Histopathology & cytopathology Flashcards
What is histopathology?
The study of tissues.
What is cytopathology?
The study of cells.
What diagnostic methods are involved in histopathology? (x4)
Biopsies, resection specimens, frozen sections and post-mortems.
What diagnostic methods are involved in cytopathology? (x2)
Smears and fine needle aspirates.
What is fine needle aspiration?
Thin, hollow needle is used to take a sample of cells from an organ or lump under the skin (esp. lymph node). The cells are then analysed under a microscope.
What are biopsies used to tell us? (x3)
Is a tissue normal? Inflamed and, if it is, what is the cause? Is it cancer and, if it is, what type is it?
What are resection specimens?
Tissue specimens are obtained by the surgical removal of an entire diseased area or organ e.g. removal of colon in colon cancer.
What are resection specimens tested for in histopathology? (x2)
Study how far the cancer has spread? Is the tumour/disease been completely removed? You determine whether a tumour/disease has been completely removed by assessing the margins of the resection (see photo). If there is cancer/disease present at the margins, then the cancer/disease is unlikely to have been completely removed. There would still be some cancer/disease at the anastomose and potentially beyond.
What is a frozen section?
Surgical specimen is cut to a very thin slice, then frozen and embedded in gel medium to harden. Sections can be stained, antigens identified with antibodies and molecular tests performed. Then it is ready for examination under a microscope.
What is frozen section used for in histopathology? (x3)
(1) It is used for RAPID diagnosis – differentiate between benign and malignant cells. (2) Identify if a resection margin is clear of cancer. (3) Identify presence of antigens with antibodies – used in diagnosis of cancers etc.
What are the advantages of frozen section? (x2)
It is very RAPID. In addition, tumours are clearly either benign or malignant in frozen section.
What are the two-types of post-mortem?
Hospital (requested by clinician to understand why patient died) and coroners (suspicious circumstances).
How are specimens processed in histopathology?
- Biopsy arrives in labelled pot with name, DOB and number. 2. Tissue is fixed in formalin (formaldehyde in water) – tissue preservative to allow for easier examination. It has low penetration into the tissue (penetrates 1mm per hour), so does not alter the tissue very much. 3. Tissue is embedded in paraffin wax. 4. Microtome is used to cut sections from the paraffin block (between 4-5um in width). 5. Studied under the microscope and labelled correctly.
How can tissue sections be studied? (x3)
□ Stain e.g. gram staining. □ Identify specific antigens using antibodies = immunochemistry. □ Carry out molecular tests.
What is immunochemistry used for?
Diagnosis of abnormal cells e.g. tumours (certain molecular markers can be found on cell surfaces which indicate proliferation and apoptosis).
