Smudge cell percentage as a surrogate marker for ZAP-70 expression in patients with chronic lymphocytic leukemia.

Background: This study aimed to evaluate the prognostic value of smudge cell percentage as a surrogate marker for zeta-chain-associated protein kinase 70 (ZAP-70) expression in chronic lymphocytic leukemia (CLL) patients.

Methods: Sixty three newly diagnosed CLL patients were investigated at the Hematology Department of the Medical Research Institute of Alexandria University with complete blood count, lactate dehydrogenase, β2 microglobulin levels, ZAP-70 expression, and estimation of the percentage of smudge cells.

Results: The percentage of smudge cells ranged from 2 to 58% with a mean of 24.03±13.98%. Higher percentages of smudge cells (>30%) were statistically significantly associated with markers of better prognosis (negative ZAP-70, early-stage disease according to the Binet and Rai staging systems, as well as low and intermediate risk CLL prognostic index). The percentage of smudge cells showed significantly negative correlation with the ZAP-70 expression and higher area under the curve for prediction of ZAP-70 positivity with better survival for 36 months in patients with >30% smudge cells.

Conclusion: The percentage of smudge cells at presentation of newly diagnosed CLL patients could be used as a surrogate marker for ZAP-70 expression and an additional prognostic marker for disease progression.