Lecture 8 - Applications of Molecular Diagnostics Flashcards
How does in-situ hybridization (ISH) contribute to the detection of viruses in pathology?
ISH helps identify viruses, like high-risk human papillomaviruses (hrHPV), associated with cancers such as cervical carcinoma.
Explain the significance of distinguishing between HPV-positive and HPV-negative head and neck cancers in pathology.
Distinguishing HPV status is crucial for planning therapy, as HPV-positive tumors generally have a better prognosis than HPV-negative ones.
In cervical screening, why is there no screening under the age of 25, and why is there no screening over the age of 65 for women with clear screens?
Abnormalities are common under 25 but often regress. Over 65, women with three clear screens have minimal cancer risk.
How does in-situ hybridization contribute to the post-transplant lymphoproliferative disease (PTLD) diagnosis, especially when associated with Epstein-Barr virus (EBV) infection?
ISH helps identify EBV in PTLD cases, assisting in diagnosis and guiding therapeutic decisions by assessing the viral involvement.
What key histological features are analyzed in breast cancer pathology, and why is the presence or absence of myoepithelial cells significant?
Analysis involves abnormal ducts, and myoepithelial cells indicate in situ disease (ductal carcinoma in situ - DCIS) or invasive ductal carcinoma if absent.
Name the immunocytochemistry markers used to identify myoepithelial cells in breast cancer pathology.
SMM (smooth muscle heavy chain), P63 (transformation-related protein 63), MNF116 (broad-spectrum cytokeratin), and SMA (smooth muscle actin).
Why is assessing HER2 status important in breast cancer, and how is it done using ICC and ISH?
HER2 status guides the use of drugs like Herceptin. ICC and ISH are used to assess HER2 gene amplification and receptor overexpression.
Explain the role of cytopathology in breast cancer, distinguishing between screening and diagnostic applications.
Cytopathology serves as a screening tool for cervical cytology screening and aids in diagnostic cytology, collecting samples without solid tissue.
What are the fixation requirements for cytology specimens, and why is fixation essential?
Specimens must be fixed to prevent autolysis. Ethanol is a common non-additive fixative, stabilizing nucleic acids and chromatin.
Describe the techniques used for producing thin and evenly spread smears in cytopathology.
Techniques include blood smear and squash technique for thin smears, and centrifugation for concentrating and enriching cells.
What is the significance of the Papanicolaou stain in cytopathology, and what does it specifically stain?
The stain highlights nucleus (haematoxylin), keratin (Orange G), and cytoplasm (Eosin azure), aiding in the identification of cellular abnormalities.
How do Romanowsky stains contribute to air-dried cell staining in cytopathology?
Romanowsky stains, like Giemsa and Wright, produce the Romanowsky effect, staining nuclei purple, cytoplasm blue, and red blood cells pink.
What stains are suitable for investigating microorganisms, particularly fungi, in cytopathology?
The Grocott stain, utilizing silver impregnation, is used for investigating fungi, especially opportunistic pathogens like Pneumocystis jiroveci.
Explain the process and significance of Grocott staining in cytopathology for investigating fungi.
Grocott stain involves chromic acid oxidation, methenamine silver incubation, and light green counterstaining, aiding in the identification of fungi.
How does cervical cytology screening contribute to cancer prevention, and what is the rationale for screening at specific ages?
Cervical cytology screening detects changes early, preventing invasive carcinoma. Screening starts at 25, focusing on high-risk age groups, and ceases after 65 for low-risk individuals.
