Mycosis Fungoides in Paediatric Patients: A Real‐Life Retrospective Study

ABSTRACT Background Mycosis fungoides (MF) is the most common type of cutaneous T cell lymphoma, and less than 5% of cases occur in paediatric patients. No treatment standardized guidelines exist for paediatric population, and evidence comes from small retrospective studies. No studies in Mexican children were identified. Objectives To describe epidemiological data, to determine treatment response and factors associated with remission or relapse, and to examine the impact of diagnosis delay in complete remission. Methods We retrospectively analysed records of all patients aged 0−18 years diagnosed with MF who were treated in Centro Dermatológico Pascua, between January 2007 and July 2023. Results One hundred and twenty‐three patients were included. The median age at diagnosis was 12 years. All patients presented with early clinical stages (IA/IB). Hypopigmented phenotype was present in 70.7%. Phototherapy was the most frequently indicated treatment (89.4%). Complete remission was achieved by 35.8% in a median of 16.54 ± 14.74 months. Involved body surface area (BSA), duration of disease and phototherapy were inversely associated with complete remission. The median time to follow‐up was 19 months (range 40 months), with an overall survival of 100%, and no disease progression. Relapse was present in 15.44%, and associated predictors were skin phototype and clinical variants different from hypopigmented. BSA and the duration of the disease were negatively associated. Institutional diagnosis delay had a median of 3 months (range 0.8−10.7 months), with no statistically significant impact in complete remission. Conclusions To our knowledge, this study represents the largest paediatric cohort worldwide, and the first to examine the Mexican population. Phototherapy is the most prescribed treatment modality in our centre, with acceptable remission rates. Our study confirms a favourable prognosis of MF in children. Prospective studies are needed to better characterize the epidemiology and clinical course of the disease, to determine treatment efficacy and to identify prognostic factors.