Bone Marrow Aspiration Findings in Myeloid Disorders

Diagnostic Criteria

The National Comprehensive Cancer Network recommends that a blast count ≥20% in bone marrow or peripheral blood defines Acute Myeloid Leukemia (AML) by WHO criteria 4, 6
The American Society of Clinical Oncology states that dysplasia in ≥10% of cells in at least one myeloid lineage is required for diagnosis of Myelodysplastic Syndromes (MDS) 7, 8, 6
The European Society for Medical Oncology notes that a BCR::ABL1 fusion is the defining molecular feature of Chronic Myeloid Leukemia (CML), detected by cytogenetics showing t(9;22) Philadelphia chromosome in 85-90% of cases, or by FISH/RT-PCR in cryptic cases 1
The International Society for Laboratory Hematology recommends that cytogenetic analysis of 20-25 metaphases is mandatory in all suspected myeloid neoplasms to detect clonal abnormalities and establish diagnosis 7, 1, 6

The National Comprehensive Cancer Network states that CML bone marrow shows marked hypercellularity with granulocytic hyperplasia and a left shift in myeloid maturation, with blasts typically <10% in chronic phase 1
The American Society of Hematology notes that basophilia and eosinophilia are commonly present in CML, with basophils often increased 1

The National Comprehensive Cancer Network recommends that peripheral blood monocytosis ≥1×10⁹/L sustained for >3 months with monocytes comprising ≥10% of white blood cells is mandatory for diagnosis of CMML 3
The International Society for Laboratory Hematology states that multilineage dysplasia is prominent in CMML, with dysplastic granulocytes, erythroid precursors, and megakaryocytes characteristic 2

The American Society of Clinical Oncology notes that AML bone marrow is characterized by ≥20% myeloblasts with replacement of normal hematopoietic elements 4, 5
The European Society for Medical Oncology recommends that immunophenotyping shows blasts expressing CD34, CD117, HLA-DR, and myeloid markers (CD13, CD33, MPO) in AML 4

The National Comprehensive Cancer Network states that MDS bone marrow shows dysplastic changes in ≥10% of cells in one or more lineages with blasts <20%, often with hypercellular marrow paradoxically producing peripheral cytopenias 7, 8, 6
The International Society for Laboratory Hematology notes that ring sideroblasts ≥15% define the RARS subtype of MDS, with erythroid precursors having iron-laden mitochondria encircling the nucleus on iron stain 2, 9

The American Society of Clinical Oncology recommends that blast enumeration requires a 500-cell differential on bone marrow aspirate to ensure accuracy 7, 5, 10
The National Comprehensive Cancer Network states that CD34 immunohistochemistry is invaluable when marrow is hypocellular, fibrotic, or yields a dry tap, allowing blast quantification when morphology is inadequate 5, 10