Pathologic and Molecular Genetic Features of Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) is an indolent B-cell leukemia. While many patients may not require therapy, some patients will suffer a progressive course and die of their disease. This clinical heterogeneity is reflected in the molecular genetic heterogeneity that is becoming apparent through studies of immunoglobulin heavy chain gene mutational status, chromosomal numerical abnormalities, microRNA abnormalities, and genetic abnormalities identified by whole genome sequencing. Indeed, many of these studies are becoming routine in the assessment of patients with CLL or being incorporated into clinical trials to further stratify patients for appropriate therapies. Here, we will review the morphologic, immunophenotypic, and molecular genetic features of CLL and touch upon the concept of monoclonal B-cell lymphocytosis.