Shortly after, Dorfman & Shahsafaei studied by means of flow cytometry bone marrow and lymph node aspirates from patients with different mature B cell lymphoid neoplasms, showing that CLL and HCL cases were all CD200 positive, prolymphocytic leukemia (PLL) were positive in 80% of cases, while MCL, splenic marginal zone lymphoma (SMZL), and follicular lymphoma (FL) were all negative (32). This evidence concerns the gene CD200 and hairy cell leukemia.