Morphologic identification of atypical chronic lymphocytic leukemia by digital microscopy

Introduction: Atypical chronic lymphocytic leukemia (aCLL) is a morphologic variant found in approximately 25% of patients with chronic lymphocytic leukemia (CLL). Although aCLL has a more aggressive course compared to typical CLL (tCLL), it is not usually reported. This retrospective study used digital microscopy to morphologically classify CLL patients as aCLL or tCLL, and determined the prevalence of prognostic markers in each group. Methods: CellaVision AB (Lund, Sweden) was used to evaluate lymphocyte morphology on archived blood films of 97 CLL patients, and results of their prognostic marker analysis at diagnosis were obtained. The unpaired t-test, Chi-square, or Fisher's Exact test were used for statistical analysis. Results: 27% of CLL cases were morphologically classified as aCLL. The aCLL group had a higher prevalence of trisomy 12, unmutated IgVH, and CD38 expression (markers associated with poor prognosis), and a lower prevalence of 13q14 deletions compared to tCLL; this was statistically significant. Conclusion: Using digital imaging to identify aCLL is feasible, economical, and may provide clinically relevant prognostic information at diagnosis and during periodic monitoring. Further study of a larger number of patients is needed to assess the clinical utility of reporting aCLL morphology.