What are the three hepatic zones?
Periportal (centroacinar) - around portal triads Midzonal Centrilobular (periacinar) - borders hepatic venules
What is the 'limiting plate'?
This is the boundary between the portal tract and surrounding liver parenchyma.
How does the prognosis of portosystemic shunts that are congenital and acquired differ?
Congenital - usually one shunt so more easily surgically corrected Acquired - shunts are secondary to fibrosis and are multiple so harder to correct.
What might indicate the prescence of a portosystemic shunt on microscopy?
The lack of a portal vein prescence
What developmental/congenital disorders can affect the liver?
Congenital cysts Displacements (e.g. diaphragmatic hernia) Tension lipidosis (focal areas of subscapular fatty change) Capsular fibrosis Telangiectasis (focal areas of dilated tissue)
Describe when venous congestion of the liver might occur, the gross and microscopic appearance of an affected liver.
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
What are the common pigments that may be seen microscopically? Are they significant?
Melanin - incidental Haemosiderin - blood breakdown product but often incidental Bile - jaundice Lipofuscin (brown pigment) - incidental with ageing.
What can cause hydropic change? Is it reversible?
Hypoxia, mild toxin damage, metabolic stress It is reversible
In what disease goes glycogen accumulation occur?
What is the gross & micro apearance of a liver undergoing vacuolar hepatopathy?
Gross - Enlarged pale liver Micro - multifocal/diffuse swelling/vacuolation of hepatocytes
What things can cause lipidosis of the liver?
Diet (obesity and starvation) Increased energy demand (pregnancy, lactation) Disease (diabetes mellitus, ketosis, pregnancy toxaemia)
Why does lipidosis occur?
Hepatocytes malfunction and cant combine fatty acids with proteins to form LDL.
What does the following image depict? How does this disease occur?
Lysosomal storage disease. This is an inherited deficiency in lysosomal enzymes leading to storage of material inside macrophages that accumulate at multiple sites.
What does the gross appearance of an amyloidotic liver look like?
Liver enlarged and friable with a texture like candle wax.
How can necrosis of the liver occur?
What are the different patterns of liver necrosis and what are they associated with?
Random - infectious
Zonal - Ischaemia/toxic
Massive - hepatosis dietetica
Describe the different patterns of fibrosis of the liver.
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
What are the different types of inflammation of the liver?
Hepatitis - liver parenchyma
Cholangitis - bile ducts
Cholangiohepitits - both
Describe what happens in acute hepatits, and the events that can happen if the animal survives.
Necrosis followed by inflammation. If survives then the following can happen:
- Resolution by regeneration
- Fibrosis and Scarring
- Encapsulation and abscessation
- Persistance of granulomatous disease
What types of virus can cause hepetitis?
Adenoviruses (canine infectous hepetitis)
Why is canine infectious hepetitis so infective?
It is shed in the urine long term
Describe the lesions seen in neonates infected with herpes virus.
Multinodular white dots
Foci of necrosis with nuclear inclusion bodies
Necrosis can also occur in lungs, spleen, kidneys and adrenals
What are the two forms of FIP?
Wet and Dry forms
What routes of infection are there for bacterial hepatitis?
Direct extension from adjacent tissues
Haematogenous spread e.g. umbilical vein, portal vein from alimentary tract, hepatic artery
Abcessation - umbilical infecitons, rumenitis
What pathology is associated with Fusobacterium necrophorum?
Multiple pale foci throughout the liver which may form abscesses.
Micro: Coagulative necrosis with peripheral bacteria
What is the aetiology of 'black disease'?
Clostridium novyi type B infection which often precipitates from fluke migration through the liver.
Decribe gross and microscopic lesions associated with 'black disease'
Subcut venous congestion
Fibrinous third space fluid
Pale foci of necrosis containing bacteria surrounded by a ring of haemmorrhage
Describe pathology findings of Clostridium haemolyticum
Large necrotic focus in the liver with haemoglobin staining of kidneys
What animals does Tyzzers disease infect? What is the causative organism?
Laboratory rodents, yound horses, immunosupressed cats/dogs.
What stain is used in the following image and what organism does it visualise?
Clostridium piliforme. Silver stain. 'Wheat Sheaf' appearance
What does this image depict?
A leptospire. This is heamosiderin staining due to the haemolytic aneamia caused by the organism. There is also hepatocyte dissociation causing cholestasis.
Describe the pathological changes associated with Salmonellosis.
Severe haemorrhagic inflammation of the ileum.
paratyphoid nodules in the liver - pale foci of necrosis
Foci of necrosis
Mononuclear inflammatory cells
Are parasites in the liver pathologic?
Most are indicental apart from fluke.
What does the following image show?
Incidental fibrous tags formed following repair after parasites have left the liver.
Describe acute and chronic liver intoxication.
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.
What is cholecystitis? And what is a common reaction to this?
Inflammation of the gall bladder. Hyperplasia of the mucosa is common reaction to irritation of this area.
How can biliary obstruction occur and what is the severity of a rupture?
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.
What does the following image depict?
a malignant neoplasia of the liver
What microsopy findings indicate acute pancreatitis?
Haemorrhagic oedema and necrosis affecting pancreas and peripancreatic fat.
Is nodular hyperplasia significant?
What types of pancreatic neoplasia are rare/not rare?
Adenoma - rare
Carcinoma more common and often very agressive.