Histo: Fundamentals of Histology

Question 1

Describe the appearane of neutrophils.

Answer 1

Multilobed nuclei with lots of granules

Question 2

In what states might you seen an abundance of lymphomcytes?

Answer 2

Chronic inflammation

Lymphoma

Question 3

Describe the appearance of eosinophils.

Answer 3

Bi-lobed nucleus with red granules

Question 4

List three conditions that could cause eosinophilia.

Answer 4

Allergic reactions

Parasitic infections

Malignancy (Hodgkin’s Lymphoma)

Question 5

Describe the appearance of the oesophagus in eosinophilc oesophagitis.

Answer 5

Horizontal striae are seen within the oesophagus (feline oesophagus)

Question 6

Describe the appearance of mast cells.

Answer 6

Large cells containing a lot of granules

Question 7

Describe the appearance of macrophages.

Answer 7

Large cells with lots of cytoplasm

Question 8

In what states do macrophages tend to appear?

Answer 8

Late acute inflammation (macrophages clear up the debris)

Chronic inflammation (become secretory rather than phagocytic)

Question 9

Define granuloma.

Answer 9

Organised collection of activated macrophages.

Question 10

Describe the appearance of macrophages in granulomas.

Answer 10

Epithelioid macrophages - they have a lot of cytoplasm making them look like epithelial cells

Question 11

What cytological feature is suggestive of a good sputum sample?

Answer 11

Pigmented macrophages - this suggests that they have come from the alveoli

Question 12

What do macrophages in granulomas fuse together to form?

Answer 12

Langerhans giant cells

Question 13

List some causes of granulomas.

Answer 13

• TB
• Leprosy
• Cat scratch fever
• Fungal infections
• Sarcoidosis

Question 14

List Types of Tumours

Answer 14

• Carcinomas (malignant tumours of EPITHELIAL cells)
• Sarcomas (malignant tumours of CONNECTIVE TISSUE - BONES, JOINTS, FAT, MUSCLE, CARTILAGE, BLOOD VESSELS)
• Lymphoma (malignant tumours of Lymphatic system )
• Melanoma (malignant tumours of melanin cells)
• NOTE: tumours are defined based on their presumed cell of origin

Question 15

List three types of carcinoma.

Answer 15

• Squamous cell carcinoma
• Adenocarcinoma
• Transitional cell carcinoma

Question 16

What are two key features of squamous cell carcinomas?

Answer 16

Keratin production (* NOTE: not all squamous epithelium produces keratin (e.g. oesophagus)

Intercellular bridges

Question 17

What are two key features of adenocarcinomas?

Answer 17

Mucin production

Glands

Question 18

Which stain is used for Melanin?

Answer 18

Fontana stain

Question 19

What is the difference between a histochemical stain and an immunhistochemical stain?

Answer 19

• Histochemical stain - based on the chemical reaction between the stain and the tissue. The product will have a specific colour or other property that can be identified
• Immunhistochemical - involves using antibodies to detect a specific antigen within the tumour

Question 20

What type of stain is haematoxylin and eosin?

Answer 20

Histochemical stain - one part will react with the acidic component of the tissue, the other part will react with the basic component

Question 21

What stain is used for iron?

Answer 21

Prussion blue

Question 22

Which stain is used for amyloid?

Answer 22

Congo red

When viewed under polarised light, it produces apple green birefringence

Question 23

Describe the mechanism of:

1. Immunofluorescence
2. Immunoperoxidase

Answer 23

1. Immunofluorescence
   
   • ​​An antibody will be raisd against a particular antigen
   • Another antibody will be raised against the Fc component of the previous antibody, this antibody will be attached to a fluorescence marker
   • The first antibody will be to a specific antigen on the tissue and then the second antibody will bind to the first antibody - the flueorscence can then be detected
2. Immunoperoxidase
   
   • ​​An antibody is added to the tissue which binds to a particular antigen
   • An enzyme is then added which binds to the antibody
   • A substrate is then added which produces a product of a certain colour

Question 24

What is a key immunological lymphoid marker?

Answer 24

CD45

Question 25

What is a classic histological feature of HSV infection?

Answer 25

Cells with multiple nuclei

Question 26

What is the most common histochemical stain used to visualise cells for light microscopy, such as that used for diagnosis of cancers?

Answer 26

Haematoxylin and eosin stain

Question 27

What stain is used to visualise amyloid on histological specimens?

Answer 27

Congo Red