Session 1 Flashcards
What is pathology?
Pathology is a bridging discipline betweens cience and clinical practice.
- investigates the changes (structural and functional) in cells, tissues and organs that are seen in disease.
- study of disease and cellular malfunction
- the ultimate abnormality always lies in the cell
What did Rudolf Virchow do that has helped study pathology so much?
- he discredited the theory of 4 humours
- he said that all cells come from cells, and that the body is a society of living cells, a tiny well-ordered state, with all the accessories - high officials and underlings, servants and masters…
- “pathology is histology with obstacles”
Why are cells called cells and who named them?
Robert Hooke named them cells, as when he looked down his primitive microscope at a slice of cork, he thought the compartments looked like monk cells.
In all physical disease, the … is considered the central player.
cell
Disease can be considered to be a consequence of failed …
homeostasis
What is pathology?
The study of suffering
ie the study of disease and cellular dysfunction (as opposed to biology that studies life and cellular function)
Which are the disciplines of pathology? (5)
- Chemical pathology (clinical biochemistry)
- Haematology - diseases of blood, blood clotting, blood transfusion, bonen marrow transplant
- Cellular pathology (histopathology and cytopathology) - examines organs, tissues and cells for diagnosis and to guide treatment, often cancer work.
- Immunology - diseases of the immune system
- Medical microbiology - disease-causing microbes including advice on antibiotic usage
What is cellular pathology and what are its 2 main subdivisions?
Cellular pathology is the examination of organs, tissues and cells for diagnosis and to guide treatment, often cancer work.
Also conduct autopsies.
The 2 main subdivisions are
1. Histopathology - examines diseased tissues
2. Cytopathology - examines diseased individual CELLS, not tissues
What is the difference between histopathology and cytopathology?
Histopathology investigates and diagnoses disease from the examination of TISSUES, whereas cytopathology investigates and diagnoses from the examination of ISOLATED CELLS
What is the importance of a microscopic diagnosis?
Actually know whats going on! Ie. gives a definitive diagnosis.
It can be essential before major surgery to remove a lesion, as it wil lguide the type and extent of intervention.
Give 4 examples of histology specimen
- Core biopsies
- Cancer resection specimens
- Excised skin lesions
- Endoscopic biopsies
Give 4 examples of cytology specimen.
- Fine needle aspiration of breast, thyroid, salivary glands or lung
- Effusions
- Cervical smears
- Sputum
- Urine
What are the advantages of cytology?
- fast and cheap
- can look at cells in a fluid
- non-invasive, or minimally, so very safe
- used as a preliminary test
What are the disadvantages of cytology compared to histology?
- cytology has higher orror rates becasue it can’t see the architecture of the tissue, only individual cells.
What sort of question does cytoloy provide the answer to as opposed to histology?
- Cytology ansers questions such as “is it cancer or not?”, so it is used to CONFIRM/EXCLUDE cancer/dysplasia; not to diagnose any other condition with accuracy
- Histology provides answers to questions such as “What kind of inflammatory condition is it?”
What sort of information does histology provide?
- information on tissue architecture
- information of completeness of excision
- ## information on grading and staging
Peritoneal fluid analysis falls into which subdivision of cellualar pathology?
- cytology (individual cells that can be found in fluids)
Which organs could be affected by serous carcinoma and causing abdominal distension in a 63 year old female presenting with bilateral pelvic adnexal masses and ascites?
- Ovary
- Fallopian tubes
- Uterus
- Cervix
- Peritoneum
What does neoplastic mean?
- tissue that shows abnormal growth (often forms a mass)
What is the difference between a primary tumour and a metastasis?
A primary tumour is when the abnormality is at its origin still, whereas a emtastasis is when the abnormality has moved,, it comes from somewhere else
What does coeliac disease look like in histology?
The villi have thikened and flattened and there are a lot more cells within the lamina propria.
What can histopathologists tell us?
- Type of cancer
- Grade of cancer
- Stage of cancer
- Completeness of excision and if margins are involved which ones
- Likely efficacy or further treatments
What is adenoma?
It is a type of cancer that forms in mucus-secreting glands throughout the body.
Eg. Lung, prostate, pancreatic, oesophageal, colorectal (doesn’t mean that lung cancer is necessarily adenoma, just that it can be!)
What is lymphoma?
Lymphoma is a type of cancer affecting the lymphatic system. There are 2 main types,
- Hodgkin lymphoma
- Non-hodgkin lymphoma
What is Hodgkin lymphoma?
It is a type of lymphoma (cancer of lymphatic system). Lymphocytes are the cells that become abnormal.
- caracterised by presence of giant neoplastic cells called REED STERNBERG cells
- spreads slowly to sdjacent lymph nodes, but rarely metastasizes to distsnt site
- responsive to chemotherapy and radiation therapy
What is non-Hodgkin lymphoma?
It is a type of lymphoma (cancer affecting lymphatic system).
Do not contain Reed-Sternberg cells.
What is Mohs surgery?
It is performed by excising layer of diseased tissue, and then asking histopathologist if they have taken enough away. If pathologist sees diseased cell close to margin, then will suggest taking some more away.
= progressive removal till only cancer-free tissue remains.
What are ER and Her2 receptors and why are they relevant to histopathologists?
ER = estrogen receptor
- if breast cancer is positive to ER receptors (70%), then it will respond well to hormonal therapies
Her2 = human epidermal growth factor 2
- if breast cancer is Her2 positive, then Trastuzumab (Herceptin) is an effective ttt for this type of breast cancer.
=> so by testing for these receptors, the pathologist can orientate the treatment!
Tissue autolysis is a problem for pathologists preparing their specimen. What is autolysis, and what is the answer to this problem?
Autolysis is self-digeston of the cell which begins when the blood supply is cut off.
It destroys cells and tissue architecture, both of which we need for diagnosis!
We can block the biochemical process of autolysis with FIXATIVES.
1. Fixatives inactivate tissue enzymes and denature proteins
2. prevent bacterial growth
3. Harden tissue
What are fixatives and what are their 3 main functions?
Fixatives are the solution to stop cell autolysis before we observe it under the microscope.
Fixatives:
1. Prevent bacterial growth
2. Harden tissue - important for the cutting stage
3. Inactivate tissue enzymes and denature proteins
What is the fixation agent most comonly used?
Formalin
How do we get tissue hard enough to cut and observe?
- Need to dehydrate the tissue using alcohol
- Replace alcohol with xylene which mixes with wax
- Replace xylene with molten paraffin wax, which will even be inside the cells.
What is the machine that cuts the very thin slices for microscopy observation called?
a Microtome
What does haematoxylin stain and what colour?
haematoxylin stains nuclei purple
What does eosin stain and what colour?
Eosin staisn cytoplasm and connective tissue pink.
What is immunohistochemistry?
- is an additinal test to viewing of routinely stained slides
- demonstrates the presence in or on cells of specific substances, usually proteins by LABELLING THEM WITH ANTIBODIES.
- usually the anitbodies are noined to an enzyme that catalyses a colour-producing reaction
- most often substances are demonstrated by a brown colour.
What are cytokeratins and why are they useful in immunohistochemistry?
Cytokeratins are fibrous proteins exclusively found in almost all epithelia. Their presence demonstrates epithelial differentiation and the different cytokeratins (20 diff sorts) show tissue-specific distribution.
=> they can therefore be used to give information about the primary site of a carcinoma.
What does immunohistochemistry result CK7+/CK20- indicate?
CK7 positive, so primary site of carcinoma could be lung, breast, endometrium, ovary, thyroid
What does immunohistochemistry result CK7-/CK20+ indicate?
It indicates that the primary site of carcinoma could be large bowel, some gastric carcinomas
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.
In situ molecular tests show how DNA is altered in tissues prepared for microscopy:
Eg. FISH, to test gains of additional copies of Her2 gene in breast cancer.
What are frozen sections?
- urgent histopathology
- method of hardening tissue quickly
- less good that paraffin sections
- intra-operative! performed during surgery
- takes about 10 minutes from receiving specimen in lab to result
- the aim is to establish presence and nature of a lesion and influence the course of the operation
- accuracy not very good, about 96%
How does cell soze change with apoptosis?
Cell shrinks
How does cell size change with necrosis (oncosis)
Swelling
Does necrosis (oncosis) trigger inflammatory response?
yes