Relevance of IgVH gene somatic hypermutation and interphase cytogenetics in lymphomatous presentation of chronic lymphocytic leukemia/small lymphocytic lymphoma

Background. Chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL) are regarded as the same entity, with SLL restricted to tissue cases featuring no leukemic phase. In this study, the authors evaluate a group of SLL cases for cytogenetic abnormalities and IgVH gene mutational status to illicit differences between CLL and SLL. Design. IgVH gene polymerase chain reaction amplification and subsequent sequencing were preformed on formalin-fixed, paraffin-embedded archival tissue of 44 patients (SLL n = 34 or CLL n = 10). Cytogenetic data, CD38, and ZAP-70 expression were also evaluated for these cases. Results. The data indicate that 9/34 (26%) SLL cases have somatic hypermutation >2%, which is less than the CLL group where 40% were mutated (4/10). Cytogenetic abnormalities were seen in 58% of the SLL cases with many showing abnormalities associated with favorable to intermediate prognosis. Conclusion. The authors' attempt to compare CLL with SLL with regards to cytogenetic and IgVH mutational status shows no statistically significant difference.