Bone Marrow Evaluation
Systematic approach to BM interpretation
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PathologyDiagnostic
Bone Marrow Biopsy Systematic Interpretation
Bone Marrow Biopsy Systematic Interpretation: Bone Marrow Evaluation → Specimen Assessment → Cellularity Assessment → Trilineage Assessment → Dysplasia ...
Pathway Overview
10 steps
Algorithm Steps
10 total
01Start 02Action Specimen Assessment
Evaluate adequacy
- Core biopsy length (≥1.5 cm)
- Aspirate quality (spicules present)
- Touch prep available
- Flow cytometry specimen
- Cytogenetics/molecular specimen
03Action Cellularity Assessment
Age-adjusted (100-age = expected %)
- Hypercellular, normocellular, hypocellular
- Distribution: patchy vs diffuse
- Consider aplastic anemia if very hypocellular
- Consider MPN if hypercellular with fibrosis
04Action Trilineage Assessment
Erythroid, myeloid, megakaryocyte
- M:E ratio (normal 2:1 to 4:1)
- Erythroid maturation and dysplasia
- Myeloid maturation and dysplasia
- Megakaryocyte number and morphology
- Left shift or maturation arrest
05Decision Dysplasia Assessment
≥10% in lineage = significant
- Erythroid: nuclear irregularity, megaloblastoid, ring sideroblasts
- Myeloid: hypogranulation, pseudo-Pelger-Huet
- Megakaryocyte: micromegakaryocytes, hypolobation
- Multilineage dysplasia supports MDS
06Action Integrated Diagnosis
Correlate all findings
- Clinical history and CBC
- Flow cytometry results
- Cytogenetics/FISH
- Molecular studies (NGS if available)
- WHO 5th Edition classification
07Outcome Final Report
Synoptic format with diagnosis, staging if applicable
08Decision Blast Assessment
Aspirate differential
- Count on aspirate (500 cells)
- CD34 IHC on biopsy if needed
- <5% normal
- 5-9% MDS with excess blasts-1
- 10-19% MDS-EB2
- ≥20% Acute leukemia
09Action Fibrosis Grading
Reticulin/trichrome staining
- MF-0: Scattered linear reticulin
- MF-1: Loose network, no collagen
- MF-2: Diffuse, coarse reticulin ± collagen
- MF-3: Coarse reticulin with collagen bundles
- Suggests MPN if grade 2-3 with megakaryocyte atypia
- Path rejoins step 06Shared downstream outcome
10Action Abnormal Populations
Identify infiltrates
- Plasma cells: CD138 for quantification
- Lymphoid aggregates: assess clonality
- Metastatic carcinoma: CK, site-specific markers
- Granulomas: infectious or immune
- Mast cells: CD117, tryptase
- Path rejoins step 09Shared downstream outcome
Guideline Source
WHO Classification and CAP Bone Marrow Guidelines
Clinical Safety Information
Clinical Decision Support — Not a Substitute for Clinical Judgment
Individual patient factors may require deviation from these recommendations.
Known Limitations
- Requires integration with clinical, lab, flow, and cytogenetics
- Some diagnoses need molecular confirmation
- Specimen adequacy affects interpretation
- WHO classification evolves
- Staging may require specific IHC
Applicable Regions
USAUUKEU
AU: RCPA bone marrow standards
UK: BCSH bone marrow guidelines
US: CAP synoptic reporting templates
Version 1Next review: 2028-01-01
Next steps
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Related Resources
Frequently Asked Questions
What is the Bone Marrow Biopsy Systematic Interpretation?
The Bone Marrow Biopsy Systematic Interpretation is a diagnostic clinical algorithm for Pathology. It provides a structured decision tree to guide clinical decision-making, based on WHO Classification and CAP Bone Marrow Guidelines.
What guideline is the Bone Marrow Biopsy Systematic Interpretation based on?
This algorithm is based on WHO Classification and CAP Bone Marrow Guidelines (DOI: 10.1182/blood-2016-03-643544).
What are the limitations of the Bone Marrow Biopsy Systematic Interpretation?
Known limitations include: Requires integration with clinical, lab, flow, and cytogenetics; Some diagnoses need molecular confirmation; Specimen adequacy affects interpretation; WHO classification evolves; Staging may require specific IHC. Individual patient factors may require deviation from these recommendations.
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