Pityriasis lichenoides: Long-term follow-up study

Background/objectives Pityriasis lichenoides is an uncommon papulosquamous disorder of unknown etiology. The objective of this study was to review the clinical features and treatment responses of individuals with pityriasis lichenoides seen at a tertiary referral center. Methods Seventy-five patients diagnosed with pityriasis lichenoides between 1997 and 2013 were reviewed, and 46 had long-term follow-up via telephone interviews. Results Fifty (67%) patients were diagnosed with pityriasis lichenoides chronica, 22 (29%) with pityriasis lichenoides et varioliformis acuta, and 3 (4%) with mixed pityriasis lichenoides chronica and pityriasis lichenoides et varioliformis acuta features. Mean ± standard deviation age at onset was 12 ± 13 years (median 8 years). Disease duration was significantly shorter for patients with pityriasis lichenoides et varioliformis acuta (35 ± 35 months) than for those with pityriasis lichenoides chronica (at least 78 ± 48 months). At long-term follow-up, 23 of 28 (82%) patients with pityriasis lichenoides chronica and 3 of 16 (19%) with pityriasis lichenoides et varioliformis acuta had active disease. None progressed to lymphomatoid papulosis or cutaneous T-cell lymphoma. Ten of 23 active pityriasis lichenoides chronica cases had residual pigmentary change independent of race and lasted at least 35 ± 20 months. The most effective treatments were phototherapy (47% response rate), heliotherapy (33%), topical corticosteroids (27%), and antibiotics (25%). Conclusion Pityriasis lichenoides is a predominantly pediatric disorder. The time course of pityriasis lichenoides chronica is significantly longer than that of pityriasis lichenoides et varioliformis acuta. Pityriasis lichenoides chronica may persist with pigmentary alterations in the absence of other signs of active inflammation. Treatment response is often limited, particularly for patients with pityriasis lichenoides chronica.