Liver and Pancreas Pathology Flashcards
Repeated injury to the liver leads to what?
Loss of normal tissue and loss of function
Scar tissue/fibrosis (irreversible)
What are the important functions of the liver?
Protein Synthesis - clotting factors and albumin Metabolism - detoxification (ammonia - HE)
Excretion and digestion - bilirubin and bile
Nutrition - regulation of fat and carbohydrate
Is the liver well or poorly oxygenated?
Poorly oxygenated
What % of the liver blood flow is taken up by the portal vein? What about the hepatic artery? What travels through each of those vessels?
- Portal vein (nutrients, 75%)
- Hepatic artery (oxygen, 25%)
How many mm in diameter is a classic lobule?
2mm
What makes up a portal triad?
Portal vein, hepatic artery, bile duct
Where in the liver is bile produced? Which way does bile flow through bile ducts in relation to blood flow?
Bile is produced in canaliculi and flows in opposite direction through bile ducts
Where do hepatocytes converge?
central vein
Label this hepatic lobule
What are these 3 zones of the hepatic lobule? Which is the most poorly oxygenated?
Which hepatic zone is the worst affected in toxic injury? Why?
Centrilobular zone - metabolic enzymes capable of changing toxin into more (or less) toxic molecule are located here
Label this portal triad
What is a portosystemic shunt? Which animals does this commonly occur in?
Portal bloodflow bypasses liver and enters systemic circulation
Dogs and Cats
What are the 2 main causes of portosystemic shunts?
Congenital
Acquired
Describe a congenital portosystemic shunt? What happens to the liver?
- Usually single shunt to vena cava/azygous/renal vein
- Liver is bypassed and does not receive blood supply and cannot grow to normal size (atrophies)
Describe an acquired portosystemic shunt? What does this occur secondary to? How does this differ from congenital shunt?
- Secondary to fibrosis in older animals
- Multiple thin-walled shunts
- Slow development of shunts, fibrosis causes scarring and liver becomes so scarred due to repeated damage that it doesn’t allow new blood to come in (portal hypertension, liver congestion) and blood finds another route by creating thin-walled little veins for blood to travel
What is the end result of a liver shunt?
Hepatic encephalopathy
What is this?
Fatty Liver
List congenital/developmental disorders which lead to liver pathology
Congenital cysts
Displacements
Tension lipidosis
Capsular fibrosis
Telangiectasis
How can you tell if liver is enlarged?
Rounded capsular edges
Cutting through reveals rounded edges
What are some degenerative liver hepatopathies?
Vacuolar hepatopathies
Lipidosis (fatty liver)
Amyloidosis
What does “vacuolar hepatopathies” mean? What are the different types? Which of these is reversible? What are the causes?
Anything which causes swelling and vacuolation of hepatocytes
Can be water (hydropic change), fat (lipidosis), glycogen (glycogenesis)
Hydropic change = reversible
Causes - hypoxia, mild toxic damage, metabolic stress, steroid administration/HAC
What is another name for hepatic lipidosis? How does lipidosis occur? What can cause lipidosis?
Fatty Liver
Can be caused by obesity/starvation, stress, increased energy demand (pregnancy, lactation), Disease (diabetes mellitus, ketosis, pregnancy toxemia)
What is amyloidosis? Which breed of cat is highly susceptible?
Abnormal protein buildup which can accumulate in many organs
Can be primary, secondary or endocrine-associated
Oriental cats - see liver rupture associated with amyloid accumulation
What can cause centrilobular necrosis in the liver?
Ischemia
Anemia
Metabolic/Toxic damage
What causes ZONAL pattern of injury to the liver?
Ischemia/Toxic damage
What causes RANDOM pattern of injury to the liver? Give an example
Viral/Bacterial
Usually an “-itis” - Ex. multifocal random hepatitis
What causes FOCALLY EXTENSIVE pattern of injury to the liver?
Bacterial
What causes MASSIVE pattern of injury to the liver? Give an example
Severe injury/toxicity
Ex. hepatosis dietetica (low selenium, high fat)
How does the liver respond to injury (clinically vs pathologically)?
Clinical - Jaundice, Hemorrhage, Edema, HE
Pathology - Regeneration, Fibrosis (firm)
What has happened to this liver? What is the name for this condition?
Liver cirrhosis
What is the name for this condition? How does this occur? What is usually the cause?
Nutmeg liver usually as a result of right sided heart failure
Hepatic venules and sinusoids congested, centrilobular atrophic hepatocytes (dark red) vs periportal fatty change (pale red)
What are the 3 types of liver inflammation?
Hepatitis
Cholangitis
Cholangiohepatitis
What is hepatitis? What is it often caused by?
Inflammation of liver parenchyma (often caused by infection)
What is cholangitis? How does it occur?
- Inflammation of bile ducts - may be immune mediated (cats) or associated with infection (Ex. salmonellosis in calves)
What is cholangiohepatitis?
Inflammation of parenchyma and bile ducts
Acute hepatitis generally involves what kind of change to the liver?
Necrosis followed by inflammation
If animal survives acute hepatitis what are the progression options after that point?
- Complete resolution by regeneration
- Repair by fibrosis and scarring
- Encapsulation by abscessation
- Persistence by granulomatous disease
What are the causes of viral hepatitis? What animals does disease usually occur in?
Adenoviruses (CAV-1)
Herpesviruses (EHV-1, IBR, FVR, Aujesky’s Disease aka pseudorabies)
Feline Infectious Peritonitis (Mutated coronavirus)
Young or unvaccinated animals
What is infectious canine hepatitis caused by?
Canine Adenovirus (CAV-1)
How infectious is canine hepatitis? Through which bodily fluid is it shed? For what tissue does this virus have a tropism and what does that cause? What are the clinical signs?
- Highly infectious - young dogs
- Long term urine shedding
- Endothelium tropism (widespread hemorrhages)
- Lymph nodes and tonsils enlarged, reddened +/- hemorrhagic
What is a unique symptom of animals recovering from canine adenovirus?
Immune mediated uveitis with corneal opacity
What is a unique symptom of animals recovering from canine adenovirus?
Immune mediated uveitis with corneal opacity
Which of the herpesvirus infections can cause abortion in horses?
Equine Viral Rhinopneumonitis
What is another name for Aujesky’s Disease? What animals does it affect? What is VERY important to remember about Aujesky’s Disease?
Pseudorabies (Herpesvirus)
Dogs, Pigs, Cattle, Sheep and Cats
NOTIFIABLE
What types of lesions do herpesviruses cause? In what animals are these lesions seen?
Pinpoint foci of necrosis with intranuclear inclusion bodies (liver lesions)
Seen on PME in aborted fetuses/neonates
Where do herpesviruses cause necrosis?
Lungs, Kidney, Spleen, Adrenal glands
What are the 3 routes of infection for bacterial hepatitis? Give a bit of detail about each
Direct Extension (to adjacent tissues)
Hematogenous (Ex. arteries/veins from infected organs or through umbilicus/umbilical vein)
Abscessation (common in cattle)
What is happening here? How does ruminal acidosis in cattle lead to this occuring?
Give the common causes of bacterial hepatitis? Which of these are zoonotic?
Bacillary necrosis - Fusobacterium Necrophorum
Black’s Disease (Infectious Necrotic Hepatitis) - Clostridium Novyi Type B
Bacillary Hemoglobinuria - Clostridium Hemolyticum
Tyzzer’s Disease - Clostridium piliformis
Leptospirosis - ZOONOTIC
Salmonella - ZOONOTIC
Listeria - ZOONOTIC
What bacterial hepatitis infection does this look like? How can you tell (Hint: think of the name)
Describe the gross pathology. How does it look on microscopy?
Bacillary necrosis caused by Fusobacterium necrophorum - “Necrotic = necrophorum”
Multiple pale foci of necrosis throughout the liver
May develop into abscesses if the animal survives
Coagulative necrosis with bacteria at periphery
What is the etiology of fusobacterium necrophorum in calves vs. adult cattle?
Calves - umbilical
Adult cattle - rumenitis
What bacterial infection does this look like? How can you tell? Describe the pathology. What would you see under the microscope?
Black’s Disease caused by Clostridium novyi type B (Infectious Necrotic Hepatitis)
BLACK tissue = black’s disease
Pathology:
- Extensive subcut venous congestion (Blacks Disease) and Edema
- Fibrinous peritoneal, thoracic and pericardial fluid
Microscopically:
- Pale foci of necrosis (containing bacteria) surrounded by a rim of
hemorrhage
Which condition can precipitate Black’s Disease?
Liver fluke (fasciola hepatica)
Causes a disruption in the environment in the liver, which leads to a proliferation of anaerobic bacteria (clostridium novyi)
What is blackleg in cows? How does it come out of dormancy in the cow?
Clostridium chauvyoei - Infection occurs when animals ingest bacterial spores while grazing. The bacterial spores penetrate the intestine and are disseminated via the bloodstream to the skeletal muscle, then possibly dislodged by bumping into walls, which brings the infectious spores out of dormancy
What bacterial infection does this look like? How can you tell? Describe the pathology. What other bacterial infection is this similar to? What are the clinical signs associated with this disease?
Bacillary hemoglobinuria - Clostridium hemolyticum
Causes focally extensive hepatic necrosis and hemoglobin staining of kidneys (hence the name HEMOlyticum)
Infection of cattle and sheep
VERY similar pathogenesis to C. novyi
Clinical signs - severe anemia, jaundice, hemoglobinuria
What disease gives this classic appearance? Describe these lesions. What is the appearance on microscopy?
Tyzzer’s Disease
“Wheat sheaf” appearance of colonies when stained with silver stain
Which animals are affected by Tyzzer’s Disease? What is the bacteria which causes this disease?
Rodents, Immunosuppressed dogs/cats, Foals (1-4 weeks old)
Tyzzer’s Disease caused by Clostridium piliformis
What bacterial infection causes this appearance? What is the serotype in calves? What is the cause of these pinpoint lesions? What is the name for the nodules seen on histology?
Salmonellosis - S. dublin in calves
Pale pinpoint foci of necrosis in liver “paratyphoid nodules”
True or False - Bacterial infections will tend to cause focally extensive/abscessating lesions?
False
True or False - Viral infections will tend to cause focally extensive/abscessating lesions?
True
True or False - Pinpoint necrosis CANNOT be viral or bacterial
False
What are the features of acute intoxication (toxic liver disease)? Examples?
Hemorrhages - ↑consumption and ↓synthesis clotting factors by damaged liver, jaundice
- Ex. blue-green algae, iron, cresols
What are the features of chronic intoxication (toxic liver disease)? Examples?
- Continual low dose toxic compounds
- Regeneration and repair (fibrosis and biliary hyperplasia)
- Ex. ragwort, aflatoxins and copper
- Certain drugs: Primidone, sulphonamides, paracetamol (cats)
How do you know this is a benign neoplasm? Which animal is this common in?
Common in older dogs
What is the gross pathology of nodular hyperplasia? (Shape, color)
Spherical nodules in the liver
Vary in color from pale to dark or can be same color as rest of the liver
Describe what you would see on microscopy of nodular hyperplasia?
How do cells within the mass compare to normal cells of the liver?
What does the nodule do to the normal tissue of the liver?
Cells are larger, may contain more glycogen
Portal areas still visible within the mass
Compression of adjacent normal tissue
How can you tell the difference between primary and metastatic tumors of the liver?
Primary - usually 1 (can be more) large growths
Metastatic - usually many small focal growths (metastatic shower)
What are the most common primary tumors of the liver? Which animal(s) do they primarily occur in?
Principally dogs and cats
Hepatocellular adenoma or carcinoma
Tumor of biliary epithelium (cholangiocellular carcinoma in cats)
What do cholangiocellular carcinomas typically look like?
White, firm, umbilicate
Is this a primary or metastatic tumor?
Primary tumor
What is this tumor? What causes the dark red color of this tumor?
Hemangiosarcoma
Dark red color = filled with blood, irregular blood-filled channels
Is hemangiosarcoma usually primary or metastatic? Which breeds is this prevalent in? What tissues in the body have a predilection for this tumor?
Both!
Prevalent in large breeds
Predilection for spleen and right auricle
What are the metastatic tumors which commonly spread to the liver as their second site?
Melanoma, Carcinoma, Sarcoma, Lymphoma
What is the name for this and what is this caused by? What animal does this occur in?
Milk Spot on liver caused by Ascaris suum
Strongyle migration in the horse
What is this condition?
Pancreatic Acinar Atrophy
What animals are most commonly affected by pancreatic acinar atrophy?
GSD’s and calves
How does pancreatic acinar atrophy occur? When do clinical signs develop? What are the typical clinical signs?
Developmental anomaly
Clinical signs develop at ~1yr of age (steatorrhea - fat in stools, diarrhea, loss of condition, polyphagia, pot-bellied appearance)
Lack of abdominal fat
Intestines distended (bulky, fatty ingesta)
What would you find on microscopy of the Sparse pink pancreatic tissue found in an animal with pancreatic acinar atrophy?
hypoplastic/atrophic acini
Why does steatorrhea occur in animals with pancreatic acinar atrophy?
Fat in feces - no lipase in the GIT to break down the fat
What is the synonym for acute pancreatitis?
Acute pancreatic necrosis
Describe these lesions (gross and microscopy). For gross, the release of WHAT causes the lesions?
What condition is this associated with?
Acute pancreatitis
Gross - chalk-like fat necrosis (saponification) and reddening caused by release of TNF (tumor necrosis factor) lipase and amylase when pancreas is in shock
Microscopy - hemorrhagic edema and necrosis affecting pancreas and peripancreatic fat
What are these lesions indicative of?
Chronic pancreatitis
How does chronic pancreatitis develop in dogs?
Bouts of acute pancreatitis –> replacement fibrosis/atrophy –> exocrine pancreatic insufficiency (steatorrhea and loss of condition)
In what animals is chronic pancreatitis typically subclinical?
Cats and Horses
What is this?
Pancreatic Hyperplasia
Does pancreatic hyperplasia have any clinical significance? What animals is this most common in? Describe the gross and microscopic appearance?
Nodular hyperplasia common in older dogs and cats - No clinical significance
Gross - White lobes/plaques projecting from the surface (do not distort tissue and not encapsulated)
Microscopy - similar to normal glandular tissue
What is the most common form of pancreatic neoplasia? What about the most rare?
Common - Carcinoma
Rare - Adenoma
What animals does carcinoma affect? How invasive is this tumor? Describe where it metastasizes?
Dogs and cats
Highly invasive, infiltrative with metastases to the liver, peritoneum, abdominal lymph nodes, spleen, adrenals
