Approach to Newly Diagnosed AML
For a newly diagnosed AML case, immediately obtain a bone marrow aspirate with core biopsy and send samples for morphologic evaluation, conventional cytogenetic analysis (karyotype), molecular genetic testing (including FLT3, NPM1, IDH1/2, and other relevant mutations), and flow cytometry immunophenotyping—all performed simultaneously to enable rapid risk stratification and treatment planning. 1
Initial Clinical Assessment
Provide the pathologist with comprehensive clinical data including:
- Patient demographics: Age, sex, ethnicity
- Disease history: Prior hematologic disorders, predisposing syndromes, previous malignancies
- Exposure history: Cytotoxic therapy, immunotherapy, radiotherapy, toxic substances
- Confounding factors: Recent growth factors, transfusions, medications that may obscure morphology
- Family history: Hematologic disorders or malignancies (critical for identifying germline predisposition)
- Physical examination findings: Neurologic status, tumor masses (mediastinal), cutaneous lesions, organomegaly 1
Diagnostic Workup Algorithm
1. Peripheral Blood Evaluation (Immediate)
- Complete blood count with differential
- Peripheral blood smear review by pathologist 1
2. Bone Marrow Sampling (Urgent—Same Day)
Obtain fresh bone marrow aspirate for:
- Morphologic smears
- Flow cytometry immunophenotyping
- Conventional cytogenetics (karyotype)
- Molecular genetic testing
- FISH studies
Obtain adequate core biopsy with:
- Touch preparations
- Trephine sections
- Consider second core in tissue culture medium if aspirate inadequate (for disaggregation for flow/genetics) 1
Critical caveat: If bone marrow aspirate is unobtainable ("dry tap"), peripheral blood can substitute if sufficient blasts present, or use touch imprints from core biopsy 1
3. Mandatory Ancillary Testing (Strong Recommendations)
Conventional cytogenetics (karyotype): This is non-negotiable and cannot be replaced by molecular testing alone—it identifies complex karyotypes, balanced translocations, and chromosomal abnormalities critical for risk stratification 1
Molecular genetic testing must include at minimum:
- FLT3 (ITD and TKD mutations)
- NPM1
- IDH1 and IDH2
- DNMT3A, TET2, RUNX1, NRAS, TP53 (commonly altered genes)
- Consider comprehensive NGS panel for full mutational profiling 2, 3, 4
Flow cytometry immunophenotyping: Panel must distinguish AML from APL, T-ALL, B-ALL, and acute leukemia of ambiguous lineage. Ensure comprehensive enough for subsequent measurable residual disease (MRD) monitoring 1
FISH testing: Supplements but does not replace karyotype 1
4. Additional Diagnostic Procedures
For ALL or high-risk presentations: Obtain CSF sample with cell count and cytocentrifuge preparation for blast enumeration 1
For extramedullary disease: Tissue biopsy processed for morphology, immunophenotyping, cytogenetics, and molecular studies—may require additional biopsies for fresh material 1
Cytochemical studies: May assist in AML classification (expert consensus opinion) 1
5. Specimen Preservation (Critical for Future Studies)
Store pretreatment samples:
- Nucleic acids (DNA/RNA at -80°C)
- Viable cells (at -196°C)
- Germline DNA (buccal swab, skin biopsy)
- Plasma sample
- Fixed cell pellet from cytogenetics 5
Risk Stratification Framework
Once diagnostic results return, apply ELN 2022 genetic risk classification which integrates:
- Cytogenetic findings (favorable: core binding factor AMLs; adverse: complex karyotype, monosomal karyotype, specific translocations)
- Molecular mutations (favorable: NPM1 mutation without FLT3-ITD or with low allelic ratio; adverse: TP53, RUNX1, ASXL1 mutations)
- Secondary AML features
- Patient age and comorbidities 2, 4
Common Pitfalls to Avoid
Do not rely on FISH or molecular testing alone—conventional karyotype is mandatory for detecting complex karyotypes and balanced translocations 1
Ensure adequate sample collection upfront—insufficient material delays diagnosis and treatment. If aspirate is inadequate, immediately obtain second core biopsy in tissue culture medium 1
Do not forget germline testing considerations—certain mutations (TP53, RUNX1, CEBPA, DDX41) may indicate hereditary predisposition requiring family screening 6
Distinguish APL immediately—if morphology suggests acute promyelocytic leukemia, initiate ATRA empirically while awaiting PML-RARA confirmation, as this is a medical emergency 1
Plan for MRD monitoring from diagnosis—ensure flow cytometry and molecular assays are comprehensive enough to track disease during treatment 1, 4, 7
Coordination with Pathology
The same physician should ideally interpret both aspirate smears and core biopsy, or interpretations must be correlated if performed by different pathologists. Ensure pathologist has immediate access to all clinical data and imaging results 1