Bone Marrow Findings in Myelodysplastic Syndromes (MDS)

Diagnostic Criteria

The World Health Organization (WHO) classification defines MDS subtypes based on bone marrow blast percentage, dysplastic changes, and cytogenetic abnormalities 1, 2
The International Prognostic Scoring System (IPSS) categorizes MDS into low, intermediate-1, intermediate-2, and high risk based on bone marrow blasts, karyotype, and cytopenias 2, 4

Refractory Cytopenia with Unilineage Dysplasia (RCUD) is characterized by dysplasia in one myeloid lineage, blast percentage <5%, and ring sideroblasts <15% 1, 2
Refractory Anemia with Ring Sideroblasts (RARS) is defined by ring sideroblasts ≥15%, erythroid dysplasia only, and blast percentage <5% 1, 2
Refractory Cytopenia with Multilineage Dysplasia (RCMD) shows dysplasia in two or more myeloid lineages, blast percentage <5%, and ring sideroblasts may be present 1, 2

Refractory Anemia with Excess Blasts-1 (RAEB-1) is characterized by bone marrow blasts 5-9%, unilineage or multilineage dysplasia, and Auer rods absent 1, 2
Refractory Anemia with Excess Blasts-2 (RAEB-2) is defined by bone marrow blasts 10-19%, unilineage or multilineage dysplasia, and Auer rods may be present 1, 2

Bone marrow blast count is the most critical prognostic parameter, with higher counts associated with increased risk of AML progression and shorter survival 1, 2, 6
Cytogenetic abnormalities, such as del(5q), -7/del(7q), and complex karyotype, have significant prognostic impact and can establish MDS diagnosis even with minimal dysplasia 1, 3, 8

Bone marrow aspirate and biopsy are essential for evaluating dysplasia, blast enumeration, and cellularity, and for assessing topographic abnormalities and fibrosis 5, 6, 7
Cytogenetic analysis is crucial for identifying clonal abnormalities and determining prognosis 3, 8