S1 L1 Flashcards
What is pathology?
Study of suffering
What is medical microbiology?
The study of microorganisms such as bacteria, viruses, fungi, and parasites. It aims to understand their role in disease and symptom presentation.
What is chemical pathology?
Biochemical investigations of disease =combines clinical skills with laboratory work. Chemical pathologists use biochemical tests to diagnose disease and to manage patients
Describe the haematology pathology discipline
study and treatment of diseases of the blood.
Describe the immunology pathology discipline
This branch of pathology is concerned with the immune process of the body.
Describe the Histopathology and cytopathology pathology discipline
Histopathology is the study of the cellular changes within tissues that are caused by disease. Cytopathology is a diagnostic technique that examines sampled cells from various body sites to determine the cause or the nature of disease. e.g. pap smear test
Describe the histology technique for obtaining samples for diagnostic microscopy
Histology will involve the removal of a tissue sample to be able to assess both tissue and cell morphology.
examples: core biopsies, cancer resection specimens
Describe the cytology technique for obtaining samples for diagnostic microscopy
Cytology involves taking samples of free cells separate from the structure of the tissue often obtained by fine-needle aspiration.
Cytology is cheaper, faster, and less invasive than a histological sample, however also has higher rates of error.
It be used before histology as a preliminary test.
what questions does a histopathologist ask to arrive at a diagnosis?
Is the sample normal or abnormal?
Is it inflammatory or neoplastic?
Is it benign or malignant?
Is it a primary tumour or a metastasis?
What can a histopathologist tell us about a diagnosis of cancer?
type of cancer grade of cancer stage of cancer completeness of excision and if margins are involved which ones likely efficacy of further treatments
What happens in fixation?
The preservation of biological tissues from decay due to autolysis or putrefaction.
Usually formalin (formaldehyde in water) is used, and the process can take up to 48 hours.
What happens in the cut-up section of producing a histological report?
The tissues are cut up and placed into a cassette and then placed in racks of formalin (a solution containing formaldehyde which fixes cells by cross-linking proteins).
describe the process of embedding
samples are dehydrated using alcohol in a vacuum to dehydrate the cells. The alcohol is then replaced with xylene (which can mix with wax). The xylene is finally replaced with molten paraffin wax, which will permeate the cells to fix them.
describe the process of blocking
The embedded tissues are removed from their cassettes and put into metal blocks, which are then filled with more molten paraffin wax.
The wax is allowed to cool and the metal tray is moved. The tissues are now embedded in blocks of wax and are hard enough to be cut
describe the process of microtomy
The blocks are cut into very thin sections using a machine called a microtome. The sections are 3-4 microns thick, which is thin enough to be seen through with a light microscope.
describe the process of staining
Staining is usually done with two chemicals: Haematoxylin and Eosin (H&E staining). Haematoxylin stains nuclei purple and eosin stains the cytoplasm and connective tissues pink.
describe the process of mounting
A mountain medium is applied to the slide, followed by the sample and then a coverslip. The mounting medium will dry and harden, preserving the tissue and firmly attaching the coverslip.
what happens after mounting in the process of producing a histopathology report?
Microscopy
The slides are ready to be analysed by a clinician
Report writing
Reports will follow a format of: Clinical history, macroscopic appearance, microscopic appearance, and conclusion.
describe the process of immunhistochemistry
demonstrates substances in/on cells by labelling them with specific antibodies
usually Ab is joined to an enzyme that catalyses a colour-producing reaction
highlights the substances usually with a brown colour
what are cytokeratins?
family of intracellular fibrous proteins
present in almost all epithelia
at least 20 known
= markers for epithelial differentiation and show tissue-specific distribution in epithelia
can give info about primary site of a carcinoma
what is molecular pathology?
studies how diseases are caused by alterations in normal cellular molecular biology
=can be due to altered DNA, RNA or protein
how can we test cellular DNA?
In situ molecular tests show how DNA is altered in cells
DNA sequencing purified from tumour tissue can show if a particular point mutation is present in a particular gene
what can mRNA expression profiling methods demonstrate?
the level of activity of a large number of genes simultaneously
mRNA expression signatures can predict how a given tumour is likely to behave
What are frozen sections?
Histological preparations used in case of urgency.
A cryostat will be used to rapidly freeze a section and skip the embedding process. From receiving a specimen to giving a result it takes roughly 10 minutes.
Aim is to establish presence and nature of a lesion and influence the course of the operation
What are the negatives of frozen section?
cell morphology less well presevered and not easy to interpret
96% accurate= errors due to misinterpretation
lesion of interest not present in the tissue submitted for frozen section
