§ Blood staging for MF/SS is defined currently as B0 = <250/μL of CD4+/CD26− or CD4+/CD7− cells, B1= does not meet criteria for B0 or B2, and B2 = ≥1000/μL of CD4+/CD26−or CD4+/CD7−cells or other aberrant population of lymphocytes identified by flow cytometry. It is expected that patients with high blood tumor burden (B2) will have a clone in the blood that is identical to that in the skin. This evidence concerns the gene CD4 and neoplasm.