Sample collection & Tissue preparation

Question 1

List the main activities of cellular pathology?

Answer 1

Sample collection -> preservation -> processing -> analysis -> reporting

Question 2

What is biopsy?

Answer 2

Removal and examination of cells or tissue from a living body to diagnose disease.

Question 3

What factors influence choice of sampling method?

Answer 3

Tissue accessibility, invasiveness, diagnostic yield, and patient safety

Question 4

What is exfoliative cytology?

Answer 4

Collection of cells scraped or brushed from tissue surfaces

Question 5

Give two advantage of exfoliative cytology?

Answer 5

Minimally invasive; low cost; minimal discomfort; low complication risk

Question 6

Give two examples of exfoliative cytology use?

Answer 6

1. Cervical screening
2. Skin cell scrapes

Question 7

What is a punch biopsy used for?

Answer 7

Diagnosing skin diseases and skin cancers

Question 8

What does a punch biopsy remove?

Answer 8

A full-thickness cylindrical disc of skin

Question 9

Why is punch biopsy size important?

Answer 9

Small biopsies may be difficult to process and interpret histologically.

Question 10

What is endoscopy?

Answer 10

Visual examination of internal organs using a flexible tube with a camera and sampling tools

Question 11

Name 4 types of endoscopy?

Answer 11

1. Gastroscopy
2. Bronchoscopy
3. Sigmoidoscopy
4. Colonoscopy

Question 12

What is Fine Needle Aspiration (FNA)?

Answer 12

A minimally invasive technique using a thin needle to collect cells or tissue fragments in fluid.

Question 13

Major limitation of FNA?

Answer 13

Lack of tissue architecture

Question 14

What is a core needle biopsy?

Answer 14

Use of a larger needle to remove a core (cylinder) of tissue.

Question 15

Key advantage of core biopsy over FNA?

Answer 15

Preserves tissue architecture -> higher diagnostic accuracy

Question 16

Difference between incisional and excisional biopsy?

Answer 16

Incisional removes part of a lesion; excisional removes the entire lesion with margins

Question 17

What is surgical resection?

Answer 17

Removal of part or all of an organ, often for cancer treatment and diagnosis

Question 18

Why must tissue samples be preserved immediately?

Answer 18

To prevent autolysis and putrefaction and preserve morphology

Question 19

Define fixation?

Answer 19

Chemical preservation of tissue to stabilise cellular structures and prevent degradation.

Question 20

What happens if tissue is poorly fixed?

Answer 20

Loss of morphology and compromised diagnostic accuracy

Question 21

What is the most common routine fixative in histology?

Answer 21

10% formalin

Question 22

What is formalin chemically?

Answer 22

An aqueous solution of formaldehyde

Question 23

What is the mechanism of formalin fixation?

Answer 23

Protein cross-linking

Question 24

Why is osmolarity important during fixation?

Answer 24

Prevents cell swelling or shrinkage that distorts tissue morphology

Question 25

List factors affecting fixation quality?

Answer 25

Tissue size, fixative concentration, time, temp, osmolarity

Question 26

Why is fixation considered a compromise?

Answer 26

No fixative perfectly preserves morphology while maintaining all molecular targets

Question 27

Why must tissue be processed before embedding?

Answer 27

Tissue contains water, which is incompatible with wax

Question 28

What are the 3 main stages of tissue processing?

Answer 28

Dehydration-> clearing-> wax infiltration

Question 29

What is dehydration and how is it performed?

Answer 29

Gradual removal of water using increasing concentrations of alcohol

Question 30

Why is dehydration gradual?

Answer 30

To prevent tissue distortion and osmotic

Question 31

What is clearing in tissue processing?

Answer 31

Replacement of alcohol with a solvent (e.g. xylene) compatible with wax

Question 32

Role of xylene in tissue processing?

Answer 32

Acts as an intermediary between alcohol and wax

Question 33

What is wax infiltration?

Answer 33

Replacement of clearing agent with molten wax to stabilise tissue

Question 34

Why is tissue processing usually automated?

Answer 34

Ensures consistency, reproducibility, and controlled reagent exposure

Question 35

What is embedding?

Answer 35

Orienting tissue in molten wax to form a solid block for sectioning

Question 36

Why is correct tissue orientation important?

Answer 36

Ensures accurate representation of tissue layers and margins

Question 37

What is microtomy?

Answer 37

Cutting thin tissue sections from wax blocks for microscopy

Question 38

Why must sections be thin?

Answer 38

To allow light penetration and effective staining

Question 39

What is H&E staining used for?

Answer 39

Routine assessment of tissue morphology

Question 40

What is immunohistochemistry (IHC)?

Answer 40

Detection of specific proteins using antibodies to aid diagnosis

Question 41

Outline the full histopathology workflow from patient to diagnosis?

Answer 41

Sample collection -> preservation -> reception -> grossing -> processing -> embedding -> microtomy -> staining -> microscopy -> reporting

Question 42

Why is fixation critical for diagnostic accuracy?

Answer 42

It preserves tissue morphology and antigen integrity, enabling reliable histological and immunohistochemical analysis

Question 43

Compare FNA and core needle biopsy?

Answer 43

FNA is minimally invasive but lacks architecture; core biopsy preserves tissue structure and provides higher diagnostic accuracy.

Question 44

How does histopathology contribute to cancer diagnosis and management?

Answer 44

It enables tumour classification, margin assessment, prognostic evaluation, and treatment planning