[The clinical and laboratory features of acute promyelocytic leukemia: an analysis of 513 cases].

Objective: To investigate the clinical and laboratory features of acute promyelocytic leukemia (APL).

Methods: 513 APL patients in the last two decades were retrospectively analyzed in this research. We investigated the clinical features including age, sex, abnormality of peripheral hemogram before treatment, therapeutic effect and follow-up and laboratory data such as morphology, immunology, cytogenetics and molecular biology (MICM).

Results: The median age of the APL patients was 33 years old and the ratio of male and female was 1.21:1. Before treatment, the median level of WBC was 4.3 x 10(9)/L and the detection rate of abnormal promyelocyte on blood film was 85.8%; with immunophenotypic detection, the expression levels of CD117, CD34, HLA-DR, CD7, CD14 and CD19 in APL were found to be lower and the expression levels of CD2, CD33 and MPO higher than those in other subtypes of acute myelocytic leukemia (AML) (both P < 0.01). Specific abnormal chromosome t (15;17) was detected in 91.7% of the patients, of whom 75.9% had standard translocation of t (15;17), being the most common one and 15.8% of the patients had t (15;17) with additional abnormal chromosome. There was only 7.5% of the patients with normal karyotype. However, the presence of both simple translocation and complex translocation was seldom seen. With molecular biological detection, PML/RARalpha fusion gene positive rate was 99.6%. In a relatively long clinical follow-up, we found that the complete remission (CR) rate in APL patients was 84.7%, incidence of DIC was 13.4% and five-year survival rate was 30.7%. The median count of WBC in CR group was lower than that non-remission group (P < 0.01). There were no significant differences on expressions of CD34 and CD2 and changes of cytogenetics between the two groups (P > 0.05).

Conclusions: Comprehensive evaluation of MICM could be of important significance in the diagnosis and prognosis judgment for APL patients. The CR rate in these patients with high WBC count was considerable low.