Diagnosis and classification of myelodysplastic syndrome: International Working Group on Morphology of myelodysplastic syndrome (IWGM-MDS) consensus proposals for the definition and enumeration of myeloblasts and ring sideroblasts

Abstract

The classification of myelodysplastic syndromes is based on the morphological criteria proposed by the French-American-British (FAB) and World Health Organization (WHO) groups. Accurate enumeration of blast cells, although essential for diagnosis of myelodysplastic syndrome and for assignment to prognostic groups, is often difficult, due to imprecise criteria for the morphological definition of blasts and promyelocytes. An International Working Group on Morphology of Myelodysplastic Syndrome (IWGM-MDS) of hematopathologists and hematologists expert in the field of myelodysplastic syndrome reviewed the morphological features of bone marrows from all subtypes of myelodysplastic syndrome and agreed on a set of recommendations, including recommendations for the definition and enumeration of blast cells and ring sideroblasts. It is recommended that (1) agranular or granular blast cells be defined (replacing the previous type I, II and III blasts), (2) dysplastic promyelocytes be distinguished from cytologically normal promyelocytes and from granular blast cells, (3) sufficient cells be counted to give a precise blast percentage, particularly at thresholds that are important for diagnosis or prognosis and (4) ring sideroblasts be defined as erythroblasts in which there are a minimum of 5 siderotic granules covering at least a third of the nuclear circumference. Clear definitions and a differential count of a sufficient number of cells is likely to improve precision in the diagnosis and classification of myelodysplastic syndrome. Recommendations should be applied in the context of the WHO classification.

Spliceosome mutations involving SRSF2, SF3B1, and U2AF35 in chronic myelomonocytic leukemia: Prevalence, clinical correlates, and prognostic relevance

“…The presence of 15% RS constitutes the operational diagnosis of MDS-RS [33]. Sixty-four (28%) of the study patients had 1% RS, with 41% of these having 15% RS.…”

“…RS are erythroid precursors with iron-laden mitochondria forming a perinuclear ring and are common in patients with myeloid neoplasms, including MDS, MPN, and MDS/MPN overlap syndromes [1,17,33]. The presence of 15% RS constitutes the operational diagnosis of MDS-RS [33].…”

46-Year-Old Man With Fevers, Chills, and Pancytopenia

“…Myelodysplastic syndrome encompasses a diverse group of malignant stem cell disorders that are characterized by dysplastic and ineffective blood cell production. 7 Myelodysplastic syndrome is diagnosed based on the peripheral blood smear and bone marrow biopsy findings. Because work-up results for both infectious and hematologic causes were negative, the patient's recent use of trimethoprim-sulfamethoxazole was considered the most likely cause of his pancytopenia.…”

Leukocyte morphology on an anti-CD antibody microarray for acute leukemia diagnosis: morphology rejuvenated

“…As morphology and flow cytometry use different methods to define the blast population, blasts detected by these two methods are not necessarily the same. 5,6 This fact can lead to differences in the size of blast population determined by morphology and flow cytometry, as well as pose problems in attributing the leukemic cells to different lineages and determining the leukemia subtype.To solve this problem and to integrate the morphology and immunophenotyping in the acute leukemia diagnosis we would need a method permitting the morphology study and the surface clusterof-differentiation antigen determination on the same cells. Several approaches have been tried to this end.…”