A 60-year-old male presents with fatigue and tiredness for 6 months, along with low-grade fever and poor appetite for 1 month. Physical examination reveals a mild anemic appearance, multiple bean-sized, hard, non-tender lymph nodes in the neck, non-palpable liver, and spleen 2 cm below the costal margin. Laboratory tests show Hb 81g/L, WBC 4×10<sup>9</sup>/L, PLT 125×10<sup>9</sup>/L, with differential counts of neutrophils 22%, lymphocytes 75%, monocytes 3%, and reticulocytes 12%. Coombs test is positive. The most likely diagnosis is: