The clinical and laboratory findings in pediatric mycosis fungoides- Can elevated blood eosinophil levels be related to the type of mycosis fungoides?

Mycosis fungoides (MF) is the most common type of cutaneous T-cell lymphoma, however; it is rare in children. MF may mimick AD with laboratory findings such as elevated blood eosinophil levels and high immunoglobulin E (IgE) levels. Previous studies have demonsrated a positive correlation between the eosinophil levels and the advanced stage of adult MF. We aim to investigate the clinical presentation, treatment modalities and responses in pediatric MF patients and compare the laboratory parameters of children with MF with the healthy controls. A total of 29 pediatric MF patients and 29 healthy controls, were included. All patients were diagnosed with stage IA. Hypopigmented MF was the most common variant (62.06%), followed by folliculotropic (27.58%). Narrow band-UVB was the most commonly treatment method. LDH was significantly higher in the patient group MF patients (p =0.001). There was a significant difference in frequency of patients with elevated blood eosinophil levels according to MF type (p =0.013), elevated eosinophil levels was found in 66.7% of hyperpigmented MF, 37.5% of folliculotropic MF, and 6.7% of hypopigmented MF. Elevated blood eosinophil levels, which we found more frequently in children with MF than in healthy individuals in our study, is not clear if it is related with the prognosis or disease severity in pediatric MF patients. In our study, the MF type with the lowest frequency of patients with elevated blood eosinophil levels was hypopigmented. We assume that the elevated blood eosinophil levels in children is also associated with MF as in adult patients. However, the relationship between elevated blood eosinophil levels, which is suggested to be a poor prognosis indicator in adults, and prognosis of childhood MF is unknown, and prospective studies are needed on childhood MF.