Path - Cell Injury - Necrosis
What is caseous necrosis?
"Caseous" = cheeselike * Friable(crumble) white: area of necrosis * Necrotic debris = dead WBCc * Chronic * Associated with poorly degradable lipids of bacterial origin
What is Traumatic necrosis of fat?
* Dystocia * SQ in Inter-Muscular fat @ sternum - recumbent cattle
What is the histology of Liquefactive necrosis?
* Loss of cellular detail * Cells are granular * Eosinophilic and basophilic debris * Neurophil nuclei may dominate nuclear debris * No tissue architecture is preserved
What is necrosis of abdominal fat (cattle)?
* Unknown cause - Mesentery, Omentum, retroperitoneum * Extreme cases intestinal stenosis
What is the histopathy of caseous necrosis?
* necrotic area has eosinophilic granular cell debris with a rim of inflammatory cells * Obliterated tissue architecture * Dystrophic calcification - commonly in center of lesion
What are some patterns of tissue necrosis?
1. Coagulative necrosis 2. Liquefactive necrosis 3. Gangrenous necrosis 4. Caseous necrosis 5. Fat necrosis 6. Fibrinoid necrosis
What is the morphologic appearance of necrosis due to?
1. Denaturation of proteins 2. Enzymatic digestion of the cell * Endogenous enzymes derived from the lysosome of the dying cells * By release of lysosomes content from infiltrating WBCs
What are the 3 types of Fat Necrosis?
1. Enzymatic Necrosis 2. Traumatic necrosis of fat 3. Necrosis of abdominal fat
What causes coagulative necrosis?
Caused by ischemia (decrease of blood supply) in all solid organs except the brain
What is necrosis?
Describes the range of morphologic changes that occur following cell death in the living animal
What is coagulative necrosis?
Form of necrosis in which the architecture of dead tissues is preserved (days) * Ultimately the necrotic cells are removed by phagocytosis by WBCs and digestion by the action of lysosomal enzymes of WBCs
What is the gross appearance of liquefactive necrosis?
Necrotic material is frequently creamy yellow bc of the presence of dead WBCs = pus or pruritic material * Tissue is liquid, off white to tan (other colors would indicate inflammation)
What is"dry" gangrene?
No bacterial superinfection; tissue appears dry
What is ganrenous necrosis?
Not a specific pattern of cell death but begins mostly as coagulative neccrosis likely due to ischemia * Commonly applied to distal extremities involving multiple planes of tissues
What is karyolysis?
Nuclear fading
What is Karyorrhexis?
Nuclear fragmentation
What is pyknosis?
Nuclear shrinkage
What is a sterile abscess?
Process caused by nonliving irritants such as drugs - likely yo turn into firm, solid lumps as they scar, rather than remaining pockets of pus
What does an abscess result from?
Result of body's defense reaction to foreign material
What is the ratio of tissue to formalin used to fix tissue?
1:10 part tissue to formalin
What is an infarct?
A localized area of coagulative necrosis
What is an abscess?
A localized collection of pus (liquefied tissue) in a cavity formed by disintegration of tissues surrounded by fibrous connective tissue
What is "wet" gangrene?
Bacterial superinfection; tissue looks wet & liquefactive * Occurs by actions of degradative enzymes in the bacteria & attracted WBCs
What is enzymatic necrosis (pancreatic necrosis of fat)?
Action of activated pancreatic lipases in "escaped" pancreatic fluid * Neutral fat (lipase -> triglycerides) * Fatty acids + Ca+ -> Calcium soaps
What is a septic abscess?
Infection and release of enzymes from WBCs and infectious agent *majority
What nuclear changes can be seen in necrosis?
Karyolysis, Pyknosis, & Karyorrhexis
What causes an Abscess?
Most common are the pus-forming bacteria like Staphylococcus aureus, which is always the cause of abscesses under the skin * Isolated collection of pus by fibrous tissue * Listeria monocytogenous can also cause
What are the causes of caseous necrosis?
Mycobacterium (common is all vet med), Corynebacterium, Fusobacterium, fungal infections
What is Polio used to describe?
Necrosis of only the grey matter in the brain
What is liquefactive necrosis?
Necrotic architecture is "liquefy" =liquid * Dead cells are "digested" resulting in transformation of the tissue into a liquid viscous mass
When is Liquefactive necrosis seen?
Seen in focal bacterial and occasionally fungal infections * Microbes stimulate the accumulation of WBCs & the liberation of enzymes from these cells
What are the 2 types of abscesses?
Septic and Sterile
What is malacia?
Softening of tissue
What is Fibrinoid necrosis?
Special for of necrosis usually seen in immune rxns involving blood vessels * Ag-Ab complexes deposited in the walls of arteries * Glassy, eosinophilic fibrin like material is deposited within the vascular walls
When does liquefactive necrosis occur?
Tissue with high NO recruitment and enzymatic release with digestion of tissue and tissues with high lipid content
