What is the prognosis for unclassifiable myelodysplastic syndromes (MDS-U)?

Updated: Jul 21, 2020
  • Author: Robert P Hasserjian, MD; Chief Editor: Christine G Roth, MD  more...
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Cases of unclassifiable myelodysplastic syndromes (MDS-U) should be followed carefully and should be reclassified as one of the defined myelodysplastic syndrome (MDS) subtypes if appropriate criteria are met after the initial evaluation (see Overview). Among cases lacking morphologic dysplasia but with a cytogenetic abnormality, the presence of monosomy 7 appears to be associated with evolution to other types of MDS (eg, refractory cytopenia with multilineage dysplasia [RCMD]) or acute leukemia. [17, 21]

Cases of MDS-U that are placed into this category because of 1% peripheral blood blasts show a significantly poorer prognosis and higher incidence of transformation to acute myeloid leukemia (AML) than cases of refractory cytopenia with unilineage dysplasia (RCUD) or refractory cytopenia with multilineage dysplasia (RCMD), akin to refractory anemia with excess blasts-1 (RAEB-1). [22] Although it is recommended that only one or two cytopenias be allowed for patients with RCUD (thus requiring that cases with unilineage dysplasia but pancytopenia be classified as MDS-U), it is unclear if these patients have an inferior prognosis to RCUD patients. Further study is needed on this group of patients with MDS-U to determine their clinical behavior.

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