Liver Pathology Flashcards
What cell type is responsible for defending the liver against bacterial and viral agents?
Kupffer cells
What antibody in enterohepatic circulation is responsible for protecting against pathogens?
IgA
What part of hepatocytes are responsible for defense against pathogens?
Phase I in the SER and phase II in the cytosol
What change do injured hepatocytes often undergo?
Hydropic vacuolar change (lipidosis if mild)
Chronic, mild injury to hepatocytes causes what change?
Atrophy
What does apoptosis in the liver look like histologically?
Intensely eosinophilic bodies with well defined borders and a pericellular halo
This pattern of injury consists of foci of varying sizes scattered through lobes
Random
Random pattern injury is usually caused by ___
Infectious agents arriving via the bloodstream
This pattern of injury is seen as all hepatocytes in defined areas of all lobules being affected to approximately the same extent
Zonal
What pattern is associated with a “reticulated” liver?
Zonal
With acute ___ injury, the liver overall will be swollen and friable, with rounded lobular edges
Zonal
The subset of the zonal pattern of injury is the most common, with the least oxygenated hepatocytes around the central vein (zone 3) being affected
Centrilobular
Hypoxia due to right sided cardiac insufficiency, anemia, or shock is a common cause of this pattern
Centrilobular
Bioactivation of xenobiotics from the gut causes free radical damage in this pattern
Centrilobular
This pattern (a subset of zonal) occurs when only part of zone 3 is affected; it generally precedes centrilobular pattern and has the same etiologies
Paracentral
This is the rarest of the patterns (still a subset of zonal) and is most often seen in horses, pigs, and cats; it is mainly due to toxic insult (such as aflatoxin, hexachloraphene, and steroid hepatopathy)
Midzonal (zone 2)
This is an uncommon pattern (subset of zonal) that reflects direct hepatocyte damage by an agent entering from the bloodstream; usually involves a “direct-acting” toxicant that does not require bioactivation
Periportal (zone 1)
This subset of the zonal pattern reflects severe and extensive damage such that zones of damage begin to coalesce
Bridging
This subset of the zonal pattern occurs when the entire lobule is affected; the liver acutely becomes a sac of dilated, engorged sinusoids and then the parenchyma collapses and fibrosis occurs
Massive
Viruses are the least likely to induce this response and fibrosis, while bacteria and parasites are the most likely to induce this response and fibrosis
Inflammatory
This condition is generally associated with an infectious agent and is random in distribution
Acute hepatitis
Viral inducers of acute hepatitis cause ___ and ___ exudate
Necrosis
Light suppurative
Bacterial inducers of acute hepatitis cause ___ and ___ exudate
Necrosis
Heavy suppurative
Coliform bacterial inducers of acute hepatitis cause ___ or ___ exudate
Pyogranulomatous
Granulomatous
Any persistent infectious agent will cause this, in which the agent is surrounded by fibrosis
Chronic hepatitis
This liver condition consists of necrosis and/or apoptosis in midzonal and periportal areas; if not stopped, it can become end stage liver
Chronic active hepatitis
This liver condition is often unnoticed until necropsy of an animal with a systemic infection; neutrophils and lymphocytes are sometimes seen in the portal triads as evidence the liver was dealing with an insult
Reactive hepatitis
This inflammation is centered around and in cholangioles of the portal triad; N0 may be present, but it is more common for lymphocytes, macrophages, and fibrosis to be seen
Cholangitis
This type of hepatitis centers around cholangioles but spreads to periportal hepatocytes; it occurs when agents such as flukes travel up the biliary tree
Cholaniohepatitis
In large scale hepatocyte loss, these stem cells create replacements for the ones lost
Oval cells
Regeneration without scarring occurs rapidly under what two conditions?
Stroma is present and severe collapse has not occured
Inflammation is minimal or nonexistent
(this is often the case in toxicant injury)
Cholangioles respond to any outflow impairment via this method; it is usually associated with longstanding liver damage
Biliary hyperplasia
The supporting stroma of the triads in the liver is a combination of what three types of collagen?
I, III, IV
After chronic and/or repetitive injury, what cells (that normally store triglycerides) redifferentiate into myofibroblastic cells?
Stellate (Ito) cells
What do redifferentiated Ito cells deposit? (2)
Coarse collagen I
Ground substance
This is a diffuse process characterized by fibrosis and the conversion of the normal architecture into structurally abnormal lobules
End stage liver (cirrhosis)
As part of end stage fibrosis, shunts develop between what vessels?
hepatic arterioles and central veins
Regeneration of “normal” hepatocytes in end stage liver can cause what gross lesions? (2)
Macronodular
Micronodular
What species are more prone to macronodular cirrhosis? (3)
Dogs
Cats
Humans
What species are more prone to micronodular cirrhosis?
Horses, sheep, goats, cattle
What type of fibrosis lends to a poor prognosis?
Bridging
Approximately how much liver parenchyma needs to be lost before clinical signs manifest?
3/4
Acute liver failure happens in cases of ___
Massive fibrosis
Chronic liver failure happens as ___ develops
End stage liver
What is the mechanism behind hepatic encephalopathy?
Liver failure -> loss of urea cycle -> ammonia cannot be converted to urea -> ammonia buildup in blood -> ammonia gets into PNS and CNS and damages astrocytes
All clotting factors except ___ are synthesized in the liver; this is why bleeding often occurs in cases of liver failure
VIII
Why does ascites occur with liver failure? (2)
Albumin not produced; cannot maintain oncotic pressure
Shunting causes hypertension, leading to leakage
What is a cutaneous change seen in dogs and cats with liver failure?
Epidermal necrosis and ulceration with parakeratosis
What is a cutaneous change seen in herbivores with liver failure?
Secondary photosensitization (dt buildup of phylloerythrin)
These are normally incidental, can get quite large, reflect abnormal development of the biliary tress, and occur in dogs, cats, and pigs
Biliary cysts
This mainly occurs in large animals when a ligamentous attachment causes hypoxia in an organ
Tension lipidosis
This horse disease’s etiology is debated (Parasites? Residual adhesions between the diaphragm and hepatic capsule? Aliens?) but the lesions associated with it are tags and plaques
Capsular fibrosis (fibrous tags)
A condition of unknown etiology in which hepatocytes drop out and sinusoids dilate to fill the space, becoming irregular and blood filled; common in cattle and old cats
Telangiectasia
This circulatory disorder is almost always a consequence of right sided cardiac insufficiency, with sinusoids engorging from centrilobular to entire lobule. When acute, the liver is swollen, red, spongy, and oozes blood. When chronic, the liver is large, pale, and firm.
Passive congestion - a disease of outflow
This disease is often associated with plant or fungal toxicosis and is characterized by fibrosis around the centrilobular veins, leading to congestion
Veno-occlusive disease
Severe acute ___ will lead to profound centrilobular hypoxia with degeneration and necrosis
Anemia - a disease of inflow
Slowly developing ___ will lead to atrophy of centrilobular hepatocytes
Anemia
Anemia and passive congestion both result in a ___ pattern
Reticular
These may be intra or extra hepatic but usually involve one large caliber between the portal vein and vena cava; intrahepatic more common in large dogs, extrahepatic more common in small dogs
Congenital porto-systemic shunts
Due to abnormal blood supply, this causes the liver to be small with poorly defined lobules, small hepatocytes, indistinct veins, and abundant arterioles
Congenital porto-systemic shunt
Developing secondarily to bridging fibrosis, veno-occlusive disease, abnormally large regenerative nodules, or amyloidosis, this disease impairs flow within the portal venous system leading to pressure buildup and ascites
Portal hypertension
This condition appears grossly as a large, soft, friable, pale yellow liver with a reticulated pattern and greasy texture; it can arise from metabolic disturbances as well as toxic injury
Lipidosis
This condition is pathologic and occurs mainly in dogs with hyperadrenocorticism; the liver will be enlarged and slightly pale with a reticular pattern and normal texture
Glycogen accumulation
Typically occurs in large animals with chronic infections and tends to be peri-sinusoidal; the liver appears smaller, pale brown, and slightly firmer than normal with a waxy texture
Amyloidosis
This condition leads to acute necrosis and inflammation via free radicals, ending in end stage liver in certain sheep and dogs
Copper accumulation
This accumulates in Kupffer cells due to hemoglobin breakdown and may give the liver a blackish color
Hemosiderin
Wear and tear pigment
Lipofuscin
Melanin in the liver of a mammal is reflective of ___
Congenital melanosis (pigment where it shouldn’t be)
Melanin in the liver of a bird, reptile, or amphibian is indicative of ___
Chronic inflammatory disease
This virus in dogs targets hepatocytes and endothelial cells lining sinusoids and appears as an enlarged, friable liver with necrosis and a reticular pattern of small, white foci; there are blue, smudgy inclusion bodies in affected nuclei; edema of the gall bladder wall is almost diagnostic
Canine Adenovirus
This virus induces random foci of necrosis and little inflammation in the liver; it is seen histologically as acidophilic intranuclear inclusion bodies
Herpes
This can be either fibronous/fibrinopurulent and cover the capsular surface or granulomatous/pyogranulomatous and expand out from the triads. Meow.
FIP wet form and dry form
Bacteria causing abscesses can reach the liver via these three routes
Portal system
Umbilicus (neonates)
Lung -> pulmonary veins -> L heart -> hepatic arteries
Aerobic or facultative anaerobic bacteria tend to cause a ___ abscess while anaerobic bacteria tend to cause a ___ abscess
Purely suppurative
Necrotic, foul-smelling, cavitating
Which bacteria are most responsible for abscesses in horses? (2)
Actinobacillus equuli
Listeria monocytogenes
Which bacteria are most responsible for abscesses in cattle? (3)
Arcanobacter pyogenes
Fusobacterium necrophorum
Pasteurella multocida
Which bacteria are most responsible for abscesses in sheep? (3)
Corynebacterium ovis
Haemophilus agni
Pasteurella haemolytica
Which bacteria is most responsible for abscesses in dogs and cats?
Yersinia tularensis
Which bacteria are most responsible for abscesses in rabbits? (4)
Pasteurella multocida
Yersinia tularensis
Listeria monocytogenes
Streptococcus
