A 74 year-old man presents to your office because he is concerned about a small lump in the right axilla. He reports ‘I am fine otherwise’. He denies any fatigue, fever, night sweats or weight loss. Physical examination is significant only for a palpable small lymph node in the right axilla. You ordered a complete blood count which is significant for a white blood cell count of 94,300 /mm³. Peripheral smear shows lymphocytosis with many smudge cells. Of the following, what is the next best step in the management of this patient?
