1. Introduction

Question 1

What is a histology?

Answer 1

Core biopsies - used to find actual causes or what exactly something is.

Question 2

What is a cytology?

Answer 2

Fine needle aspirates eg of breast - used to see if it is cancer.

Question 3

What does the grade of cancer refer to?

Answer 3

How close are the cells to normal cells?

Question 4

What does the stage of cancer refer to?

Answer 4

Size/extent of tumour and whether or not has spread to other tissues

Question 5

How can histology help in cancer surgery other than just finding the type, grade and stage of cancer?

Answer 5

Completeness of excision and if margins are involved which.
Likely efficacy of further treatments eg HER2 a growth factor receptor which predicts the response of breast cancer to the drug Herceptin.

Question 6

How do you stop the process of autolysis (after a specimen has been taken)? What does it do?

Answer 6

Fixation - formalin.

Inactivated tissue enzymes, denatures proteins, prevents bacterial growth, hardens tissue.

Question 7

Once fixed what happens to a specimen?

Answer 7

Trimming - Samples taken, size of stamp, put into cassette and into formalin.

Question 8

How are specimens hardened?

Answer 8

Dehydrate using alcohol in vacuum, replace alcohol with xylene, replace xylene with molten paraffin wax.

Question 9

After hardening, how are slices of specimen taken?

Answer 9

Take tissue out of cassette and put onto metal block. Fill with molten paraffin wax, place body of cassette on top. Set, remove metal block, cut into thin sections using microtome.

Question 10

How are the slices of section put onto the microscope slide?

Answer 10

Float on water bath and picked up onto microscope slide

Question 11

What stain is typically used on sections? How does it work?

Answer 11

H&E
Haematoxylin - nuclei purple
Eosin - cytoplasm and connective tissue pink

Question 12

How is the tissue slice preserved and protected?

Answer 12

Mounting - mounting medium applied, and coverslip put on top

Question 13

What is immunohistochemistry?

Answer 13

Demonstrates substances in or on cells by labelling them with specific antibodies. Usually the antibody is joined to an enzyme that catalyses a colour producing reaction.

Question 14

What colour does immunohistochemistry usually highlight substances?

Answer 14

Brown

Question 15

What could be identified in immunohistochemistry to show smooth muscle cells?

Answer 15

Contractile protein actin

Question 16

What are cytokeratins?

Answer 16

Intracellular fibrous proteins present in almost all epithelia. Give information about primary site of a carcinoma.

Question 17

What is molecular pathology?

Answer 17

Studies how diseases are caused by alterations in normal cellular molecular biology - DNA, RNA, proteins

Question 18

Give an example of an in situ molecular test that shows how DNA is altered in tissues prepared for microscopy

Answer 18

FISH eg gains of additional copies of Her2 gene in breast cancer

Question 19

What type of sequencing allows may genes to be tested simultaneously for mutations?

Answer 19

Next generation sequencing

Question 20

What can mRNA expression profiling methods show?

Answer 20

How active a large number of genes are, at the RNA level - so can predict how a tumour is likely to behave

Question 21

When are frozen sections used? What is it?

Answer 21

Intra-operative, when result determines course of operation eg if is cancer for resection, is rapid freezing of tissue on a cryostat.

Question 22

What is the problem with frozen sections?

Answer 22

Morphology not as good, so reduced accuracy (misinterpretation leading to false negatives, and a sense of diagnostic tissue in frozen section).