Abstract
Selection of the appropriate ancillary tests, often based on careful morphologic examination of peripheral blood and bone marrow and adequate patient data, are critical for accurate diagnosis. Sometimes a characteristic clinical picture or pathognomonic morphologic feature directly reflects the need for a specific panel applied simultaneously with the initial examination. Routine ancillary tests range from cytochemical and histochemical staining to more complex immunophenotyping, genetic, and molecular techniques. Sample processing and laboratory conditions affect the accuracy and reliability of these tests. The technical test procedure, interpretation, quality control measure, and source of error are essential considerations discussed for each test category in this chapter.
TopIntroduction
Careful morphologic examination of the bone marrow will often suggest one or more ancillary tests to confirm the diagnosis, exclude differential diagnoses, or assess prognostic factors. A characteristic clinical picture or a previous diagnosis may indicate a simultaneous ancillary test application at the initial examination. These tests encompass technical procedures applied to specific sample preparation, including aspirate smears, biopsy touch imprints, clot sections, and paraffin-embedded cores.
Ancillary tests involve cytochemical and histochemical stains, immunophenotyping, and genetic and molecular tests. The proper selection of the test panel requires a deep knowledge of the disease pathology and diagnostic criteria and the professional skill for the appropriate application of the technique, its interpretation, recognition of its diagnostic specificity and sensitivity, and test limitations.
Some tests are integral within the bone marrow pathology laboratory, e.g., cytochemical and histochemical tests and IHC, while others require specialized units such as flow cytometry and molecular tests. In the latter case, careful attention to the type and quality of the sample is critical. This chapter will give an overview of the main ancillary test applied in bone marrow diagnosis:
- 1.
The categories of ancillary tests
- 2.
The rationale for test application, standard technique, limitations, and interpretation
- 3.
The quality control and assurance measures applied to the test
TopCategories And Applications Of Ancillary Tests For Bone Marrow Diagnosis
The ancillary test can identify cell type and differentiation stage, microorganisms, or abnormal deposition in the bone marrow cells or stroma.
They can be applied to bone marrow aspirate smear, anticoagulated sample, or bone marrow biopsy and are significantly affected by the initial sampling and processing protocols. It is, therefore, essential to determine all test requirements before commencing sampling.
Key Terms in this Chapter
Chromosome Painting: Refers to the fluorescent tagging of chromosome-specific dna sequences for the visualization of specific chromosomes or dna segments.
Omic Methods: All the processes of cell or tissue analysis, including single nucleotide polymorphisms (SNP) and comparative genomic hybridization array (aCGH), transcriptional genomics, gene expression profiling, and proteomics, which represent the totality of events in the cell/tissue.
Break Apart FISH Probes: Dual-color probes; each corresponding to one end of the gene used to detect gene rearrangements when the two probes split and appear as two unique signals.
Gene Expression Profiling: A method used to measure expressed genes transcriptional mRNAs in a cell or at a particular time to determine genetic markers for targeted therapy in neoplastic diseases. DNA microarrays or sequencing technologies can measure thousands of genes in one reaction.
Machine Learning (ML) And Artificial Intelligence (AI) In Bone Marrow Diagnosis: A.I. is a subdomain of ML, which refers to the automatic detection of patterns and associations leading to faster generation of high-quality data for a fraction of the original costs, and increased availability of digital data. It has increasing applications in hematology diagnosis, including cytomorphology, cytogenetics, immunophenotyping, and molecular genetics.
Next-Generation Sequencing (NGS) in Hematologic Diagnosis: The NGS techniques facilitate the identification of structural genetic variations, such as deletions/insertions, inversions, substitutions, and translocations, and potentially provide an accurate diagnostic tool overcoming the limitations of conventional DNA sequencing. They include whole-exome sequencing (WES), whole-genome sequencing (WGS), and targeted gene sequencing. The latter provides superior and in-depth sequencing than WES/WGS and simultaneously allows for mutation detection in over 100 genes.