Bone marrow changes refer to changes in the degree of bone marrow cell proliferation, bone marrow cell count, granulocyte-red ratio, and the ratio of hematopoietic cells in each system and stage. If the hematopoietic function is reduced, the bone marrow is “hypoproliferative” or “extremely hypoproliferative,” while in the case of leukemia, the bone marrow is “markedly active” or “extremely active. Extremely active” in leukemia. The following is an example of how to examine the bone marrow changes in leukemia. 1. The percentage of primitive cells exceeds 30%, which is usually considered as the main diagnostic criterion for acute leukemia. 2, Abnormally increased granulocytes, mainly in the mature stage. If the positive value of neutrophil alkaline phosphatase staining (NAP) staining is high, consider infection-induced leukemia-like reaction (a strong inflammatory reaction, not leukemia), while low positive value or negative is considered chronic granulocytic leukemia. 3. The erythrocyte system is markedly hyperplastic and is mostly hyperplastic anemia. 4. Granulocytes and erythrocytes are reduced, as are megakaryocytes, while an increased percentage of lymphocytes may be aplastic anemia.