Hematologic Malignancies USMLE Step 1 Practice Question

A 28-year-old man presents to the emergency department with a 2-week history of fever, drenching night sweats, and unintentional 8-pound weight loss. Physical examination reveals bilateral cervical and inguinal lymphadenopathy. CT chest/abdomen/pelvis shows extensive mediastinal, abdominal, and retroperitoneal lymphadenopathy. Laboratory studies reveal LDH of 2,840 U/L (normal <480) and uric acid of 9.2 mg/dL (normal 3.5-7.2). A biopsy of an abdominal lymph node demonstrates diffuse architectural effacement with medium-sized neoplastic cells displaying scant cytoplasm, round nuclei, and a very high mitotic rate. A starry-sky pattern created by tingible body macrophages is prominent. Immunophenotyping shows CD20+, CD10+, CD5−, BCL2−, and MYC translocation is detected by FISH. Which of the following is the most likely diagnosis?