Lymphomatoid papulosis in children: a series of 25 cases

Background Lymphomatoid papulosis (LyP) is an uncommon cutaneous T-cell lymphoproliferative disorder (CTLPD) rarely encountered in children. Objectives To specify characteristics of paediatric LyP and to describe both diagnostic difficulties and the course of the disease with the experience of 10 years' follow-up. Methods This was a retrospective, single-centre study of 25 children diagnosed with LyP according to the 2008 World Health Organization guidelines, and a clinical and pathological correlation by two experts. Results The mean age at onset was 7.5 years. The lesions were mostly papulonodular with frequent pruritus (40%). Mucosal involvement was sometimes observed. A single ulcerative nodule was initially suggestive of a primary cutaneous anaplastic large-cell lymphoma (C-ALCL). Pityriasis lichenoides was associated in 36% of cases, atopic dermatitis in 28% and nonspecific infections in 28%. Complete remission was observed in 44% of cases. Through the mean follow-up of 10 years, none of our patients have experienced lymphoma occurrence. Histopathological subtype A clearly predominated (82%). A marked eosinophilic infiltrate was present in 44% of cases and a cutaneous T-gamma clone in 40%. No correlation was observed between histopathological subtype, cutaneous clone or LyP clinical course. Conclusions Paediatric LyP belongs to the group of CD30-positive CTLPDs including C-ALCL. Children have to be carefully followed up lifelong, even if the prognosis appears good. The high frequencies of an associated viral infection, atopic dermatitis, marked eosinophilic infiltrate and a good outcome suggest that paediatric LyP could be considered a reactional disease rather than a malignant disorder.