Hematologic Malignancies USMLE Step 1 Practice Question

A 10-year-old boy presents to the emergency department with a 3-week history of progressive jaw swelling and pain. His mother reports he has had fever (38.2°C) and appears fatigued. On examination, there is a firm, non-tender mass of the left mandible with buccal mucosa involvement. The liver and spleen are not enlarged. Laboratory studies reveal: WBC 8,500/μL, hemoglobin 11.2 g/dL, platelets 180,000/μL, LDH 720 U/L, and uric acid 8.4 mg/dL. A biopsy of the mandibular mass shows medium-sized lymphoid cells with abundant cytoplasm, high mitotic rate, and starry-sky appearance. Cytogenetic analysis demonstrates t(8;14)(q24;q32). Which of the following is the most likely diagnosis?