Blood picture: White blood cell count was high at over 100×109/L. Most of the blood film consisted of neutrophilic rod-shaped nuclei and late juvenile granulocytes, and the rest of the blood film consisted of lobulated nuclei, intermediate juvenile granulocytes, early juvenile granulocytes, and a few primitive granulocytes. Eosinophils and basophils were also increased. Hemoglobin and erythrocytes are mildly decreased, platelets are normal or increased in the early stages, and erythrocytes and platelets are decreased in the late stages. In terms of blood picture, it must be differentiated from leukemia-like reaction. Bone marrow image: bone marrow is proliferative to extremely active, cell classification is similar to that of peripheral blood, in bone marrow films, granulocytes of various stages can be seen, with medium and late juvenile granulocytes predominantly, primary granulocytes and early juvenile granulocytes are increased compared with the normal ones, but generally not more than 5% to 10%, eosinophils and/or basophils are increased, erythrocyte lineage is relatively reduced, granulocytes: red is about 10-50:1, juvenile erythrocytes and megakaryocytes are increased in early stage and decreased in late stage. Alkaline phosphatase activity of mature neutrophils is significantly reduced in 90% of patients. Chromosomal examination: Ph’ chromosome is seen in more than 90% of patients with lentigo. Ph’ chromosome is considered to be a tumor marker of lentigo pluripotent stem cells, a few patients with lentigo are negative for Ph’ chromosome, according to the presence or absence of Ph’ chromosome, lentigo can be categorized as Ph’ positive and Ph’ positive. According to the presence or absence of Ph’ chromosome, lentigo can be categorized as Ph’ positive and Ph’ negative, and the prognosis of the former is better than that of the latter. Blood biochemistry: A significant increase in serum vitamin B12 concentration and vitamin B12 binding is one of the characteristics of the disease, and the magnitude of the increase is proportional to the degree of leukocytosis. The increase is due to excessive production of transcobalamin I, a vitamin B12 transporter, by a large number of normal and leukemic granulocytes.Serum uric acid concentrations can be increased, especially with chemotherapy.