What is a basic leukemia panel test?

What is a Basic Leukemia Panel Test

A basic leukemia panel test is a comprehensive diagnostic workup that includes peripheral blood and bone marrow examination with complete blood count, morphologic assessment, multicolor flow cytometry immunophenotyping, conventional cytogenetics, and molecular genetic testing to establish the diagnosis and classification of acute leukemia. 1

Core Components of the Basic Panel

Initial Laboratory Studies

• Complete blood count (CBC) with differential on peripheral blood, including manual differential count and blood smear review using May-Grünwald-Giemsa or Wright-Giemsa stain counting at least 200 leukocytes 1, 2, 3
• Comprehensive metabolic panel, lactate dehydrogenase, phosphate, and uric acid levels to assess for tumor lysis syndrome risk 1, 2
• Coagulation panel including prothrombin time, partial thromboplastin time, and fibrinogen activity to detect early disseminated intravascular coagulation, particularly in acute promyelocytic leukemia 1

Morphologic Examination

• Bone marrow aspirate and core biopsy with examination of at least 500 nucleated cells on marrow smears containing spicules, including touch imprint preparations and cell clots 1, 4, 2
• Peripheral blood examination can substitute for bone marrow if sufficient blasts are present (≥20% for most AML diagnoses) or if bone marrow biopsy is contraindicated or yields a dry tap 1, 4

Immunophenotyping

• Multicolor comprehensive flow cytometry panel (8-10 colors minimum) performed on bone marrow aspirate or peripheral blood to distinguish myeloid, lymphoid, or mixed phenotype acute leukemia 1, 4
• Flow cytometry should cover markers for B-cell ALL (CD19, CD10, CD20), T-cell ALL (CD3, CD5, CD7), and AML (CD13, CD33, CD117, myeloperoxidase) 1, 2
• Additional flow cytometry on bone marrow is unnecessary if a diagnostic flow study has already been performed on peripheral blood with sufficient blasts 1

Cytogenetic Analysis

• Conventional karyotyping is mandatory and must be performed on bone marrow with analysis of a minimum of 20 metaphase cells to establish normal karyotype 1, 4, 2
• FISH studies should be performed according to the suspected leukemia subclassification (e.g., rapid FISH for PML-RARA if acute promyelocytic leukemia is suspected, BCR-ABL1 for Philadelphia chromosome-positive ALL) 1, 2

Molecular Genetic Testing

• Molecular studies are selective based on leukemia subtype, including PCR, RT-PCR, immunoglobulin/T-cell receptor gene rearrangements, fusion transcripts, or next-generation sequencing 1, 2
• For acute myeloid leukemia with normal cytogenetics, mandatory testing includes NPM1, CEBPA, and FLT3 mutations 4
• Additional molecular markers may include FLT3-ITD, IDH1, IDH2, TET2, WT1, DNMT3A, TP53, RUNX1, and KIT depending on the specific AML subtype 1, 4

Algorithmic Approach to Testing

When Peripheral Blood Shows Sufficient Blasts

Perform manual differential count, flow cytometry, FISH, and molecular studies directly on peripheral blood without waiting for bone marrow results, as this can expedite diagnosis when the patient is clinically unstable or bone marrow aspiration yields a dry tap 1

When Complete Ancillary Studies Are Available

No additional biopsy of extramedullary tumor is necessary when a complete panel has been performed on positive peripheral blood or bone marrow samples; repeat biopsy is only required when both peripheral blood and bone marrow are uninvolved 1

Cytochemical Studies

Myeloperoxidase and nonspecific esterase staining may be performed on bone marrow or peripheral blood for diagnosis and subclassification of AML, particularly when flow cytometry resources are limited 1, 2

Critical Timing Considerations

Basic diagnostics with at least cytomorphology and flow cytometry should be reported within 48-72 hours after preliminary diagnosis to allow treatment initiation 1

A complete final comprehensive report including all available risk factors should be issued within 1 week, or extended to 2 weeks maximum when all ancillary test results are available 1

Common Pitfalls to Avoid

• Recent growth factor therapy, transfusions, or certain medications can obscure or mimic features of acute leukemia, so document these exposures before interpreting results 3
• Do not rely solely on peripheral blood when bone marrow examination is feasible, as bone marrow provides superior material for cytogenetic and molecular studies 2
• Preleukemic clones (frequently DNMT3A, ASXL1, and TET2) can persist during therapy but are not reliable markers for minimal residual disease monitoring 1