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Pityriasis Lichenoides


Shinjita Das

, MD, Harvard Medical School

Last full review/revision Apr 2020| Content last modified Apr 2020
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Pityriasis lichenoides is a clonal T-cell disorder that may develop in response to foreign antigens (eg, infections or drugs) and may be associated with cutaneous T-cell lymphoma. Treatment may include various topical and oral drugs.

Pityriasis lichenoides has distinct acute and chronic forms, which are usually distinct entities; however, lesions may evolve from the acute to chronic type. The acute form typically appears in children and young adults, with crops of asymptomatic chickenpox-like lesions that typically resolve, often with scarring, within weeks to months. Antibiotics (eg, tetracycline, erythromycin) or phototherapy may help.

The chronic form of pityriasis lichenoides initially manifests as flatter, reddish brown, scaling papules that may take months or longer to resolve.

Diagnosis of Pityriasis Lichenoides

  • Clinical evaluation

  • Sometimes biopsy

Diagnosis of pityriasis lichenoides is based on clinical appearance and distribution.

Biopsy is done when clinical findings are inconclusive.

Differential diagnosis of pityriasis lichenoides includes the following:

Treatment of Pityriasis Lichenoides

  • Various topical and oral treatments

Treatment of pityriasis lichenoides is often ineffective, but sunlight, topical corticosteroids, topical tacrolimus, oral antibiotics, phototherapy, and immunosuppressants have been used with varying success (1).

Treatment reference

  • 1. Bowers S, Warshaw EM: Pityriasis lichenoides and its subtypes. J Am Acad Dermatol 55:557–572, 2006. doi: 10.1016/j.jaad.2005.07.058.

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