Snapshot A 11-year-old girl with Down syndrome presents with a few weeks of low-grade fever. She is otherwise feeling well, with no signs of infection. Blood-work shows elevated WBCs, low neutrophil count, and anemia. Blood cultures are drawn and come back positive for Pseudomonas. Introduction Acute leukemia of lymphoid precursor cells that occurs in children Crowding of bone marrow leads to bone marrow failure Subtypes B-cell ALL – 85% of all ALL CD10+ and CD19/20+ TdT+ (marker of precursor T- or B-cell) T-cell ALL CD2+, CD8+, and CD3+ TdT+ (marker of precursor T- or B-cell) commonly presents as mediastinal mass infiltration of thymus Epidemiology < 15 years most common type of cancer and leukemia in children Associated conditions Down syndrome in children > 5 years leukemia in Down syndrome children < 5 years = AML ALL Blood Smear Presentation Symptoms most common symptom is fever acute onset recurrent infections bleeding fatigue Physical exam mediastinal mass from infiltration of thymus hepatosplenomegaly lymphadenopathy Evaluation Peripheral blood smear ↑ lymphoblasts (high nuclei to cytoplasm ratio) CBC reflects bone marrow failure anemia thrombocytopenia ↓ mature WBCs Bone marrow aspiration with cytogenetics ↑ lymphoblasts TdT+, a marker of pre-T and pre-B cells T-cell ALL CD2+ CD3+ B-cell AML CD10+ CD19+ negative MPO (myeloperoxidase) t(12:21) Differential Diagnosis AML B-cell lymphoma Non-hodgkin lymphoma Treatment Chemotherapy Prophylaxis to CNS (standard chemotherapy does not penetrate blood-brain barrier) intrathecal chemotherapy Prognosis, Prevention, and Complications Prognosis very responsive to therapy Complications likes to spread to CNS and testes