New developments in the understanding and diagnosis of myelodysplastic syndromes with ring sideroblasts☆

mutation, a diagnosis of MDS-RS may be defined with RS in yelodysplastic syndromes (MDS) represent a group of clonal ematopoietic stem cell disorders in which cytopenias of ariable severity are associated with dysplastic changes of ematopoietic precursors, and a higher risk of progression to cute myeloid leukemia (AML).1 Besides dysplasia, the presnce of ring sideroblasts (RS) has long been recognized as an mportant morphologic feature of MDS; it used to define a subet of patients within this group. Accordingly, the World Health rganization (WHO) criteria revised in 2008 defined refractory nemia with ring sideroblasts (RA-SR) as a specific MDS subroup, morphologically characterized by erythroid dysplasia nd the presence of at least 15% RS in bone marrow smears.2 However, seminal studies published within the last five ears have changed concepts and diagnostic definitions in he field of myeloid malignancies swiftly. Among these studes, made possible by the development of high-throughput equencing technologies, the description of mutations associted with MDS and AML in large patient cohorts,3–5 followed y the demonstration that some of these mutations are also resent (though with a lower allele burden) in individuals ithout evident hematologic alterations,6–8 led to the proposal f a new pathological category termed clonal hematopoiesis f indeterminate potential (CHIP).9 This could be conceptually iewed for myeloid neoplasms, as monoclonal gammopahy of undetermined significance is for multiple myeloma.