Mycosis fungoides in a Mexican pediatric series: Clinical, immunophenotypic, and therapeutic features.

Background: Mycosis fungoides (MF) is a primary cutaneous lymphoma that in pediatric patients is frequently misdiagnosed as a benign dermatosis. Studies in Mexican children are limited. Objective: To describe the clinical, immunophenotypic, and therapeutic characteristics of MF in a Mexican pediatric series. Material and methods: It was conducted a cross-sectional study between 2017-2025 at a hospital in Mexico City, which included 17 pediatric patients younger than 18 years of both sexes with a diagnosis of MF. Results: They were 13 males and 4 females, with a mean age at diagnosis of 11.9 ± 2.8 years and a median disease duration of 3 years; 52.9% of patients were referred with a diagnosis of atopic dermatitis. The most frequent clinical variant was hypopigmented (64.7%). All cases were classified as stage IB. Diagnosis required a median of 2 biopsies, with delays of up to 12 months (range 3-24). All cases showed epidermotropism with CD3 and CD4 positivity (100%), and 88.2% showed CD8 positivity. All patients received topical corticosteroids; 3 received phototherapy, 3 methotrexate, and 3 photopheresis. The classic form of MF was associated with the presence of erythematous patches and erythematous scaly plaques, as well as, in some cases, with the use of methotrexate and phototherapy. Conclusions: Pediatric MF poses a diagnostic challenge due to its clinical similarity to common dermatoses. Although prognosis is generally favorable, its recurrence requires prolonged follow-up.