Although less recurrent genetic imbalances such as MYC gain (40%) and MNT loss (30%) together with variable genomic or epigenetic criteria have been proposed to differentiate SS from erythrodermic inflammatory dermatoses [4, 49], our study is original in supporting the introduction of a simple and robust TP53 testing in algorithms for the diagnosis of patients with erythroderma as well as for leukemic assessment in patients with CTCL. The gene discussed is TP53; the disease is synovial sarcoma.