A 6-year-old presents with this diffuse rash, a low-grade fever and malaise.

PITYRIASIS LICHENOIDES AND PLEVA

Pityriasis lichenoides (PL) is a skin condition that manifests in either the acute (pityriasis lichenoides et varioliformis acuta or PLEVA) or the chronic form (pityriasis lichenoides chronica or PLC).

• The age of onset is from 1 year to old age, although it is most common in the first 3 decades.
• In one study, the average age of patients with PLEVA was 6.5 years.
  
• The disease may last from months to decades, often with lesions coming in crops.
• Evidence for viral involvement has included coexistent influenza, EBV acutely elevated titers, associated infectious mononucleosis, adenovirus isolated from the urine, a measles vaccine (live attenuated) 5 days prior, and herpes zoster infection 2 weeks prior.
• Some cases have been found to have atypical CD 30+ cells. Spontaneous resolution may mean the immune system eliminated this clone. Progression to lymphoma may mean that this clone progressed.
• Two children with lesions similar to pityriasis lichenoides have developed lymphoma. Another report describes 3 children with CTCL that resembled pityriasis lichenoides.

Clinical

Multiple, disseminated, red, scaly papules and hemorrhagic necrotic lesions are characteristic. They are widespread but are often concentrated on the lower trunk and buttocks. Fever and constitutional symptoms may accompany the outbreaks.

Differential Diagnosis

Always consider secondary syphilis which can look nearly identical.

Treatment of Acute Cases

• Observation
• Oral erythromycin
• 3 courses of azithromycin over 6 weeks and refer for phototherapy
• UVB
• Dupilumab for chronic cases

PLEVA usually follows a benign course and treatment is not necessary, especially if the lesions are asymptomatic. Getting some sun may help clear the lesions. For those that need treatment, erythromycin for 2-4 months is often prescribed for children. Alternatively, a tetracycline may be given for older children or adults. Topical steroids have a place, but the diffuse nature of the condition and the lack of tremendous efficacy limits their use. Phototherapy, be it narrow band or broadband UVB or PUVA, is usually quite effective.

Monitoring in Chronic Cases

Patients with prolonged disease should always be monitored for progression to lymphoma, most commonly CTCL. Indeed, routine biopsy (e.g. every year) is reasonable. Patients at higher risk for progression to lymphoma are those with prolonged doses duration (e.g., > 5 years), changing morphology (e.g. to nodules, hypopigmentation, atrophy or poikiloderma), and localization to sun-protected areas.

Additional Pictures

RegionalDerm

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