active infections Referral to a dermatologist is recommended to institute longer-term treatment as needed Pityriasis lichenoides Pityriasis lichenoides is a lymphocytic inflammatory skin condition that classically has been divided into the acute (pityriasis lichenoides et varioliformis acuta or PLEVA) form and the chronic (pityriasis lichenoides chronica or PLC) form This distinction may be artificial as there are often overlapping features of both in an individual patient so the term pityriasis lichenoides (PL) is generally preferred There is a rare and severe form known as febrile ulceronecrotic Mucha–Habermann (FUMH) syndrome Patients present with persistent crops of skin lesions that vary in appearance from crusted vesicles and papules ( Fig 70.9 ) to scaly patches and small plaques that may be hypopigmented in some cases ( Fig 70.10 ) These lesions are most often asymptomatic There is often a predilection for sun-protected areas, and in summertime, areas exposed to sunlight often show fewer skin lesions In FUMH syndrome, these lesions are often accompanied by fever and larger, often painful, ulcerated papules and plaques At times, the condition may be initially misdiagnosed as varicella, but PL patients are generally afebrile (except in FUMH), and the lesions of PL persist for months to years At other times, the condition may resemble PR but PL will persist for months to years, differentiating it from PR Infants who develop crusted papular eruptions that resemble PL should also be evaluated for the possibility of LCH