Why are supplementary tests needed in Histology?
Histology involves the study of tissues under the microscope to diagnose diseases. While routine staining techniques like Hematoxylin and Eosin (H&E) provide a wealth of information, they may not always be sufficient to reach a definitive diagnosis. Supplementary tests are employed to enhance the diagnostic accuracy, helping pathologists identify specific cellular and molecular characteristics of tissues.
Immunohistochemistry (IHC): Utilizes antibodies to detect specific antigens in tissue sections, aiding in the identification of particular cell types or disease markers.
Special Stains: Such as Periodic Acid-Schiff (PAS) or Masson's Trichrome, which highlight specific tissue components like carbohydrates and collagen, respectively.
In Situ Hybridization (ISH): Detects specific nucleic acid sequences within tissues, useful for identifying viral infections or genetic abnormalities.
Molecular Pathology: Techniques like Polymerase Chain Reaction (PCR) and Next-Generation Sequencing (NGS) analyze genetic material to identify mutations, translocations, or other genetic alterations.
Flow Cytometry: Often used for hematologic malignancies, this technique analyzes the physical and chemical characteristics of cells in a fluid suspension.
When routine H&E staining is inconclusive.
To differentiate between neoplastic and non-neoplastic lesions.
To identify specific types of cancer and their subtypes.
For the detection of infectious agents that are not easily visible with standard stains.
To determine the molecular profile of a tumor, which can guide targeted therapy.
Immunohistochemistry can confirm the presence of specific proteins that are characteristic of certain cell types or disease states.
Special stains can reveal structural details not visible with standard H&E staining, such as fungal organisms or amyloid deposits.
In Situ Hybridization can pinpoint the exact location of genetic abnormalities within the tissue context.
Molecular pathology techniques can identify genetic mutations that may be driving a disease and suggest potential therapeutic targets.
They can be expensive and time-consuming.
False positives or negatives can occur, requiring careful interpretation.
Not all laboratories may have the necessary equipment or expertise to perform certain tests.
Some tests, such as molecular techniques, may require high-quality tissue samples, which can be challenging to obtain.
Pathologists review the supplementary test results in conjunction with histological findings from routine staining.
A detailed report is generated, summarizing all findings and providing a comprehensive diagnosis.
In complex cases, a multidisciplinary team meeting (MDT) may be held, involving specialists from various fields to discuss the case and reach a consensus diagnosis.
Conclusion
Supplementary tests are indispensable tools in histology, significantly enhancing the accuracy and specificity of diagnoses. They provide critical insights that go beyond what is visible under the microscope with routine staining, aiding in the precise identification and characterization of diseases. However, their use should be judicious, taking into account their limitations and the context of each individual case.
