Clinical features and treatment outcomes of pediatric acute promyelocytic leukemia in a Mexican pediatric hospital

Introduction. Acute promyelocytic leukemia (APL) is a distinct type of acute myeloid leukemia (AML) characterized by chromosomal translocations involving the retinoid acid receptor (RARA) gene on chromosome 17. APL is a relatively rare blood disease that is highly curable with current treatment strategies; however, patient outcomes are heterogeneous in countries with limited resources. Promyelocytic leukemia accounts for 20-25% of all AML cases in Latin American countries. Material and methods. We conducted a study from July 2007 to July 2012 and applied the IC-APL2006 protocol. This case study reports the results from eleven patients with AML M3 (five males and six females). In all cases, the diagnoses were made by aspirating bone marrow and evaluating the t(15:17) or t(11:17) transcript. In eight cases, the molecular biology-based diagnostics for the PLM-RARa transcript were positive, and they were negative in two cases. One patient was positive for the PLZF-RARa transcript. Results. The mean WBC at the time of diagnosis was 10.1 x 10(9)/L, and the mean platelet count was 17.1 x 10(9)/L. The mean percentage of abnormal promyelocytes in the bone marrow aspirates was 68%. Of the eleven patients, four presented with disseminated intravascular coagulation. All of the patients began treatment with transretinoic acid (ATRA) (45 mg/m(2)/day), which led to 4 cases of ATRA syndrome. There were 2 relapses, and the patient died in one case. The remaining ten patients were alive after the median follow-up period of 33.6 months (range from 11 to 60 months). Conclusion. The authors report on a series of cases involving pediatric patients with AML M3 seen at a single institution; the patients were stratified and treated with a standard protocol to obtain satisfactory results. Although the number of patients is limited, the health outcomes are relevant. To our knowledge, this is the first series of pediatric APL patients in Mexico who were treated with the IC-APL2006 protocol.