Male patient age 6 years 9 months, native of the State of Mexico, without relevant antecedents. Parents age 32 years, with highschool level education, merchants; subject has a brother age 10 years and a sister age 4 years. His government vaccination plan is complete. Two months ago he presented onset of fever, epistaxis, and splenomegaly. At Hospital Materno Infantil de Toluca the blood biometry reported: hemoglobin 8.8 g/dL, hematocrit 24%, leukocytes 230,500/mm3, neutrophils 21%, bands 34%, lymphocytes 9%, monocytes 7%, blasts 14%, basophils 11%, eosinophils 4%. An analysis found: serum creatinine and liver function tests normal.