Objective: To explore the expression of CD34 in patients with acute promyelocytic leukemia (APL) and investigate the clinical and laboratory features of CD34(+) APL patients.
Methods: 262 APL patients diagnosed by chromosome analysis and/or fusion gene examination in the last five years were retrospectively analyzed in this study. To survey the expression of CD34 in those patients, all the cases were divided into two groups (CD34(+) APL vs. CD34(-) APL). The clinical features including age, gender, abnormal values of the peripheral hemogram before treatment, the complete remission (CR) rate and the incidence of DIC and laboratory data such as the results of morphology, immunology, cytogenetics and molecular biology (MICM) between those two groups were compared.
Results: Of the 262 APL patients, 38 (14.5%) cases were positive for CD34 expression. There were no statistically significant differences between CD34(+) APL and CD34(-) APL groups in gender and age (P > 0.05). Before treatment, the median level of WBC in CD34(+) APL was 25.92 x 10(9)/L, which was significantly higher than that of CD34(-) APL (5.3 x 10(9)/L, P < 0.05). CD34(+) APL by morphology classification were mostly of the subtypes M3b and M3v (65.8%), while these subtypes in CD34(-) APL (40.3%) were significantly less (P < 0.01). There were no statistically significant differences between the two groups compared in respect of complete remission (CR) rate and the incidence of DIC (P > 0.05). The expression level of CD34 in APL had correlation to the expression level of CD2, CD7 and CD117; the latter three phenotypes in CD34(+) APL were significantly higher than those in CD34(-) APL (P < 0.01). No significant difference was found between those two groups by chromosome analysis, but there was more PML-RAR-alpha transcript short form in CD34(+) APL than that in CD34(-) APL (P < 0.05).
Conclusion: CD34(+) acute promyelocytic leukemia is a unique subtype of APL with different biological characteristics.