Hematologic Malignancies USMLE Step 1 Practice Question

A 28-year-old man presents to the emergency department with severe abdominal pain, high fever (39.2°C), and tachycardia (HR 118/min). He reports a 2-week history of progressive fatigue and night sweats but denies recent infections or chemotherapy. Physical examination reveals splenomegaly and abdominal tenderness. Laboratory studies show: WBC 45,000/μL with 85% blasts Hemoglobin 10.2 g/dL Platelets 95,000/μL LDH 3,200 U/L Uric acid 8.9 mg/dL Creatinine 2.1 mg/dL (baseline 0.9 mg/dL) Phosphate 5.2 mg/dL (normal 2.5-4.5) CT abdomen shows a rapidly enlarging abdominal mass. Tumor lysis labs are concerning. Which of the following is the most likely diagnosis?