Sézary syndrome (SS) is an aggressive form of cutaneous T-cell lymphoma with a diverse set of mutated genes. Using previously published datasets, we reanalyzed the copy number landscape of SS and detected whole genome amplifications in 20 % of all SS samples. Furthermore, we determined the molecular time of copy number occurrence and could show that single chromosome amplifications are extremely early events in the tumorigenesis. Contrastingly, whole genome duplications are extremely late events. Taken together, our results provide initial cornerstones for building a model of SS tumorigenesis based solely on genomic data.