Myeloproliferative disease (MPD) belongs to a group of hematopoietic stem cell tumor proliferative diseases, which is the persistent abnormal hyperproliferation of one or more bone marrow cells. The proliferating cells can be erythrocytes, granulocytes, megakaryocytes or fibroblasts. Erythrocytosis is called polycythemia vera (PV). Chronic myeloid leukemia is mainly caused by granulocyte proliferation. Primary thrombocytosis (ET) is mainly caused by megakaryocyte proliferation. Primary myelofibrosis (PMF) is mainly caused by the proliferation of fibroblasts. If multiple strains proliferate, it is difficult to judge which strain is dominant, which is called unclassified myeloproliferative disease (MPD-U). The etiology of this group of diseases is unknown, and it is more common in middle-aged and elderly people aged 50-60. The onset of the disease is hidden, the course of the disease progresses slowly, and it is often accompanied by hepatosplenomegaly, which is easy to be complicated with bleeding and thrombosis. The end stage is often caused by bone marrow fibrosis, systemic failure or transformation into acute leukemia. In 200 1 year, the World Health Organization (WHO) classified chronic neutrophilic leukemia (CNL), chronic eosinophilic leukemia/hypereosinophilic syndrome (CEL /HES) and mast cell disease (MCD) as MPD. In 2008, the newly revised WHO classification of chronic myeloid cell line tumors renamed MPD as myeloproliferative tumor (MPN) to emphasize the tumor nature of this group of diseases, so myeloproliferative diseases (MPD) were renamed as myeloproliferative tumors (MPN).