LAUSR

EJD, vol. 32, n◦ 3, May-June 2022 escape mechanism in SS [7]. Furthermore, the receptor for CCL3 and CCR4 is found on tumour cells and regulatory T cells and is particularly involved in the development of SS [7, 8]. Finally, the observed decrease in CXCL10 could be responsible for the loss of Sézary cell epidermotropism and their consequential presence in the blood [8, 9]. Inhibition of one immune pathway may result in an imbalance in cytokine production and cause, in susceptible patients, paradoxical activation of other immune pathways responsible for inflammatory or neoplastic processes. Dedicated studies are needed to establish a causal link between IL-5 inhibition and the immunological alterations that may have contributed to the development of SS in our patient. Our observation is proof of the need for caution regarding the use of rapidly emerging cytokine pathway inhibitors, the immunological consequences of which remain poorly understood.