A 42-year-old man presents with a lump in his neck that he noticed while shaving. He denies any symptoms such as fatigue, weight loss, night sweats, or itchy skin. On exam, a large 3-cm lymph node in his left neck is easily palpable as are several lymph nodes in his right axilla. CT scan confirms the presence of the cervical and axillary nodes, which measure 3.5 cm. Excisional biopsy of the neck node reveals mostly small lymphocytes in a diffuse nodular infiltrative pattern with scattered histiocytes and large mononuclear multilobated popcorn-looking cells. These cells are positive for CD20, CD79a, DC75, BCL6, and CD45. They are negative for CD30 and CD15.