A 35-year-old man complains of persisting enlargement of his peripheral lymph nodes that cause him no discomfort. The case history states that the first lymph nodes to enlarge were cervical, supraclavicular, and axillary; new groups of lymph nodes emerged. Objectively the lymph nodes are soft and elastic on palpation, enlarged, painless, not fixed to the surrounding tissue. What examination method would be the most informative for early diagnostics of this disease?