In 2019, Anzengruber et al., showed that the SS malignant T-cells did not demonstrate extreme differences in the expression levels of CTLA-4 between the tumor, non-tumor cells, and healthy controls [91] which was in contrast with previous studies displaying that CTLA-4 was upregulated in MF and SS patients and correlates with disease progression [90, 92]. Here, CTLA4 is linked to synovial sarcoma.