Clinicopathologic Characteristics, Treatment Outcomes of Pediatric Mycosis Fungoides in Turkey: A National Multicenter Retrospective Cohort.

Background

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Objectives

This study aimed to characterize the clinical spectrum, diagnostic delay, treatment patterns, and outcomes of pediatric mycosis fungoides (MF) and to identify predictors of early response.

Methods

This national multicenter retrospective study included patients diagnosed with histopathologically confirmed MF before 18 years of age. Demographic, clinical, histopathologic, immunophenotypic, staging, treatment, and follow-up data were collected. Early response at 3-6 months (partial/complete response) was analyzed using logistic regression.

Results

A total of 133 patients were included; 60.9% (81/133) were male. Median age at diagnosis was 13 years (IQR, 9-15) and median diagnostic delay was 18 months (IQR, 8-48). Classic morphology was recorded in 78.2% (104/133), and hypopigmented MF in 36.1% (48/133); overlapping morphologies were documented in 42.1% (56/133). Stage IA disease was present in 59.4% (79/133). Phototherapy was used in 60.9% (81/133). Early response occurred in 91.0% (121/133). BSA < 10% was independently associated with higher odds of early response (aOR 8.42, 95% CI 1.71-41.54; p = 0.009), whereas older age at diagnosis predicted lower odds (aOR 0.81 per year, 95% CI 0.67-0.98; p = 0.029). Relapse occurred in 28.5% (37/130) within median follow-up of 22 months (median time to relapse of 8 months); 67.6% (25/37) relapsed within 12 months.

Conclusion

In this cohort, pediatric MF presented at an early stage. Despite favorable early responses, relapse occurred in nearly one third, often within the first year, supporting long-term surveillance. Higher BSA involvement and older age at diagnosis were associated with reduced early response.