This disease is also called leukemia-like reaction, which means that the body is stimulated by certain factors, resulting in a significant increase in the number of peripheral white blood cells or the appearance of immature cells. It is very similar to leukemia but not leukemia. It is a temporary leukocyte hyperplasia reaction. Neutrophilia caused by various reasons, except for chronic myeloid leukemia, generally does not exceed 50×109/L, but occasionally it can exceed 50×109/L, or even 100×109/L. At the same time, the neutrophil nucleus in the blood shifts to the left significantly, and more metamyelocytes, myelocytes, and even a small number of promyelocytes and myeloblasts appear. This phenomenon is somewhat similar to chronic myeloid leukemia, so it is called a leukocyte-like reaction. There are many types, including granulocytic type, erythroleukemia type, plasma cell type and mixed cell type, among which neutrophil type is the most common.