NCCN Guidelines for Patients® | Myelodysplastic Syndromes

11 NCCN Guidelines for Patients ® : Myelodysplastic Syndromes, 2018 1 Myelodysplastic syndromes Types of MDS † † The presence of red blood cells that have too much iron (ring sideroblasts). MDS subtypes in the WHO classification system MDS-UD (MDS with unilineage dysplasia) In this subtype, there is a low number of one type of blood cells in the bloodstream. The same type of blood cell looks abnormal in the bone marrow. For the affected cell type, at least 10 percent of the cells look abnormal (show dysplasia). No blast cells are found in the bloodstream. Less than 5 percent of cells in the bone marrow are blast cells. MDS-RS (MDS with ring sideroblasts) In this subtype, there is a low number of red blood cells in the bloodstream. Red blood cells are also abnormal in the bone marrow. At least 15 percent of young red blood cells in the bone marrow are ring sideroblasts. Less than 5 percent of cells in the bone marrow are blast cells. No blast cells are found in the bloodstream. There is a normal number of white blood cells and platelets in the bloodstream and these cells look normal in the bone marrow. MDS-MD (MDS with multilineage dysplasia) In this subtype, there is a low number of one or more types of blood cells in the bloodstream. Two or more types of blood cells look abnormal in the bone marrow. Of the affected cell types, at least 10 percent of the cells look abnormal. Some young blood cells in the bone marrow may be ring sideroblasts. Overall, less than 5 percent of cells in the bone marrow are blast cells. No blast cells are found in the bloodstream. MDS-EB1 (MDS with excess blasts-1) In this subtype, one or more types of blood cells are low in the bloodstream and also look abnormal in the bone marrow. The number of blast cells is higher than normal. Less than 5 percent of cells in the bloodstream are blast cells. In the bone marrow, 5 percent to 9 percent of cells are blast cells. MDS-EB2 (MDS with excess blasts-2) In this subtype, one or more types of blood cells are low in the bloodstream and also look abnormal in the bone marrow. The number of blast cells is higher than normal. Five to 19 percent of cells in the bloodstream are blast cells and 10 to 19 percent of cells in the bone marrow are blast cells. MDS-U (MDS, unclassified) In this subtype, the features of the blood and bone marrow don’t fit any of the other subtypes. One or more types of blood cells are low in the bloodstream, but less than 10 percent of that cell type looks abnormal in the bone marrow. Very few or no blasts are found in the bloodstream on at least 2 occasions and less than 5 percent of cells in the bone marrow are blast cells. Cells in the bone marrow have at least one abnormal chromosome change that is linked with MDS. MDS associated with isolated del(5q) In this subtype, cells in the bone marrow have only one abnormal chromosome change. This change is called del(5q), which means that part of chromosome 5 is missing (deleted). In some circumstances, one additional abnormal chromosome can be present. There is a low number of red blood cells in the bloodstream and the number of platelets is normal or high. Less than 5 percent of cells in the bone marrow are blast cells.

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