Liver and Pancreas Pathology Flashcards
What is contained within the portal areas?
- Portal vein [nutrients from SI]
- Hepatic artery [oxygen]
- Bile ducts
Where do the radiating hepatocytes converge?
Central vein
What are the 3 hepatic zones?
- Periportal (centroacinar): around portal triads
- Midzonal
- Centrilobular (periacinar: bordering hepatic venules
What is the main congenital/developmental disorder of the liver? What other form exists?
Portosystemic shunt
- Congenital: shunting blood to vena cava, azygous or renal vein, usually single communication between vessels, easily surgically treatable
- Acquired: shunts 2* to fibrosis of the liver in older animals, multiple thin walled shunts -> more difficult to treat
What is the limiting plate?
Area around portal triad - used to decide whether inflammation is contained within portal tract or has spread to hepatocytes
How may portosystemic shunt be diagnosed microscopically?
Biopsy -> microscope -> If portal vein is missing then shunt is present
Give 5 other congenital/developmental disorders of the liver
- Congenital cysts (mostly biliary, mainly in cats [also dogs and pigs] may be multiple, no sig)
- Displacements (congenital or acquired, eg. diaphragmatic hernia)
- Tension lipidosis (focal subcapsular fatty change where liver attaches to diaphragm, may be due to local chronic ischamiea)
- Capsular fibrosis (common older horses due to migrating parasites or foci of non-septic peritonitis)
- Telangiectasis (normal, foci of sinusoidal dilatation esp cats and cattle)
How does passive venous congestion affect the liver grossly and microscopically?
- Enlarged with rounded borders
- Oozes blood on cut surface
- NUTMEG liver (enhanced lobular pattern due to areas of fatty change and congestion)
- Microscopically
> hepatic venules and sinunois engorged
> periacinar areas congested and hepatocytes atrophied
> periportal areas fatty change -> pale colour
Would heart failure persist long enough for the entire liver to degenerate?
No
Give 4 common disorders of of pigmentation
- Melanin (congenital melanosis in calves and lambs, no sig)
- Haemosiderin due to chronic passive venous congestion (nutmeg liver, of potential significance)
- Bile (obstructive jaundice, sig)
- Lipofiscin or ceroid (brown, comes with aging, no sig)
What is hydropic change? Is it common? Is it revesible?
> A vacuolar hepatopathy
Influx of H20 -> cells -> swelling
- Common
- Reversible
What may cause hydropic change?
- hypoxia
- mild toxic damage
- metabolic stress `
What pathologic change may appear similar to hydropic change? What may cause this?
Glycogen accumulation (gylcogenosis) - Hyperadrenocorticsim (Cushings) may cause this
What would be seen with glycogen accumulation? Is this reversible?
Multifocal/diffuse swelling and vacuolation in hepatocytes
- Enlarged pale liver (Severe cases; steroid hepatopathy)
> reversible!
When is lipidosis (fatty liver) seen (4)?
1 - Obesity and starvation (esp cats)
2 - ^ energy demand (pregnancy, lactation, starvation) -> mobilisation of fat stores
3 - Disease (eg. diabetes mellitis, ketosis, pregnancy toxaemia)
4 - Abnormal hepatocyte function (prevents fatty acids complexing protein -> LDL; leading to accumulation)
Is lipidosis reversible?
NO
How common are lysosomal storage diseases?
Rare
What are the causes of lysosomal storage diseases?
- inherited deficiency of lysosomal enzymes -> neuro disease
- macrophages containing stored material accumulate at MULTIPLE sites (LNs, liver, CNS) Liver easiest to biopsy [may be diagnosed at PM]
How common is amyloidosis?
Uncommon
What is the pathophysiology of amyloidosis? What forms exist?
- substance deposited under endothelium and basement membrane of variety of tissues (renal glomeruli, islets of Langerhans, liver)
- 1, 2, endocrine associated
How does amyloidosis appear grossly and mmicrscopically?
- Gross: pale, enlarged and friable liver
- Microscopic: Homogenous acidophilic material
- shows green birefringence when stained with congo red
- results in displacement and atrophy of hepatocytes
What 4 reasons may necrosis occour?
- Ischaemia
- Toxinc damage
- Nutritional deficiencies
- Microbial infection
What are the 3 patterns of necrosis? What pathologies are these associated with?
- Random: EHV-1, salmonella
- Zonal: Ichaemia, toxic damage
- Massive: Hepatosis dietetica
What is hepatosis dietetica?
Vit D and selenium deficiency disorder in pigs
What are the 4 types of fibrosis of the liver?
- Periacinar fibrosis (surrounding central vein, CHF and passive congestion)
- Biliary fibrosis (accompanying inflammation centred on the portal triads (usually infection or inflammation from gut/bile duct)
- Post-necrotic scarring following massive necrosis (rarely seen as usually -> death)
- Cirrhosis = end stage liver disease, hard to ID inciting cause but also irrelevent (extensive fibrotic lesions, +- concurrent nodular regeneration and hyperplasia)
What are the 3 forms of inflammation of the liver?
- Hepatitis (liver parenchyma often cuased by infection)
- Cholangitis (bile ducts, may be immune mediated [esp cats] or associated with infection [eg. salmonellosis in calves]
- Cholangiohepatitis (both)
What does acute hepatitis usually involve? What succeeds it and how does this progress?
- Necrosis
- Succeded by inflammation
- progression =
> complete resolution by regeneration (massive regenerative capacity of liver)
> repair by fibrosis/scarring
> encapsulation by abscessation
> persistence by granulomatous disease
What 3 viruses may cause hepatitis?
- Adenoviruses (canine infection hepatitis)
- Herpesviruses ( EHV-1, infectious bovine rhinotracheitis, feline viral rhinotracheitis, Aujeskys disease
- Coronaviruses (feline infectious peritonitis)
Which animals are commonly affected by viral hepatic disease?
Young and unvaccinated
Which animals does canine infectious hepatits affect?
Young dogs
What type of virus causes infectious canine hepatitis?
Adenovirus
How is infectious canine hepatitis shed? Is this long or short term shedding?
Urine - long term
What tropism does the infectious canine heptitis virus show? How does this manifest? Other clinical signs?
- Endothelium -> Widespread haemorrhage, esp serosal surfaces and hepatocytes (may appear as white spots in liver)
- LNs and tonsils enlarged and reddened, sometimes haemmorhagic.
- recovering animals may show immune-mediated uveitis with corneal opacity (AB/AG complexes deposited in eye)
Give 4 examples of herpesvirus infection
- Equine viral rhinopneumonitis
- Infectious bovine rhinotracheaitis
- Feline viral rhinopneumonitis
- Aujesky’s disease (multiple spp)
Where are herpesvirus lesions seen? What age of animal?
- Foetuses and neonates - liver lesions seen in aborted foetus or neonates after virus crosses placenta
- Random pinpoint foci of necrosis with intracellular inclusion bodies
- necrosis can also occour in lungs, kidneys, spleen, adrenals
What type of virus causes feline infectious peritonitis? What are the 2 forms?
Enteric coronavirus
- mutates -> systemic vasculitis and effusions
- Pyogranulomatous lesions develop in multiple organs inc liver
> wet (effusion) or dry (granulomatous) forms
What are the 3 routes of infection of bacterial hepatitis (from within the body?)
- Direct extension (from disease in adjacent tissues)
- Haematogenous (umbilical v. if umbilicus infected in young animal; portal v. from alimentary tract in adult; hepatic a. in bacteraemia and septicaemia)
- Hepatic abscessation (particulalry common in cattle; from umbilical infections -> mixed bacteria; from rumenitis due to grain overload and rumen acidoisis)
Give 6 examples of bacterial hepititis. Which species are commonly infected?
- Bacillary necrosis (Fusobacterium necrophorum)
- Infectious necrotic hepatitis [Black Disease] (Clostridium Novyi Type B in sheep ± rarely horses and pigs)
- Bacillary haemoglobinuria (Clostridium Haemolyticum in cattle and sheep)
- Tyzzers disease (Bacillus piliformis in labrodents ± occasionally foals, puppies, kittens)
- Leptospirosis (Dogs, zoonotic)
- Salmonellosis (S. Dublin in calves)
Give 2 causes of bacillary necrosis. Which organism is responsible?
- Umbilical v. infection in calves
- Rumenitis in adults
> Fusobacterium Necrophorum
What may be seen grossly and microscopically with bacillary necrosis?
Gross: Multiple pale foci or necrosis throughout liver, may -> abscess if animal survives acute phase
Micro: Coagulative necrosis with bacteria at periphery
What is the technical name for Black disease? Which organism is responsible for this?
Infectious necrotic hepatitis caused by Clostridium Novyi type B
Which species are most commonly affected by Black Disease?
Sheep (rarely horses or pigs)
Whatpathology is associated with black disease?
- Migrating immature liver flukes precipitate the disease
- Extensive subcut venous congestion (hence black) and oedema
- fibrous peritoneal, thoracic and pericardial fluid. characteristic pale foci of necrosis containing bacteria
- surrounded by rim of haemorrhage
How do animals with black disease most commonly present?
Dead
+ post mortem changes occour quickly
Which organism is responsible for bacillary haemaglobinuria?
Clostridium Haemolyticum
Which species are affected by bacillary haemaglobinuria?
Sheep and cattle
Which pathogen is similar to that which causes bacillary haemaglobinuria and what does this mean? What is seen at pathology?
C. Haemolyticum (bacillary haemaglob) similar to C. Novya (black disease)
= pathogenesis similar to black disease
Pathology seen: large necrotic (pale) focus in liver, haemoglobin staining of kidneys
What clinical signs are associated with bacillary haemaglobinuria?
- Severe anaemia
- Jaundice
- Haemoglobinuria
Which organism is responsible for Tyzzers disease?
Clostridium Piliforme (Bacillus Piliformis)
Which animals are most commonly affected by Tyzzers disease?
- Lab rodents
- May affect foals (1-4wo)
- May affect immunosuppressed dogs and cats
What may be seen grossly and microscopically at PM with Tyzzers disease?
Gross: intestinal lesions hard to find at PM
- Micro: Wheatsheaf appearance of colonies when stained with silver stain
Is leptospirosis zoonotic?
Yes
What does leptospirosis cause and which species are more commonly affected?
Hepatic disease in dogs (inc. vaccinates!)
- Haemolytic anaemia, widespread haemorrhage and icterus
- Hepatocyte dissociation ->cholestasis
- Haemosiderin accumulation 2* to haemolysis
Are vaccinated dogs safe from leptospirosis?
No
Give examples of leptospirosis serovars involved in disease
- Canicola
- Icterohaemorrhagicia
What shape are leptospirosis bacteria?
Corkscrew
Which species are most commonly infected with Salmonella? Which subtype of salmonella?
Calves infected with S. Dublin
What clinical signs are associated with salmonellosis?
- Fever
- Diarrhoea
- Dehydration
WHat pathology is seen grossly and microscopically with salmonellosis?
Gross:
- Severe, often haemorrhagic ileum inflammation
- Pale foci of necrosis in liver (paratyphoid nodules)
Micro:
- Foci of necrosis
- Mixed mononuclear inflammatory cell infiltrate
Is parasitic infection usually a common cause of liver pathology?
No - usually incidental finding
> with the exception of liver fluke
Give examples of parasites that may affect the liver and what would be seen pathologically
- Ascaris suum migration -> milk spot liver in pigs
- Strongyle migration from liver in horses -> fibrous tags on liver and adjacent diaphragm
What are the 2 forms of toxic liver disease?
> acute
- widespread haemorrhage due to consumption of clotting factors and failure to produce clotting factors
chronic (continual ingestion of toxic susbtances eg. ragwort, aflatoxins, copper, drugs, over long periods of time)
- evidence of regeneration and repair eg. fibrosis and biliary hyperplasia
Which drugs are hepatotoxic?
Primidone, sulphonamides, paracetamol for cats
Give 3 pathologies of the gallbladder
- Cholecystitis (inflammation) with salmonellosis, infectious canine hepatitis
- Hyperplasia of the mucosa due to irritation of any kind
- Choleliths (Gallstones) may be incidental or obstructional -> maldigestion
What are the 2 main pathologies of the biliary tree (extrahepatic duct)?
- Obstruction
- parasites, choleliths [rare]
- compression due to local inflammation and neoplasia [common] - Rupture [rare]
- serious as omentum incapable of sealing even small leaks (bile caustic)
- chronic inflammatory process and if infected -> peritonitits
What age and species commonly show hyperplastic disease of the liver? Is this always clinically significant?
Old dogs = nodular hyperplasia (1/2 not significant - no need to remove)
What may be seen grossly and microscopically in nodular hyperplasia?
Gross: spherical nodules varying colour from pale -> dark -> normal liver colour
Micro: cells larger, ^ glycogen
- portal areas still visible in mass
- compression of adjacent tissue
Which species is 1* neoplastic disease of the liver seen?
Cats and dogs (^ lifespan)
What are the 2 types of 1* hepatic neoplasia?
- Derived from hepatocytes (hepatoma, hepatocellular carcinoma) - may resemble normal parenchyma +haemorrhage and necrosis if malignant
- Derived from biliary epithelium (cholangiocellular carcinomas most common) - white, firm , umbilicate
What types of metastatic tumour may affect the liver?
> Haemangiosarcoma
- 1* or metastatic in liver
- other predilection sites = spleen, R auricle of heart
- prevalent in large breeds
2* tumours
- v common inc. melanoma, carcinoma, sarcoma, lymphoma
Give 4 pathologies of the exocrine pancreas
- developmental anomalies
- Pancreatitis
- Pancreatic hyperplasia
- Pancreatic neoplasia
What developmental abnormality of the exocrine pancreas is most common? Which breeds are predisposed? What age are clinical signs seen?
- Hypoplasia
- GSDs and calves
- 1 year old
What are the clinical signs of exocrine pancreas hypoplasia?
- steatohorrea and diarrhoea
- loss of condition despite polyphagia
- pot-bellied
What pathology is seen with exocrine pancreatic hypoplasia?
- intestines distended with bulky fatty ingesta
- lack of fat in mesentry and abdo
- sparse pink pancreatic tissue
- hypoplastic acini microscopically
What is acute pancreatitis also known as?
Acute pancreatic necrosis - medical emergency!!
What are the clinical signs associated with acute pancreatitis?
- shock
- CV collapse
- ^ lipase and amylase levels
- some cases subclinical
What may be found grossly and microscopically with acute pancreatitis?
Gross: chalk like areas of ffat necrosis with local reddening around pancreas
- small amout of blood tinged fluid in abdo with fatty globules on paracentesis
Micro: haemorrhagic oedema and necrosis affecting pancreas and peripancreatic fat [though biopsy RARE]
What condition may follow acute pancreatitis?
Chronic pancreatitis
- > replacement fibrosis and atrophy
- > EPI (steathorrea and loss of condition)
- MAY BE SUBCLINICAL IN CATS AND HORSES*
Is pancreatic hyperplasia of clinical significance? In which species is it most common?
- No clinical signicance
- Commonest in old cats, also seen in old dogs
What may be seen grossly and microscopically in pancreatic hyperplasia?
Gross: white lobules or plaques on surface BUT do NOT distort surrounding tissue and are not encapsulated
Micro: similar to normal glandular tissue
Which forms of pancreatic neoplasia exist? Which is most common?
- Adenoma: extremely rare
- Carcinoma (dogs and cats) highly invasive and infiltrative
- > metastases to liver, peritoneum, abdo LNs, spleen, adrenals often at point of Dx already metastasised
