Pityriasis lichenoides
Summary
Definition
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][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].
History and exam
Key diagnostic factors
- acute to subacute recurrent skin eruption
- polymorphic, generalised, non-pruritic skin eruption
Other diagnostic factors
- scars or pigment changes
- immunosuppression
- recent illness
- family history of pityriasis lichenoides
- headache
- myalgias/arthralgias
- malaise
- burning/pruritus
- multi-organ failure
Risk factors
- childhood to early adult age
- male sex
- HIV
Diagnostic investigations
1st investigations to order
- dermoscopy
- skin biopsy
Investigations to consider
- anti-streptolysin titres
- Epstein-Barr virus IgM/IgG viral capsid antigen and nuclear antigen antibody
- monospot or heterophil antibody test
- hepatitis B surface antigen, anti-surface antibody, and anti-core IgM
- hepatitis C virus antibody
- HIV screening
- rapid plasma reagin
- throat cultures
- toxoplasma Sabin-Feldman's dye test, indirect immunofluorescence/haemagglutination
- erythrocyte sedimentation rate
- CRP
- serum LDH
- WBC count
- serum albumin
Treatment algorithm
mild to moderate disease
severe disease or treatment resistance
Contributors
Authors
Amor Khachemoune, MD, CWS
Clinical Instructor in Dermatology
SUNY Downstate Medical Center
Brooklyn
NY
Disclosures
AK declares that he has no competing interests.
Marianna Blyumin-Karasik, MD
Dermatology Faculty
Department of Dermatology & Cutaneous Surgery
University of Miami
Miami
FL
Disclosures
MB-K declares that she has no competing interests.
Peer reviewers
Andrew D. Lee, MD
Resident
Department of Dermatology
Wake Forest University School of Medicine
Winston-Salem
NC
Disclosures
ADL declares that he has no competing interests.
Abdulhafez Selim, MD
Assistant Professor
King Fahd University of Petroleum and Minerals
Dhahran
Saudi Arabia
Disclosures
AS declares that he has no competing interests.
Differentials
- Lymphomatoid papulosis
- Guttate psoriasis
- Drug eruption
More DifferentialsPatient leaflets
Psoriasis
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