A 30-year-old male patient complains of inertness, low-grade fever, bleeding gums, frequent quinsies, aching bones. Objectively: the patient has pale skin and mucous membranes, sternalgia, +2 cm liver, +5 cm painless spleen. Blood test results: RBC - 2,7x1012/l, Нb - 80 g/l, WBC - 3x109/l, eosinophils - 4%, basophils - 5%, blasts - 4%, stab neutrophils - 2%, segmented neutrophils - 17%, lymphocytes - 29%, myelocytes - 25%, promyelocytes - 12%, monocytes - 2%, platelets - 80x109/l, ESR - 57 mm/h. What test should be performed to verify the diagnosis?