CD4 and mycosis fungoides: Cutaneous T celllymphoma (CTCL) is a group of T cell malignancies that accumulate in the skin.The most common CTCLs are (1) the Mycosis fungoides (MF), which develops aspatches, plaques, or tumors containing apoptosis-resistant CD4+ CD45RO+ helper/memory T cells; and (2) the Sézary syndrome (SS), which is the leukemicform of CTCL that develops with erythroderma and the appearance of atypical Tcells in the peripheral blood [191].