Introduction Flashcards
What is pathology?
Study of disease and cellular dysfunction
Diagnosis
Behind the scenes
What is disease?
Pathological condition characterised by identifiable signs/symptoms
Failed homeostasis
Whole person/organ/tissue
Cell central player
Pathology disciplines
Chemical - Biochemical investigation of disease (endocrinology, diabetes etc)
Haematology - blood diseases (clotting, leukaemia, transfusion)
Immunology - disease of immune system (allergy, autoimmunity)
Medical microbiology - disease causing microbes (antibiotic advice)
Cellular pathology - examine organs, tissues and cells for diagnosis (histopatholgy, cytopatholgy)
Other pathology
Cytopathology - Cells rather than tissue
Neuropathology - brain, spinal cord, nerves and muscle
Forensic pathology - suspicious/criminal deaths, detailed autopsies, expert court witnesses
Paediatric pathology - tissue samples from children, foetal/perinatal/paediatric autopsies
Importance of microscope
Definitive diagnosis
Diagnosis before major surgery - guide the extent of surgery necessary
Histology Vs cytology
Histology
- core biopsies, excisions, cancer resection (BIG)
- therapeutic and diagnostic
- assess architecture and cell
- differentiate between invasive and in situ
- info on completeness of excision
- grading and staging
- immunohistochemical and molecular testing
Cytology
- FNA (fine needle aspirates)
- faster and cheaper
- non invasve/minimally
- cells in fluids/preliminary test before histology
- error rates HIGHER
- usually to exclude or confirm cancer
Things to ask when analysing histology/cytology sample
Pattern Normal? Inflammatory? benign/malignant? Primary or metastasis?
What can we assess from histology?
Type of cancer Grade Completeness of excision - margins Stage of cancer Efficacy of certain drugs (does cancer display certain receptors eg HER2) Management of patient/further treatment
What does a poorly differentiate carcinoma mean?
No resemblance of previous cell types
More aggressive disease
Stage of cancer graded with
TNM
Tumour, nodes, metastases
Determine next steps eg: chemo, surgery, discharge
Pathology process from patient to report
Fixative (formalin) —> trimming (cassette) —> dehydration (alcohol) —> embedding (paraffin wax) —> blocking —> Microtomy —> staining (H&E) —> mounting (mounting medium & coverslip)
Immunohistochemistry
Shows presence of antigens using labelled antibodies
Antibody joined to enzyme (peroxidase)
Catalyse colour producing reaction (brown)
What can be detected with immunohistochemistry?
Anything that has antigens:
- smooth muscle cells
- Cadherins (cell adhesion molecules)
- Growth factor receptor (HER2)
- Hormone receptor (ER)
- Microorganisms
Cytokeratins in immunohistochemistry
Intracellular fibrous proteins
Present in all epithelia
Certain cytokeratins combinations in certain tissues = tissue specific
Give info about the primary site of carcinoma
Molecular pathology
How diseases are caused by alterations in DNA, RNA
Use in situ tests to show DNA alteration
Eg FISH - tests for gains of additional copies of Her2 gene
Or if certain mutations are present in gene
MRNA expression - level of activity of genes
MRNA signatures - how a tumour will behave
