High prevalence of adverse prognostic genetic aberrations and unmutated IGHV genes in small lymphocytic lymphoma as compared to chronic lymphocytic leukemia

摘要

According to the WHO classification, chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL) are considered the same entity. However, the clinical presentations are different. As yet, detailed molecular–genetic comparisons between CLL and SLL are scarce. In this study, we evaluated the presence of genetic abnormalities and (immunoglobulin heavy chain variable genes) IGHV use and mutation status in lymph node samples of patients presenting with lymphadenopathy alone and, therefore, classified as SLL (n = 21) or with persisting lymphadenopathy and absolute lymphocyte counts of ≥5 × 109/L and, therefore, classified as CLL/SLL (n = 17). In addition, blood samples of CLL patients were evaluated (n = 82). The majority of lymph node samples from SLL patients (66%) showed unmutated IGHV genes. This occurrence was significantly higher than in CLL (29%). Poor risk genetic aberrations (11q-, 17p-, and +12) were more prevalent in the SLL (45%) as compared to CLL (22%). Samples from CLL/SLL patients exhibited almost equal frequencies of poor risk genetic aberrations (53%), but lower frequencies of unmutated IGHV genes (35%), as compared to SLL. In summary, SLL not only differs clinically from CLL, but also genetically, with a higher propensity of adverse molecular parameters in SLL. CLL and SLL likely encompass a phenotypic spectrum within one disease entity.