7/14/2023 0 Comments Who fab rcud rcmdUnilineage dysplasia: ≥10% of cells in one myeloid lineage Refractory cytopenia with unilineage dysplasia (RCUD) In summary, the WHO classification appears to define morphological subgroups that are more homogeneous with respect to prognosis than the FAB subtypes. Furthermore, patients with 5q – anomaly had a much better prognosis than other WHO subtypes, but this was only true for patients with a medullary blast count below 5%. There is a significant difference in prognosis between RAEB I and RAEB II, as well as a difference between refractory anemia and multilineage dysplasia. MDS patients with 5q – as the sole chromosomal anomaly were also considered a separate group. In addition, a group of patients with less than 5% medullary blasts but evidence of multilineage dysplasia was defined. In the recent WHO classification, CMML and RAEB-T were removed from the MDS classification and RAEB was split into two groups with medullary blast counts below and above 10%. The classification system as proposed by FAB included the following subtypes – refractory anemia (RA), refractory anemia with ring sideroblasts (RARS), refractory anemia with excess blasts (RAEB), refractory anemia with excess blasts in transformation (RAEBT), and chronic myelomonocytic leukemia (CMML). A working group of the World Health Organization (WHO) recently proposed a new classification of MDS ( Table 1), based on a significant modification of the original FAB proposals. 6 Myeloblasts in the peripheral blood and bone marrow are <20%. 4, 5 Values above these thresholds are not exclusionary for a diagnosis of MDS if definitive morphologic or cytogenetic findings are present. 1 – 3 The thresholds for cytopenia(s) as recommended in the International Prognostic Scoring System (IPSS) for risk stratification in the MDS are hemoglobin <10 g/dl, absolute neutrophil count (ANC) <1.8 × 10 9/L and platelets <100 × 10 9/L. The myelodysplastic syndromes (MDS) are a group of clonal hematopoietic stem cell diseases characterized by cytopenia(s), dysplasia in one or more of the major myeloid cell lines, ineffective hematopoiesis, and increased risk of development of acute myeloid leukemia (AML). The clinicopathologic features, morphology, differential diagnosis, immunophenotyping, cytogenetics, prognosis and predictive factors are presented in the light of recent World Health Organization Classification of Tumors – International Agency for Research on Cancer. The myelodysplastic syndromes are now classified into the following categories – refractory cytopenia with unilineage dysplasia, refractory anemia with ring sideroblasts, refractory cytopenia with multilineage dysplasia, refractory anemia with excess blasts, myelodysplastic syndrome associated with isolated del (5q), myelodysplastic syndrome – unclassifiable, and childhood myelodysplastic syndrome. The classification and the diagnostic criteria have been redefined by the recent World Health Organization Classification of Tumors – International Agency for Research on Cancer for Hematopoietic and Lymphoid Tissues. The myelodysplastic Syndromes (MDS) are a group of clonal hematopoietic stem cell diseases characterized by cytopenia(s), dysplasia in one or more of the major myeloid cell lines, ineffective hematopoiesis, and increased risk of development of acute myeloid leukemia.
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