CD4 and skin neoplasm: Previously, we reported that G17V RHOA mutations were detected by flow cytometry only in CD4-positive (CD4+) cells but not in other cell lineages purified from the skin tumor of a PTCL-NOS patient and the pleural effusion cells of an AITL patient.8 These preliminary results suggested that the G17V RHOA mutation may specifically exist in mature CD4+ T cells in PTCL-NOS and AITL.