Paediatric Mycosis Fungoides: Clinical Variants, Treatment Modalities and Response to Therapy

Mycosis fungoides is a rare cutaneous lymphoma in the paediatric population. The aim of this study was to examine the epidemiological, clinical, and histological characteristics, as well as the treatment modalities and response to therapy of paediatric patients with mycosis fungoides. This retrospective cohort study reviewed the records of 37 paediatric patients treated at Rambam Medical Center, Israel, between 2013 and 2021. Extracted data included epidemiology, clinical presentation, histological reports, infiltrate clonality status, treatment modalities and response to therapy. The mean follow-up period was 60 months. All patients were diagnosed with stage IA or IB disease. Folliculotropic mycosis fungoides was the most prevalent variant (49%). Most patients were treated with phototherapy (90%), with a response rate of 85%, and a complete response rate of 55% after the first course. There were no significant differences in response to phototherapy between the folliculotropic or other variants (p = 0.072). Similarly, delayed diagnosis, atopic diathesis, clonality, phototherapy type or number of treatments, were not associated with response to therapy, while protracted phototherapy was associated with prolonged remission. In conclusion, mycosis fungoides in the paediatric population is an indolent disease with a favourable prognosis and potentially prolonged response to phototherapy. SIGNIFICANCE Mycosis fungoides is the most cutaneous T cell lymphoma in general population. In children, mycosis fungoides is an indolent disease with overall good prognosis. This study analysed data for a cohort of 37 paediatric patients for a long follow-up period. The results show that the folliculotropic variant is more common than previously thought. In addition, the results showed that initial treatment with narrowband ultraviolet B phototherapy can be considered for paediatric patients with folliculotropic mycosis fungoides, especially if the lymphocytic infiltrate is superficial.