Introduction to Pathology Flashcards
What is pathology the study of?
Suffering - study of disease and cellular dysfunction
Where can serous carcinoma occur?
Ovary, fallopian tube, uterus, cervix, peritoneum
What is autolysis?
Tissue self-destruction that begins when blood supply is cut off
How can we block the chemical process of autolysis?
By using fixatives
What do fixatives do?
Inactivate tissue enzymes and denature proteins, prevent bacterial growth, harden tissue
What is an example of a commonly used fixative?
Formalin (formaldehyde in water) - usually fix for 24-48 hours
What do we do to tissues after they have been fixed?
Cut up, samples are taken - about size of stamp - and placed into a cassette and placed in racks in formalin
Why do tissues have to be hardened?
In order to be able to cut very thin sections
What is used as a hardening agent?
Paraffin wax
Why is alcohol and xylene used in tissue preparation?
Alcohol removes the water and xylene removes the alcohol
What is used to cut tissue samples into very thin sections?
Microtome
What does haematoxylin stain?
Nuclei purple
What does eosin stain?
Cytoplasm and connective tissue pink
What is immunohistochemistry?
Demonstrates substances in/on cells by labelling them with specific antibodies - usually joined to an enzyme eg peroxidase that catalyses a colour-producing reaction
What can immunohistochemistry of the Her2 receptor predict?
Response of breast cancer to Herceptin
If a carcinoma is CK7+ and CK20- what could be the primary site?
Lung, breast, endometrium, ovary, thyroid
If a carcinoma is CK7- and CK20+ what could be the primary site?
Large bowel, some gastric carcinomas
How can sequencing of DNA purified from tumour tissue be useful?
Eg if certain mutations in EGFR gene are present in lung cancer then the tumour is likely to respond to anti-EGFR treatments eg erlotinib
Why is it better to look at mRNA expression over DNA sequencing?
Tells you whether the genes are being transcribed
Why are frozen sections not routinely used?
Morphology not as good, more likely to make errors
What can be used as a marker to identify smooth muscle cells?
Contractile protein actin
What does the presence of cytokeratins demonstrate?
Epithelial differentiation
Different cytokeratins show tissue-specific distribution
How long does it take for a result of a frozen section from receipt of the tissue in the lab?
About 10 minutes
