<prompt> A 9-year-old boy presents with fever, feeling unwell, and easy bruising on his legs. On examination he is pale, blood pressure 10060 mm Hg, pulse 100min, and temperature 37.8degC. His lungs are clear, abdomen is soft with a palpable spleen, and there are petechiae and bruises on his legs. His CBC reveals a hemoglobin of 8.5 gdL, WBC of 17,000mL, and platelets of 30,000mL. A blood film reveals neutropenia and leukemic lymphoblasts. Which of the following is the most appropriate initial diagnostic test to confirm the diagnosis?monospot testbone marrow aspirate and biopsyCT scan abdomenchest x-ray  <response>: In acute lymphoblastic leukemia ALL, a bone marrow analysis is the most important test in confirming the diagnosis. Once the diagnosis of ALL is established, CSF fluid leukemic cells in the CSF can be identified in up to a third of all patients at diagnosis and CXR are important tests in the workup of the patient. It is the most common malignancy in children under age 15 in the United States, accounting for 25 of all cancers in White children. It is less common in Black children. 