Pathology of the Liver and Pancreas

Question 1

What are the three hepatic zones?

Answer 1

Periportal (centroacinar) - around portal triads Midzonal Centrilobular (periacinar) - borders hepatic venules

Question 2

What is the ‘limiting plate’?

Answer 2

This is the boundary between the portal tract and surrounding liver parenchyma.

Question 3

How does the prognosis of portosystemic shunts that are congenital and acquired differ?

Answer 3

Congenital - usually one shunt so more easily surgically corrected Acquired - shunts are secondary to fibrosis and are multiple so harder to correct.

Question 4

What might indicate the prescence of a portosystemic shunt on microscopy?

Answer 4

The lack of a portal vein prescence

Question 5

What developmental/congenital disorders can affect the liver?

Answer 5

Congenital cysts Displacements (e.g. diaphragmatic hernia) Tension lipidosis (focal areas of subscapular fatty change) Capsular fibrosis Telangiectasis (focal areas of dilated tissue)

Question 6

Describe when venous congestion of the liver might occur, the gross and microscopic appearance of an affected liver.

Answer 6

Secondary to heart failure Gross : enlarged and oozes blood from cut surface. ‘Nutmeg liver’ Micro: Engorged sinusoids, Congested periacinar areas with atrophied hepatocytes, fatty change of periportal areas

Question 7

What are the common pigments that may be seen microscopically? Are they significant?

Answer 7

Melanin - incidental Haemosiderin - blood breakdown product but often incidental Bile - jaundice Lipofuscin (brown pigment) - incidental with ageing.

Question 8

What can cause hydropic change? Is it reversible?

Answer 8

Hypoxia, mild toxin damage, metabolic stress It is reversible

Question 9

In what disease goes glycogen accumulation occur?

Answer 9

Hypoadrenocorticism

Question 10

What is the gross & micro apearance of a liver undergoing vacuolar hepatopathy?

Answer 10

Gross - Enlarged pale liver Micro - multifocal/diffuse swelling/vacuolation of hepatocytes

Question 11

What things can cause lipidosis of the liver?

Answer 11

Diet (obesity and starvation) Increased energy demand (pregnancy, lactation) Disease (diabetes mellitus, ketosis, pregnancy toxaemia)

Question 12

Why does lipidosis occur?

Answer 12

Hepatocytes malfunction and cant combine fatty acids with proteins to form LDL.

Question 13

What does the following image depict? How does this disease occur?

Answer 13

Lysosomal storage disease. This is an inherited deficiency in lysosomal enzymes leading to storage of material inside macrophages that accumulate at multiple sites.

Question 14

What does the gross appearance of an amyloidotic liver look like?

Answer 14

Liver enlarged and friable with a texture like candle wax.

Question 15

How can necrosis of the liver occur?

Answer 15

Toxins

Infections

Nutritional deficiencies

Ischaemia

Question 16

What are the different patterns of liver necrosis and what are they associated with?

Answer 16

Random - infectious

Zonal - Ischaemia/toxic

Massive - hepatosis dietetica

Question 17

Describe the different patterns of fibrosis of the liver.

Answer 17

Periacinar fibrosis - Surrounds CV

Biliary fibrosis - around bile ducts also inflammation centred on portal triads

Post-necrotic scaring - following massive necrosis

Cirrhosis - years of cycles of fibrosis followed by regeneration

Question 18

What are the different types of inflammation of the liver?

Answer 18

Hepatitis - liver parenchyma

Cholangitis - bile ducts

Cholangiohepitits - both

Question 19

Describe what happens in acute hepatits, and the events that can happen if the animal survives.

Answer 19

Necrosis followed by inflammation. If survives then the following can happen:

• Resolution by regeneration
• Fibrosis and Scarring
• Encapsulation and abscessation
• Persistance of granulomatous disease

Question 20

What types of virus can cause hepetitis?

Answer 20

Adenoviruses (canine infectous hepetitis)

Herpesviruses (EHV)

Coronaviruses (FIP)

Question 21

Why is canine infectious hepetitis so infective?

Answer 21

It is shed in the urine long term

Question 22

Describe the lesions seen in neonates infected with herpes virus.

Answer 22

Multinodular white dots

Foci of necrosis with nuclear inclusion bodies

Necrosis can also occur in lungs, spleen, kidneys and adrenals

Question 23

What are the two forms of FIP?

Answer 23

Wet and Dry forms

Question 24

What routes of infection are there for bacterial hepatitis?

Answer 24

Direct extension from adjacent tissues

Haematogenous spread e.g. umbilical vein, portal vein from alimentary tract, hepatic artery

Abcessation - umbilical infecitons, rumenitis

Question 25

What pathology is associated with Fusobacterium necrophorum?

Answer 25

Multiple pale foci throughout the liver which may form abscesses.

Micro: Coagulative necrosis with peripheral bacteria

Question 26

What is the aetiology of ‘black disease’?

Answer 26

Clostridium novyi type B infection which often precipitates from fluke migration through the liver.

Question 27

Decribe gross and microscopic lesions associated with ‘black disease’

Answer 27

Subcut venous congestion

Fibrinous third space fluid

Pale foci of necrosis containing bacteria surrounded by a ring of haemmorrhage

Question 28

Describe pathology findings of Clostridium haemolyticum

Answer 28

Large necrotic focus in the liver with haemoglobin staining of kidneys

Question 29

What animals does Tyzzers disease infect? What is the causative organism?

Answer 29

Laboratory rodents, yound horses, immunosupressed cats/dogs.

Clostridium piliforme

Question 30

What stain is used in the following image and what organism does it visualise?

Answer 30

Clostridium piliforme. Silver stain. ‘Wheat Sheaf’ appearance

Question 31

What does this image depict?

Answer 31

A leptospire. This is heamosiderin staining due to the haemolytic aneamia caused by the organism. There is also hepatocyte dissociation causing cholestasis.

Question 33

Describe the pathological changes associated with Salmonellosis.

Answer 33

Gross

Severe haemorrhagic inflammation of the ileum.

paratyphoid nodules in the liver - pale foci of necrosis

Micro:

Foci of necrosis

Mononuclear inflammatory cells

Question 34

Are parasites in the liver pathologic?

Answer 34

Most are indicental apart from fluke.

Question 35

What does the following image show?

Answer 35

Incidental fibrous tags formed following repair after parasites have left the liver.

Question 36

Describe acute and chronic liver intoxication.

Answer 36

Acute: widespread bodily haemorrhage as the liver consumes and fails to produce clotting factors.

Chronic: fibrosis and biliary hyperplasia. The liver continually is damaged and regenerates so chronic intoxication is often not noticed until it reaches a very late stage.

Question 37

What is cholecystitis? And what is a common reaction to this?

Answer 37

Inflammation of the gall bladder. Hyperplasia of the mucosa is common reaction to irritation of this area.

Question 38

How can biliary obstruction occur and what is the severity of a rupture?

Answer 38

Parasites, choleliths (rare). Obstruction from nearby inflammatory or neoplastic process.

Rupture is very severe as omentum can’t contain the leak and will lead to peritonitis.

Question 39

What does the following image depict?

Answer 39

a malignant neoplasia of the liver

Question 40

What microsopy findings indicate acute pancreatitis?

Answer 40

Haemorrhagic oedema and necrosis affecting pancreas and peripancreatic fat.

Question 41

Is nodular hyperplasia significant?

Answer 41

No

Question 42

What types of pancreatic neoplasia are rare/not rare?

Answer 42

Adenoma - rare

Carcinoma more common and often very agressive.