Typical Sézary cells have a CD3<sup>+</sup>CD4<sup>+</sup>CD8<sup>-</sup> phenotype; however, in cases of the aberrant loss of antigens on Sézary cells, especially the loss of critically important T-cell antigens such as CD4, there is a possibility of misdiagnosing the disease or underestimating the tumor burden of the disease. The gene discussed is CD8A; the disease is neoplasm.