In a separate prospective, hospital-based cohort study from Italy, similar in design to the Mayo Clinic study(19), Rossi et al.(27) compared the outcome of patients with MBL to individuals with Rai stage 0 CLL. In a consecutive series of 460 newly diagnosed cases with B-cell lymphocytosis of CLL phenotype, the authors used the IWCLL 2008 guidelines(26) to classify individuals as having either MBL or CLL (B-cell count < and ≥5 x109/L, respectively). The investigators identified 123 MBL cases and 337 CLL cases (Rai 0: 154; I–II: 129; III–IV: 54).
