Gross pathology and the basis of disease

Question 1

What criteria should be used to describe lesions?

Answer 1

location
number/extent
demarcation
distribution
colour
size
shape
consistency and texture

Question 2

Describe this lesion

Answer 2

On the 1.forelimb, there was a clipped area measuring 10 x 5 cm. Within the clipped area is 2. a 3.well-demarcated, 4. focal, 5. pink to dark red, 6. 3 cm in diameter x 2 cm height 7. round, raised, 8. firm, hairless mass.

Question 3

Describe this lesion

Answer 3

The 1. stomach was 4. diffusely distended, 8. gas-filled and 5. diffusely dark red.

Question 4

Describe this lesion

Answer 4

Affecting 20% of the right kidney, within the renal cortex and extending into the medulla, was a focal, well-demarcated, 3 x 2 cm, light tan to dark red, wedge-shaped lesion.

Question 5

Describe this lesion

Answer 5

Affecting 30% of the tongue, on the left underside and extending to the lingual surface, there was a focal, moderately well demarcated, pink to red, 5 x 2 x 1 cm, oval, multinodular, firm mass

Question 6

Describe this lesion

Answer 6

Focally extensively, effacing the perineum and base of the tail, was a well-demarcated, black to red, approximately 1 meter by 50 cm x 10 cm, ulcerated, multinodular mass.

Question 7

Describe this lesion

Answer 7

Adhered to the viscera and mesentery of the ileum and paired caeca, were numerous, well demarcated, multifocal, up to 2 cm in diameter, pink to tan, round firm masses.

Question 8

Describe this lesion

Answer 8

Affecting up to 90% of the mammary gland, there was multifocal to coalescing, poorly demarcated areas of grey to light pink, friable tissue, admixed with haemorrhage and abundant light pink purulent exudate (pus).

Question 9

What are possible causes of cell injury?

Answer 9

Oxygen deprivation
Physical agents
Chemical agents and drugs
Infectious agents
Immunologic reactions
Genetic derangements
Nutritional imbalances

Question 10

What are the possible reasons for oxygen deprivation (hypoxia) causing cell injury?

Answer 10

Reduced blood flow (= ischaemia)
Inadequate oxygenation of the blood (cardiorespiratory failure)
Decreased oxygen-carrying capacity of the blood (anaemia, carbon monoxide poisoning, blood loss)

Question 11

Give examples of physical agents that can cause cell injury

Answer 11

mechanical trauma
extreme temps
radiation
electric shock

Question 12

Give examples of chemical agents and drugs that can cause cell injury

Answer 12

Hypertonic concentrations
Poisons
Environmental pollutants
Insecticides, herbicides
therapeutic drugs

Question 13

Give examples of infectious agents that can cause call injury

Answer 13

viruses (& prions)
Bacteria
Fungi
Parasites (protozoa, helminths)

Question 14

What is reversible degeneration?

Answer 14

Early response to cell injury
Depletion of cellular energy stores (ATP):
- cellular swelling/fatty change
- alteration of intracellular organelles
- affects functionality of cell

Question 15

Why do cells swell after injury?

Answer 15

Question 16

What causes fatty change in an injured cell?

Answer 16

Question 17

Describe the features of necrosis after cell injury

Answer 17

• Always pathologic
• Cell membranes are damaged
• Often with inflammation (neutrophils attack the leaked cell contents)

Question 18

Describe the features of apoptosis after cell injury

Answer 18

• may be physiologic or pathologic
• Cell membranes are intact
• No inflammation
• ‘Cell suicide’ or ‘programmed death’
• Cell shrinks

Question 19

Describe the cytoplasmic changes that occur in necrosis?

Answer 19

Hypereosinophilia
Cytoplasmic vacuolation

Question 20

Describe the nuclear changes seen in necrosis

Answer 20

Question 21

Label the histological signs of necrosis

Answer 21

Question 22

Give examples of the patterns of tissue necrosis

Answer 22

Coagulative necrosis
Liquefactive necrosis
Gangrenous necrosis
Caseous necrosis
Fat necrosis

Question 23

Describe coagulative necrosis

Answer 23

Localized area of coagulative necrosis caused by ischaemia due to vascular obstruction

Question 24

Describe liquefactive necrosis

Answer 24

Collection of necrotic neutrophils and tissue debris

Question 25

describe gangrenous necrosis

Answer 25

Variant of coagulative necrosis Usually applied to a limb that has lost its blood supply(also tail, ears, udder) 3 types of gangrene: dry, moist or gas

Question 26

Describe caseous necrosis

Answer 26

Conversion of dead cells into a friable mass (resembles cheese) More chronic than coagulation necrosis

Question 27

Describe fat necrosis

Answer 27

Focal areas of fat destruction Fat appears while, firm, chalky, resembling flecks of soap Caused by release of pancreatic lipases

Question 28

What are the microscopic morphological alterations seen in apoptosis?

Answer 28

Cell shrinkage Chromatin condensation Cytoplasmic blebs and apoptotic bodies Phagocytosis of apoptotic cells or cell bodies

Question 29

What are the types of cell/tissue adaptation and what causes them?

Answer 29

Question 30

Describe the ability of labile cells to adapt

Answer 30

Routinely proliferate: → epidermis, intestinal epithelium, bone marrow cells - hyperplasia more likely

Question 31

Describe the ability of stable cells to adapt

Answer 31

Intermediate in ability to regenerate/divide → bone, cartilage, smooth muscle - hypertrophy more likely

Question 32

Describe the ability of permanent cells to adapt

Answer 32

Very little capacity to regenerate → neurons, cardiac/skeletal muscle cells - can undergo hypertrophy

Question 33

What is the stimulus of hypertrophy and hyperplasia?

Answer 33

Increased functional demand (e.g. muscle) stimulation by hormones (e.g. uterus during pregnancy) growth factors (or even some viruses)

Question 34

Give an example of physiologic atrophy

Answer 34

e.g. during embryonal/fetal development, uterus atrophy after parturition

Question 35

What are the possible causes of pathologic atrophy?

Answer 35

Decreased workload (atrophy of disuse) Loss of innervation (denervation atrophy) Diminished blood supply Inadequate nutrition Loss of endocrine stimulation Pressure

Question 36

What are the possible causes of metaplasia?

Answer 36

Chronic irritation Deficiencies e.g. Vit A Result of cell/tissue injury Oestrogen toxicity

Question 37

What is metaplasia?

Answer 37

Potentially reversible change in which one differentiated cell type (epithelial or mesenchymal) is replaced by another cell type

Question 38

What is the most common metaplasia?

Answer 38

columnar to squamous epithelial

Question 39

Define agenesis

Answer 39

never developed

Question 40

Define aplasia

Answer 40

started development but stopped early

Question 41

Define atresia

Answer 41

absence of an orifice

Question 42

Define hypoplasia

Answer 42

incomplete development

Question 43

Define dysplasia

Answer 43

disordered growth