Introduction

Question 1

What is pathology?

Answer 1

Study of disease and cellular dysfunction
Diagnosis
Behind the scenes

Question 2

What is disease?

Answer 2

Pathological condition characterised by identifiable signs/symptoms
Failed homeostasis
Whole person/organ/tissue
Cell central player

Question 3

Pathology disciplines

Answer 3

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)

Question 4

Other pathology

Answer 4

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

Question 5

Importance of microscope

Answer 5

Definitive diagnosis

Diagnosis before major surgery - guide the extent of surgery necessary

Question 6

Histology Vs cytology

Answer 6

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

Question 7

Things to ask when analysing histology/cytology sample

Answer 7

Pattern
Normal?
Inflammatory?
benign/malignant?
Primary or metastasis?

Question 8

What can we assess from histology?

Answer 8

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

Question 9

What does a poorly differentiate carcinoma mean?

Answer 9

No resemblance of previous cell types

More aggressive disease

Question 10

Stage of cancer graded with

Answer 10

TNM
Tumour, nodes, metastases
Determine next steps eg: chemo, surgery, discharge

Question 11

Pathology process from patient to report

Answer 11

Fixative (formalin) —> trimming (cassette) —> dehydration (alcohol) —> embedding (paraffin wax) —> blocking —> Microtomy —> staining (H&E) —> mounting (mounting medium & coverslip)

Question 12

Immunohistochemistry

Answer 12

Shows presence of antigens using labelled antibodies
Antibody joined to enzyme (peroxidase)
Catalyse colour producing reaction (brown)

Question 13

What can be detected with immunohistochemistry?

Answer 13

Anything that has antigens:

• smooth muscle cells
• Cadherins (cell adhesion molecules)
• Growth factor receptor (HER2)
• Hormone receptor (ER)
• Microorganisms

Question 14

Cytokeratins in immunohistochemistry

Answer 14

Intracellular fibrous proteins
Present in all epithelia
Certain cytokeratins combinations in certain tissues = tissue specific
Give info about the primary site of carcinoma

Question 15

Molecular pathology

Answer 15

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

Question 16

Frozen sections use and negative

Answer 16

Urgent
Used during operation
10-15 mins
Influence the course of operation
- misinterpreted sometimes
- absence of diagnostic tissue in frozen section

Question 17

Frozen section steps

Answer 17

Fresh specimen
Cut 
Freeze
Microtomy in cryostat 
Wet specimens discarded after 1 month
Slides and paraffin blocks kept forever - further tests/review

Question 18

What is included in histology report

Answer 18

Clinical details - age/gender/medical history/symptoms/smoker?/clinical thoughts
Macroscopic - sample size
Microscopic - description, diagnosis (specific features)
Conclusion (specimen and diagnosis)
Reported by: NAME