Epidemiological, Clinical, and Histopathological Features of Pediatric Pityriasis Lichenoides: A Retrospective Cohort With Long‐Term Follow‐Up

OBJECTIVE: Pityriasis lichenoides (PL) represents a spectrum of rare inflammatory skin disorders, including pityriasis lichenoides et varioliformis acuta (PLEVA), febrile ulceronecrotic Mucha-Habermann disease (FUMHD), pityriasis lichenoides chronica (PLC), and mixed-type variants. This study aimed to describe the epidemiologic, etiologic, clinical, and histopathologic features of pediatric PL in a tertiary referral center. METHODS: This retrospective study included 78 children diagnosed with PL between January 2003 and January 2017. Patients were followed for 3-7 years, with follow-up completed in 2024. Diagnosis was clinically suspected by a dermatologist and confirmed histopathologically. RESULTS: The mean age at diagnosis was 9.2 years; 59.0% were male. A preceding infection was documented in 60.3% of patients. Disease onset was most frequent in winter (44.9%) and spring (28.2%). Lesions were generalized in 65.4% of patients. PLC was the most common subtype (66.7%), followed by PLEVA (23.1%) and mixed type (10.3%). Histopathologic findings included basal vacuolar changes (88.5%), deep inflammatory infiltrates (83.6%), and parakeratosis (82.1%). Adnexotropism, folliculotropism, and syringotropism were less frequent than previously reported. During 2-7 years of follow-up, no patient developed mycosis fungoides. The most common treatments were azithromycin with topical corticosteroids (37.2%) and erythromycin with topical corticosteroids (30.8%). CONCLUSION: PL predominantly affects school-age children, shows a male predominance, and often presents in winter. PLC is the most frequent subtype. The absence of progression to mycosis fungoides during long-term follow-up supports the generally favorable prognosis of childhood PL and underscores the value of large pediatric cohorts with extended follow-up.