A 10-year-old girl was brought to an outpatient clinic because she complained of a sore throat and a lump in her neck. On examination, she was observed to have a tonsillar abscess, swollen glands, and widespread bruising in the extremities. She also had a low-grade fever. She was treated with antibiotics and released, but she failed to progress over the next 2 days. Hematology laboratory tests revealed a WBC of 8.0 x 10^9/L, a hematocrit of 28%, and a platelet count of 10 x 10^12/L. Peripheral blood differential count revealed 3 band neutrophils, 25 segmented neutrophils, 8 lymphocytes, 1 monocyte, and 63 blasts. The patient’s parents were contacted, and the girl was immediately admitted to the hospital. A bone marrow examination was performed and revealed an infiltration of blast cells in the marrow. Immunophenotyping was performed on the bone marrow cells. The results show the cells have CD11b, CD13, CD33, and CD15 markers.