The Clinical Significance of Large Cells in Bone Marrow in Patients with Chronic Lymphocytic Leukemia

BACKGROUND. Patients with chronic lymphocytic leukemia (CLL) that transforms to Richter syndrome (RS) frequently show atypical lymphocytes in bone marrow; however, a diagnosis of RS requires confirmation of the presence of sheets of large cells in bone marrow or lymph nodes. METHODS. In this study, the authors evaluated the clinical significance of scattered large cells in bone marrow. They assessed the possibility of predicting transformation to RS in bone marrow smears by counting the percentages of prolymphocytes and large cells in 78 patients with CLL and 29 patients with lymph node biopsy-confirmed RS. RESULTS. The percentage of large cells was found to be correlated with decreasing survival in a continuous fashion (P = 0.006). It is interesting to note that patients who had > 7% large cells in the bone marrow and elevated β₂-microglobulin (β₂-K levels (> 5 mg/L) had a survival duration identical to that of patients with RS, and these factors together were a strong predictor of RS (P < 0.001). CONCLUSIONS. Patients with CLL who had bone marrow that contained > 7% large cells and who had β₂-M levels > 5 mg/L had a disease that was similar to RS, and the combination of large cells and β₂-M can be used as a surrogate marker for RS.