Atypical immunophenotype of chronic lymphocytic leukemia

Abstract

Assessment of the immunophenotype plays a crucial role in the diagnostic process of chronic lymphocytic leukemia (CLL). The expression of CD5, CD19 and CD23 antigens with a concomitant reduction or lack of surface immunoglobulin expression as well as CD22 and CD79b antigens is the basic part of CLL diagnosis. A significant diagnostic challenge is atypical CLL with cells devoid of CD5 or CD23 antigens. The assessment of additional antigens in flow cytometry, especially the CD200 glycoprotein, may facilitate the process of differential diagnosis of atypical CLL from other B-cell lymphoproliferative neoplasms. The results of current studies analyzing the influence of atypical CLL on prognosis are inconclusive. The analysis of a large group of patients with atypical CLL is difficult because of the rare occurrence of CD5(-) or CD23(-) CLL and the misdiagnosis of this disease as other B-cell lymphoproliferative neoplasms. The following paper aims to show how important it is to include atypical CLL in the diagnostic process of this disease and to re-standardize the commonly used immunophenotypic scales for its diagnosis.