A 47-year-old man with newly diagnosed mantle cell lymphoma (MCL) presents for evaluation. He has no other past medical history. He works as a mechanic. On exam he has multiple abnormal lymph nodes palpable in the neck, axillae, and groin. He reports that he feels poorly. Laboratory evaluation reveals an elevated white blood cell (WBC) count and elevated lactate dehydrogenase (LDH) level. Computed tomography (CT) scan demonstrates diffuse lymphadenopathy. He is found to have stage III disease involving multiple lymph nodes in the cervical, mediastinal, and inguinal areas. Bone marrow biopsy is negative for involvement. His MCL International Prognostic Index (MIPI) score is high risk. Lymph node biopsy reveals sheets of medium-sized lymphocytes that are clonal, CD20+, CD5+, and CD23–, and cyclin D1 stains strongly.