Robert P. Hasserjian¹

¹Department of Pathology, Massachusetts General Hospital, Boston, MA, USA

 

Myelodysplastic syndromes (MDSs) are neoplastic proliferations originating from mutated hematopoietic stem cells that mature abnormally, resulting in peripheral blood cytopenias.  Most MDS cases are preceded by a pre-malignant state of clonal hematopoiesis (CH), and they are separated by CH from the identification of morphologic dysplasia seen in bone marrow and peripheral blood cells. MDS is distinguished from acute myeloid leukemia (AML) by the presence of relatively preserved hematopoietic maturation. Establishing an initial diagnosis of MDS requires the integration of clinical features (blood counts and patient history), morphology, immunophenotyping, and genetic testing. MDS is biologically heterogeneous and is subdivided into several distinct entities by formal classification schemes, most recently updated in 2022: the International Consensus Classification (ICC) and 5^th edition World Health Organization Classification (WHO5). Despite some differences in nomenclature and definitions of individual MDS entities, both ICC and WHO5 place increased emphasis on genetic features (mutations and specific cytogenetic aberrations) in comparison to prior classification systems.  The specific MDS subtype, along with prognostic risk scoring, critically informs clinical decision making, emphasizing the importance of accurate diagnosis and classification.  

 

References:

 

1.     Hasserjian RP, Germing U, Malcovati L. Diagnosis and classification of myelodysplastic syndromes. Blood. 2023 Dec 28;142(26):2247-2257.

2.     Komrokji RS, Lanino L, Ball S, et al. International Consortium on Myelodysplastic Syndromes. Data-driven, harmonised classification system for myelodysplastic syndromes: a consensus paper from the International Consortium for Myelodysplastic Syndromes. Lancet Haematol. 2024 Nov;11(11):e862-e872.