Yael Renert-Yuval 1 2, Hadas Prag Naveh 2 3, Ofer Reiter 2 3, Yael Shahal-Zimra 4, Itay Pickholtz 4, Dan Ben Amitai 1 2, Rivka Friedland 1 2, Emmilia Hodak 2 5
Flow cytometry is a standard tool for blood involvement classification in mycosis fungoides (MF). However, data are lacking for paediatric patients, who primarily exhibit early-stage disease. We retrospectively analysed flow cytometry results from 65 paediatric patients with early-stage MF. All were classified as B0 or B1, indicating no or low-level blood involvement, respectively. None met the B2 criteria. B1 rates were 34% and 49%, based on percentage and absolute count criteria of CD4+/CD7- or CD4+/CD26-, respectively. These rates are markedly higher than previously reported for adult MF. B status was not correlated with demographic or clinical findings. During a mean (SD) follow-up of 5.6 (4.0) years, none of the patients had stage progression. Our cohort’s frequent B1 classification in early-stage paediatric MF suggests that a reassessment of the criteria defining B0 and B1 may be necessary. Furthermore, considering the benign course of paediatric MF, the clinical significance of B status assessment warrants further investigation.