What are myeloproliferative neoplasms?

Myeloproliferative neoplasm is a relatively rare disease with a relatively low incidence rate. Many people do not know much about it. What exactly is myeloproliferative neoplasm? In fact, myeloproliferative neoplasm is a disease caused by the continuous excessive growth of bone marrow cells. The function of the bone marrow is hematopoiesis. Once myeloproliferative neoplasm occurs, various blood diseases will definitely occur due to the disorder of hematopoietic function, which is very harmful.

Clinically, it is divided into four types according to the main cell series of proliferation: ① The one in which the red blood cell series is mainly hyperplastic is called true polycythemia. ② Chronic myeloid leukemia (CML) is characterized by granulocyte proliferation. ③The disease characterized by megakaryocyte proliferation is called essential thrombocythemia. ④ The disease characterized by the proliferation of fibroblasts is called primary myelofibrosis. The causes of this group of diseases are unknown and are more common in middle-aged and elderly people. CML See leukemia. The following are three other types.

Polycythemia vera

It is an unexplained condition in which the total amount of red blood cells in the body is significantly higher than normal, commonly known as plethora of blood. 30% of patients develop myelofibrosis, which eventually leads to bone marrow failure, and about 10% of patients develop acute leukemia. The disease has a slow onset and due to the increase in circulating red blood cells and blood viscosity, it causes headaches and dizziness, and some may even develop bleeding and thrombosis. There may be increased blood pressure and splenomegaly, peripheral blood hemoglobin as high as 18-23 g/dL, hematocrit 55%-80%, isotope measurement of increased red blood cell volume (≥36 ml for men and ≥32 ml for women per kilogram of body weight), blood oxygen saturation >92%. The diagnosis can be made after excluding other secondary erythrocytosis. Phlebotomy is a convenient and easy symptomatic treatment that can reduce blood volume to normal in a short period of time. Radioactive isotopes of phosphorus or hydroxyurea and Myleran all have obvious therapeutic effects.

Essential thrombocythemia

Less common, it is characterized by a marked increase in platelets, accompanied by bleeding or thrombosis. The incidence rate between men and women is 2:1. 8% of patients develop myelofibrosis and 10% of patients develop acute leukemia. The disease has a slow onset, the spleen may enlarge, the peripheral blood platelet count continues to increase to more than 600×109/L, and the platelet adhesion, aggregation and factor 3 function may be reduced. The diagnosis can be made after excluding other myeloproliferative diseases and reactive thrombocytosis. If the platelet count is >1000×109/L and there is bleeding, apheresis machine can be used to quickly remove excess platelets in the blood. Hydroxyurea, myleran or 23-phosphorus have satisfactory therapeutic effects.

Primary myelofibrosis

It is a diffuse fibrous proliferation of the bone marrow of unknown cause, accompanied by extramedullary hematopoiesis (or myeloid metaplasia), mainly in the spleen, but also in the liver and lymph nodes. It is generally believed that myeloid metaplasia is not a compensatory effect of myelofibrosis, but a manifestation of myeloproliferation. The disease is characterized by an insidious onset and a course of more than 10 years. There is a progressive and obvious enlargement of the spleen, and sometimes the entire abdomen is occupied by the spleen. Due to extramedullary hematopoiesis, immature red blood cells, immature granulocytes and teardrop-like red blood cells appear in the peripheral blood. The bone marrow is difficult to puncture due to fibrosis, and the bone marrow is often unable to be taken out, which is called "dry extraction". A bone marrow biopsy can confirm the diagnosis. There is no radical cure yet, and treatment is mainly symptomatic and supportive. Splenomegaly with compression symptoms, hyperfunction or rupture can be removed. The use of 1,25(OH)2D3 to treat fibrosis has a certain effect, but attention should be paid to elevated blood calcium. The cause of death from this disease is bone marrow failure or unrelated diseases such as cardiovascular disease. About 10% to 20% of patients eventually develop acute leukemia.