This study investigated the clinical characteristics and prognostic relevance of CD34 expression in 47 patients with acute promyelocytic leukemia (APL), showing t(15;17) or PML/RARalpha. Ten (21.3%) of the APL patients were CD34(+). CD34 expression was associated with hypogranular morphology (P = 0.002) and hyperleukocytosis (P = 0.015). However, there were no statistically significant differences in age, sex, hemoglobin level, platelet count, or percentage of blasts between the CD34(+) and CD34(-) APL groups. Multiplex RT-PCR analysis showed that the L-form (BCR1) and S-form (BCR3) were correlated with CD34(-) APL and CD34(+) APL, respectively. Despite the lack of a difference in the complete remission rate, overall survival (OS) and disease-free survival (DFS) were significantly lower in the CD34(+) group than in the CD34(-) group (P = 0.012 and P = 0.0051, respectively). By multivariate analysis, the CD34(+) group showed a significant independent variable in DFS compared with the CD34(-) group, but this was not demonstrated for OS. In conclusion, CD34 expression in APL is a unique clinical feature associated with leukocytosis and atypical morphology with hypogranular pattern and is associated with a poor clinical outcome.
Copyright 2003 Wiley-Liss, Inc.