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PubMed This is a summary of 18 peer-reviewed journal articles Updated
Hematology

Deciphering Your Bone Marrow and Pathology Report

At a Glance

A complete myelodysplastic syndrome (MDS) pathology report must include morphology, cytogenetics, and Next-Generation Sequencing (NGS). Together, these tests measure your blast count, map your chromosomes, and identify specific genetic mutations to accurately guide your treatment plan.

Your bone marrow pathology report is the most important document in your medical file. It is the “blueprint” of your disease, providing the evidence that confirms your diagnosis and determines your risk level. However, these reports are often written in a technical shorthand that can be difficult for anyone without a medical degree to decipher.

To ensure your care team has the information they need to build your treatment plan, you can “audit” your own report to make sure it contains the three pillars of a modern MDS diagnosis [1][2].

What to Expect: The Bone Marrow Biopsy Procedure

A bone marrow biopsy is the most critical test, but anticipation of it can cause massive anxiety. During the procedure, your doctor will numb an area on the back of your hip bone with local anesthetic. They then use a specialized needle to draw out a small amount of liquid marrow (the aspiration) and a tiny core of bone (the biopsy). While you may feel pressure and a brief, sharp drawing sensation, the procedure typically takes only 10 to 15 minutes. Understanding this process can help demystify the physical test that generates your pathology report [3].

The Three Pillars of a Complete Report

A modern, 2022-standard pathology report should not just say “MDS.” It must provide specific data from three different types of tests:

  1. Morphology: This is what the pathologist saw through the microscope. It should include the blast percentage and a description of dysplasia (abnormal cell shapes) [4][5].
  2. Cytogenetics (Karyotype): This test maps your chromosomes. It looks for structural changes, such as a missing piece of chromosome 5 (del(5q)) or a “complex karyotype” (3 or more abnormalities) [6][7].
  3. Molecular Genetics (NGS): Short for Next-Generation Sequencing, this scans your DNA for specific gene mutations that act as the “drivers” of your MDS [8].

Key Technical Terms to Look For

When you review your report, you will likely see these terms. Here is what they actually mean:

  • Blasts: These are immature cells. In MDS, they should usually be under 20%. Crossing the 20% mark (or 10% in some newer classification systems) can change the diagnosis to Acute Myeloid Leukemia (AML) [9][10].
  • Cellularity: This describes how many cells are in your marrow. Most MDS patients have hypercellular marrow, meaning it is “overcrowded” with cells that can’t mature properly [11].
  • TP53 “Multi-hit” vs. “Single-hit”: This is a critical modern distinction. A single-hit means only one copy of the TP53 gene is mutated. A multi-hit (or biallelic) means both copies are broken, which is a high-risk finding that signals a more aggressive disease [12][13].
  • SF3B1 Mutation: This is often a “favorable” finding. It is frequently associated with ring sideroblasts and a slower-moving disease [14][15].
  • ASXL1 Mutation: Finding this mutation often indicates a higher risk of the disease progressing over time [16].

Your Completeness Checklist

If your report is missing any of these items, your diagnosis or risk score may be incomplete. Check your report for:

  • [ ] Blast Count: Expressed as a percentage (e.g., “3% blasts”).
  • [ ] Cytogenetics/Karyotype: A list of chromosome numbers (e.g., “46,XY” or “46,XY,del(5q)”).
  • [ ] NGS Mutation List: A list of genes tested (e.g., SF3B1, TET2, ASXL1, TP53).
  • [ ] Variant Allele Frequency (VAF): A percentage next to each mutation that shows how much of your marrow is affected by that specific “glitch” [17].
  • [ ] Classification Standard: Does the report mention “WHO 2022” or “ICC 2022” criteria? [18].

Common questions in this guide

What are the three pillars of a complete MDS pathology report?
A modern MDS pathology report should include morphology, cytogenetics, and molecular genetics. This means it must look at cell shapes under a microscope, map your chromosomes to look for structural changes, and scan your DNA for specific gene mutations.
What is the blast count and why does it matter for MDS?
Blasts are immature blood cells in your bone marrow. In MDS, they should typically be under 20 percent. If your blast percentage crosses this threshold, your diagnosis may change to Acute Myeloid Leukemia (AML).
What does a TP53 multi-hit mutation mean?
A multi-hit or biallelic TP53 mutation means both copies of the TP53 gene are altered. This is a high-risk finding that indicates a more aggressive form of myelodysplastic syndrome and can impact your risk score.
What does an SF3B1 mutation mean in myelodysplastic syndrome?
An SF3B1 mutation is typically considered a favorable finding in an MDS pathology report. It is often linked to ring sideroblasts and suggests the disease may progress more slowly.
Why is Next-Generation Sequencing (NGS) important for an MDS diagnosis?
Next-Generation Sequencing scans your DNA to identify the specific gene mutations driving your disease. Finding these genetic drivers helps your hematologist accurately score your risk level and determine the best targeted treatment plan.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Does my report include all three pillars: morphology, cytogenetics, and an NGS molecular panel?
  2. 2.What is the exact blast percentage, and how does it compare to the cutoff for AML in the classification system you are using?
  3. 3.If I have a TP53 mutation, is it 'single-hit' or 'multi-hit'? Why is that distinction important for my risk score?
  4. 4.How many chromosomal abnormalities were found in my karyotype—is it considered a 'complex karyotype'?
  5. 5.Do any of the mutations found, like SF3B1 or ASXL1, change which treatments are available to me right now?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (18)
  1. 1

    Molecular landscape of myelodysplastic neoplasms in disease classification and prognostication.

    Maggioni G, Della Porta MG

    Current opinion in hematology 2023; (30(2)):30-37 doi:10.1097/MOH.0000000000000752.

    PMID: 36728601
  2. 2

    Molecular monitoring of MDS: Watch this space!

    Scheid C

    British journal of haematology 2024; (205(3)):757-758 doi:10.1111/bjh.19644.

    PMID: 39039697
  3. 3

    Morphologic Characteristics of Myelodysplastic Syndromes.

    Yuen LD, Hasserjian RP

    Clinics in laboratory medicine 2023; (43(4)):577-596 doi:10.1016/j.cll.2023.06.003.

    PMID: 37865504
  4. 4

    Introduction to the Review Series on Myelodysplasia.

    Mittelman M

    Haematologica 2025; (110(2)):281-282 doi:10.3324/haematol.2023.284948.

    PMID: 39895333
  5. 5

    Where Does Morphology Fit in Myelodysplastic Syndrome Diagnosis in the Era of Molecular Testing?

    Giagounidis A, Haase S

    Hematology/oncology clinics of North America 2020; (34(2)):321-331 doi:10.1016/j.hoc.2019.11.005.

    PMID: 32089213
  6. 6

    Computational flow cytometry as a diagnostic tool in suspected-myelodysplastic syndromes.

    Duetz C, Van Gassen S, Westers TM, et al.

    Cytometry. Part A : the journal of the International Society for Analytical Cytology 2021; (99(8)):814-824 doi:10.1002/cyto.a.24360.

    PMID: 33942494
  7. 7

    TP53 mutation defines a unique subgroup within complex karyotype de novo and therapy-related MDS/AML.

    Weinberg OK, Siddon A, Madanat YF, et al.

    Blood advances 2022; (6(9)):2847-2853 doi:10.1182/bloodadvances.2021006239.

    PMID: 35073573
  8. 8

    Risk stratifying MDS in the time of precision medicine.

    Cazzola M

    Hematology. American Society of Hematology. Education Program 2022; (2022(1)):375-381 doi:10.1182/hematology.2022000349.

    PMID: 36485160
  9. 9

    Comparative Analysis of AML Classification Systems: Evaluating the WHO, ICC, and ELN Frameworks and Their Distinctions.

    Salman H

    Cancers 2024; (16(16)) doi:10.3390/cancers16162915.

    PMID: 39199685
  10. 10

    The Diagnostic Spectrum of Myelodysplastic Syndromes and Acute Myeloid Leukemia.

    Arber DA, Orazi A

    Advances in anatomic pathology 2025; (32(4)):299-306 doi:10.1097/PAP.0000000000000485.

    PMID: 39895485
  11. 11

    Single-cell spatial mapping reveals dynamic bone marrow microarchitectural alterations and enhances clinical diagnostics in MDS.

    Nachman R, Kopacz A, Unkenholz C, et al.

    bioRxiv : the preprint server for biology 2025; doi:10.1101/2025.10.02.680138.

    PMID: 41279873
  12. 12

    Transplant for TP53-mutated MDS and AML: because we can or because we should?

    Versluis J, Lindsley RC

    Hematology. American Society of Hematology. Education Program 2022; (2022(1)):522-527 doi:10.1182/hematology.2022000354.

    PMID: 36485102
  13. 13

    The Significance of Detecting an Unusual Myeloblast Immunophenotype in a Presumptive Clinical Diagnosis of Myelodysplastic Syndromes.

    Sameeta F, Wang W, Jelloul FZ, et al.

    Archives of pathology & laboratory medicine 2025; (149(8)):717-726 doi:10.5858/arpa.2024-0228-OA.

    PMID: 39711284
  14. 14

    [Mutational analysis of RNA splicing machinery genes SF3B1, U2AF1 and SRSF2 in 118 patients with myelodysplastic syndromes and related diseases].

    Wang JY, Ma J, Lin YN, et al.

    Zhonghua xue ye xue za zhi = Zhonghua xueyexue zazhi 2017; (38(3)):192-197 doi:10.3760/cma.j.issn.0253-2727.2017.03.004.

    PMID: 28395441
  15. 15

    SF3B1 Mutation but Not Ring Sideroblasts Identifies a Specific Group of Myelodysplastic Syndrome-Refractory Cytopenia With Multilineage Dysplasia.

    Xiong B, Xue M, Yu Y, et al.

    Clinical lymphoma, myeloma & leukemia 2020; (20(5)):329-339.e3 doi:10.1016/j.clml.2020.01.005.

    PMID: 32037286
  16. 16

    Risk prediction in MDS: independent validation of the IPSS-M-ready for routine?

    Baer C, Huber S, Hutter S, et al.

    Leukemia 2023; (37(4)):938-941 doi:10.1038/s41375-023-01831-1.

    PMID: 36725896
  17. 17

    Decoding the molecular drivers of TP53-mutant acute myeloid leukaemia: Clinical implications and prognostic insights.

    Wang LY, Gao HT, Fu Q, et al.

    British journal of haematology 2026; (208(2)):579-588 doi:10.1111/bjh.70271.

    PMID: 41320982
  18. 18

    Comparison of the International Consensus and 5th WHO edition classifications of adult myelodysplastic syndromes and acute myeloid leukemia.

    Falini B, Martelli MP

    American journal of hematology 2023; (98(3)):481-492 doi:10.1002/ajh.26812.

    PMID: 36606297

This page explains myelodysplastic syndrome (MDS) pathology terminology for educational purposes. Your hematologist or oncologist is the best source for interpreting your specific bone marrow biopsy report.

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