Intro To Pathological Processes

Question 1

Define disease

Answer 1

Pathological condition of a body part, organ or system characterised by an identifiable group of signs or symptoms

Question 2

What are the different pathology disciplines?

Answer 2

Chemical pathology
Haematology
Immunology
Medical microbiology
Cellular pathology

Question 3

What are the differences between histology and cytology?

Answer 3

Histology:
- often therapeutic as well as diagnostic
- can assess architecture as well as cellular atypia
- can differentiate invasive from in situ disease
- can provide information on completeness of excision and more complete information on grading and staging
- better for immunohistochemical and modular testing

Cytology:
- faster and cheaper
- non-invasive, minimally invasive and safe
- can be used for cells in fluids
- sometimes a preliminary test before other investigations or more tissue taken for histology
- higher inadequate and error rates
- generally used to confirm/exclude cancer/dysplasia and not to diagnose any other condition with accuracy

Question 4

Describe the process of fixation

Answer 4

Hold tissue in ‘suspended animation’
Usually use formalin - penetrates tissue at approximately 1mm/hr
Usually fix for 24-48 hrs
Large specimens should be sliced into for fixation
Tissue should ideally be placed in 10x it’s volume of fixative
Normally stained with H&E