Director Tong Chunrong of Beijing Boren Hospital: A Full Analysis of Six Core Hematological Tests

Many family members of patients with hematological diseases share the same confusion during diagnosis: why are so many tests required? Blood draws, bone marrow punctures, repeated specimen submissions — what exactly does each detect? Can fewer tests be done? In fact, diagnosis of hematological diseases relies on comprehensive judgment from multiple examinations; a single test rarely delivers an accurate conclusion. Here, Director Tong Chunrong from Beijing Boren Hospital elaborates on the function, advantages and limitations of each core laboratory test.

Physicians order multiple tests not for redundant repetition, but because these technologies complement one another to form the basis for precise diagnosis. Clinical evaluation centers on five core laboratory divisions (naming varies across hospitals): Cell Morphology, Pathological Diagnosis, Flow Cytometry, Cytogenetics, and Molecular Diagnosis. Corresponding tests include cell morphology and cytochemical staining, pathology and immunohistochemistry, flow cytometry, karyotype analysis, FISH and gene testing.

Test 1: Cell Morphology & Cytochemical Staining

This is the most fundamental and rapid first step. Bone marrow or peripheral blood is smeared onto slides, stained, and examined under a microscope.

Advantages:

• Intuitive observation: abnormal cells can be identified at a glance to narrow differential diagnoses.
• Accurate cellular proportions: morphology uses the initial bone marrow aspirate with minimal processing and negligible hemodilution. Later tests often rely on second or third aspirate pulls, which may underestimate malignant cell proportion.
• Strong suggestive value: for example, abundant mitotic figures indicate rapid proliferation, prompting Ki-67 testing; smears may also reveal infectious pathogens.
• Cost-effective & rapid: preliminary results within 20–30 minutes at minimal cost.

Disadvantages: heavy reliance on the examiner's visual judgment and experience. For example, two morphologically similar populations may mimic lymphoma, yet the final diagnosis turns out to be hemorrhagic fever with renal syndrome (a viral infection). Inexperienced clinicians may misdiagnose and administer inappropriate lymphoma treatment.

Test 2: Pathology & Immunohistochemistry

While morphology assesses individual cells, pathology and immunohistochemistry analyze tissue blocks such as lymph node or mass biopsies fixed into paraffin sections.

Advantages:

• Complete specimen preservation: tissue is fixed in formalin upon collection, retaining information lost during other assays.
• Objective quantification of malignant cell percentage across whole-tissue sections.
• Diagnostic utility for inaccessible or rare cell populations: ideal for myelofibrosis, multiple myeloma, lymphoma (especially Hodgkin's), metastatic carcinoma, histiocytes, macrophages and dendritic cells.
• Direct visualization of tissue architecture: critical for lymphomas classified by characteristic tissue arrangements, such as mantle cell and follicular lymphoma — structures only visible on pathological slides.

Disadvantages:

• Prolonged turnaround and operator-dependent accuracy due to a lengthy fixation, embedding, sectioning and staining workflow.
• Limited ability to distinguish benign/malignant status in cases with intact architecture or low malignant burden.
• Sampling bias risk: malignant cells suspended in body fluids cannot be captured; false negatives occur if the biopsy misses tumor-infiltrated regions.

Test 3: Flow Cytometry (FCM)

Flow cytometry suspends isolated cells to pass single-file through the instrument, simultaneously detecting dozens of biomarkers on each cell.

Advantages:

• Rapid, comprehensive profiling: preliminary results within 2 hours; tens of thousands to hundreds of thousands of cells analyzed for over six parameters each, with high sensitivity.
• Clear differentiation of benign/malignant cells, maturation and lineage: for example, when two patients each show 8% blasts, morphology alone cannot distinguish regenerative normal blasts from residual leukemic blasts — flow cytometry readily can. This makes it the most widely used modality for minimal residual disease (MRD) monitoring.
• Identification of immunotherapy targets: markers including CD19, CD20 and BCMA confirm eligibility for CAR-T or antibody therapies; serial testing tracks treatment response and antigen loss.

Disadvantages:

• Loss of tissue architectural information after dissociation into single cells — critical for Hodgkin's lymphoma, which needs pathological correlation.
• Cell loss during processing: fragile populations such as diffuse large B-cell lymphoma (DLBCL) blasts and immature erythroid cells may rupture, underreporting tumor percentages. Morphology is superior for erythroleukemia (M6) and myelodysplastic syndromes (MDS).
• Strict specimen timelines: samples must be processed within 4 hours.
• High technical expertise threshold; less prognostic value than karyotyping and gene sequencing.

Test 4: Chromosome Karyotype Analysis

Karyotyping microscopically evaluates numerical and structural chromosomal abnormalities (aneuploidy, translocations).

Advantages:

• Independent diagnostic and prognostic value: certain aberrations are definitive criteria — the Philadelphia chromosome (9;22 translocation) for chronic myeloid leukemia (CML), and the 15;17 translocation for acute promyelocytic leukemia (APL/M3). Profiles also stratify patients into favorable, intermediate and high-risk subgroups.
• Detection of uncharacterized lesions: karyotyping provides a genomic "panoramic view."

Disadvantages:

• Long turnaround: cell culture is required, with results in 7–14 days.
• Heavy reliance on technician expertise for manual band interpretation.
• False negatives from non-proliferative malignant cells that fail to divide in culture.
• Low analytical sensitivity: malignant populations below 5–10% are easily missed, making it unsuitable for MRD surveillance.

Test 5: FISH (Fluorescence In Situ Hybridization)

FISH is a high-resolution refinement of karyotyping, using fluorescent-labeled probes against specific chromosomal or gene loci.

Advantages:

• Independent diagnostic and prognostic utility, confirming canonical aberrations.
• Detection of submicroscopic lesions invisible to conventional karyotyping.
• Mitosis-independent detection of interphase cells without cell culture.
• High sensitivity via large cell counting pools, superior MRD sensitivity versus karyotyping.
• Rapid turnaround (1–2 days) with objective, countable signals.
• Retrospective testing on archived smears and paraffin blocks.

Disadvantages:

• High probe cost; each assay typically evaluates only 1–2 predefined abnormalities.
• Only detects known aberrations — the core distinction from karyotyping's whole-genome screening.

Test 6: Gene Sequencing / Molecular Testing

The most granular tier, evaluating DNA and RNA abnormalities including mutations, fusion transcripts and aberrant expression.

Advantages:

• Independent diagnostic and prognostic value: recurrent lesions (e.g., NPM1 mutation, double CEBPA mutation) are definitive markers enabling precise risk stratification.
• Detection of lesions invisible to karyotyping and FISH. Combining karyotype, FISH and molecular testing drastically improves prognostic accuracy.
• Faster turnaround than karyotyping (1–2 weeks).
• Reduced operator dependency via standardized workflows.
• Gold-standard high-sensitivity MRD monitoring: quantitative PCR or next-generation sequencing detects residual disease down to 1 in 10,000 to 1 in 100,000 cells.

Disadvantages:

• Stringent quality control across all stages; results are vulnerable to error in multistep workflows and massive datasets.
• Limited utility for genetically wild-type malignancies without characterized driver mutations, which require complementary testing.

Conclusion

Are these six core examinations sufficient? Beyond the six MICM integrated diagnostic assays, two additional assessments support full-cycle management: pathogen testing (identifying bacterial, viral such as EBV, and other agents) and therapeutic drug monitoring with pharmacogenomic testing (enabling personalized regimens).

Crucially, no single test can independently resolve all clinical questions. Multidimensional integrated analysis enables clinicians to accurately stage disease and formulate individualized treatment plans. Understanding the purpose and limitations of each assay helps patient families approach diagnosis and treatment with greater composure and rationality.