with unclear aetiology.

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, categorise, 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's disease.[1]Khachemoune A, Blyumin ML. Pityriasis lichenoides: pathophysiology, classification, and treatment review. Am J Clin Dermatol. 2007;8(1):29-36. http://www.ncbi.nlm.nih.gov/pubmed/17298104?tool=bestpractice.com [Figure caption and citation for the preceding image starts]: Acute form of pityriasis lichenoides on the trunk and arm of a young boyFrom the collection of Dr A. Khachemoune, SUNY Downstate Medical Center, Brooklyn. [Citation ends].