13. Pathology Flashcards
what is the definition of pathology?
- the medical science concerned with all aspects of disease including the essential nature, causes, development as well as the structural and functional changes that result from the disease process
- the anatomical or functional manifestation of a disease
what are some specialities under pathology?
- toxicology
- immunology
- chemical pathology
- forensic medicine
- microbiology
- veterinary pathology
why is there lots of sub-specialisation in pathology?
due to the amount we now know about disease
what are signs and symptoms?
Signs = things that you can measure linked to disease like blood pressure
Symptoms = what the patient is feeling that leads them to seek healthcare
how can you make a diagnosis?
- usually what you see and what you can measure is enough
- Sometimes more invasive examination is needed to confirm diagnosis or rule out more serious things
Including: blood tests, imaging, core biopsy, bone marrow biopsy
what is an excisional biopsy?
removing the whole lesion in the process of diagnosis
what is an incisional biopsy?
small sample for diagnosis
checking for margins
what is a punch biopsy?
taking just a bit of the tissue from inside the lesion
what is a shaving biopsy?
taking a cutting from the surface of the lesion especially if it is on the skin
what is an endoscopic biopsy?
A small internal biopsy that samples atypical regions of organ surfaces.
They can also be used to do general mapping of the area
What is a resection specimen?
A whole tissue or organ sample removed during surgery
when do resection specimens not go through full lab testing?
if previous tests have determined it is benign
how are resection specimens analysed in a pathology lab?
- not always a full analysis, microscopy could just be enough to make a diagnosis
- stitches and dyes are used to help orientate the tissue to match with the body used to inform surgeons about what still needs to be removed and resection margins and inform targeted therapy
- get information about the patient from the specimen
what questions can histopathology answer?
- what is it?
- where is it from?
- what is it effecting?
- are the margins good?
- what treatments are best suited?
what are the steps of a histopathology sample?
- cut-up the surgical specimen
- embedding in paraffin (most samples arrive partially embedded)
- Sectioning
- histology slide making = slicing and staining
- diagnosis using a microscope
what is a hysterectomy?
a resection of the uterus, fallopian tubes and ovaries
what are fibroids?
tumours made of smooth muscle
when are fibroids benign?
if they are multiple and small
when are fibroids usually malignant?
if it is one large mass then it could be a sarcoma
what is the uterus wall made of?
smooth muscle
Histology of a benign fibroid
- Mostly pink
- spindle cells with bland nuclei
- mitosis not really occurring or easy to identify
- no necrosis or haemorrhage
Histology of a malignant fibroid?
- all the cells look different
- atypical nuclei
- haemorrhage
- lots of mitosis
how is breast cancer spread determined in surgery?
- look at the central lymph node
- drains the tumour
- if the cancer is in the lymph node then it needs to be removed
- removal of lymph nodes comes with comorbidites
- if the tumour reaches the skin then the staging increases
Histology of invasive breast carcinoma
- medium sized cells
- atypical nucleus
- need to test for specific markers like oestrogen and progesterone to give treatment recommendations
- use immunohistochemistry to test for receptors
- triple negative is biologically more effective but less responsive to treatment
histology of a soft tissue sarcoma
- very small dot like cells = myxoid
- some cells with a vacuole
- vacuole indicates making fat with means it is a liposarcoma
- due to the tumour type radiotherapy works really well to kill the tissue and turn it into scar tissue and solid lump rather then a soft tumour liable to burst
- still need surgery but a lot easier to remove
what is the purpose of fresh and frozen samples taken from surgery?
- real time analysis
- look for resection margins
- check you have the whole tumour with no damage to blood vessels or nerves
- much simple then with fixed samples as it can be ready in 30 mins opposed to a few days
why can you not give a definitive diagnosis off a frozen sample?
- frozen cells have gone through massive trauma so they lose details and structures unless they are very obvious
- need to ensure you have enough tissue to do extra analysis
- Verify diagnosis after fixing samples and reanalyse to give diagnosis a few days later
what needs to be remembered about frozen samples?
if the patient was contagious then the tissue could pose an infection risk
what stains are mainly used in pathology?
H&E stains or other dyes that are cheap and easy to use
NOTE there are other specialist dyes
What can immunohistochemistry tell us?
- what antigens are expressed by the tissue
- Presence of viruses
- helpful for diagnosis and prognosis
what is FISH used for?
- genetic testing
- Normally to identify translocations
what has surpassed FISH?
Next generation sequencing
what are the limits of histopathology examination?
- taking non-diagnostic or wrong bits of the tissue like necrotic tissue or capsules
- too little tissue to be able to examine it properly
- the tissue is very brittle and can fall apart
- the morphology is extremely hard to interpret
- histological diagnosis needs to be correlated with the other clinical findings and imaging
- complex cases involve the input of lots of healthcare professionals
what is a relatively new tumour phenotype and what does it mean?
- translocation of TRK
- expresses CD34 and S100
- it has unknown malignant potential
- tumours described by mutation are hard to diagnose by pathology as you cannot see a mutation
how can pathology contribute to the increase in medical knowledge?
- new entities and help correlate disease with behaviour
- could help link therapies with tumours and targets
- use what you know about tumours and look at the similarities between it and the new/rare tumour to inform treatment
