Myelodysplastic Syndromes (MDS) include multiple hematologic neoplasms characterized by dysplasia and ineffective hematopoiesis. Before the WHO reclassification in 2016, the group was known as Refractory Anemia. Some, although not all MDS, eventually terminate as Acute Myeloid Leukemia (AML). Prognosis and treatment vary significantly among this group and depend on many factors, including the number and degree of cytopenias.
The causes of MDS include mutagenic chemicals, chemotherapy, radiation, etc., although some are idiopathic. This group has many different chromosomal and genetic abnormalities. The specific type of MDS is diagnosed based on the number and type of dysplastic cell lines and the absence or presence of abnormal numbers of blasts.
The 2016 WHO groups of MDS include:
- MDS with single lineage dysplasia
- MDS with ringed sideroblasts (MDS-RS)
- MDS with multilineage dysplasia (MDS-MLD)
- MDS with excess blasts (MDS-EB): 2 subgroups include MDS-EB1 and MDS-EB2
- MDS with isolated del(5q)
- MDS unclassifiable (MDS-U)
- Overlap syndromes include myelodysplastic/myeloproliferative neoplasm with ringed sideroblasts and thrombocytosis (MDS/MPN-RS-T), and MDS/MPN unclassifiable
