dermatologic disorders
Pityriasis Lichenoides
Introduction
Pityriasis lichenoides is a clonal T-cell disorder that may develop in response to foreign antigens (eg, infections or substances) and may be associated with cutaneous T-cell lymphoma. Diagnosis is clinical. Treatment may include various topical and oral medications. Pityriasis lichenoides has distinct acute and chronic forms, which are usually distinct entities; however, lesions may evolve from the acute to the chronic form. 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. Lesions that appear erythematous on light skin may appear more violaceous (purple) or brown on dark skin. 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. 