necrosis :definition, steps, causes, morphology, morphological patterns, types...

1. Presentation of Aliza
Bibi

2. Necrosis
 The death of most or all the cells in an organ or tissue due to disease,
injury or failure of the blood supply.
 Form of cell injury which results in the premature death of cells in living
tissue by autolysis.
 Caused by factors external to the cell or tissue.

3. There are two steps that occurs when a
cell dies:
1. Proteins inside the cell break down.
2. The body release enzymes that digest these dead
cells.

4. Causes of necrosis:
 Ischemia
 Physical agents
 Chemical agents
 Immunological injury

5. Morphology
cytoplasmic changes:
 Increased eosinophilia of cytoplasm
 Glassy homeogenous appearance
 Cytoplasm is vacuolated
 Calcification of dead cells
 Appearance of myelin figure
Nuclear changes:
 Fading of basophilia of chromatin(Karyolysis)
 Nuclear shrinkage (pyknosis)
 Fragmentation of pyknotic nucleas(Karyorrhexis)

6. Morphological patterns of tissue
necrosis:
1. Coagulative necrosis
2. Liquefactive necrosis
3. Caseous necrosis
4. Fat necrosis
5. Fibroid necrosis
6. Gangrenous necrosis

7. Coagulative necrosis:
 Most common type of necrosis.
 Caused by inadequate blood supply to a region.
 Can affect any tissue in the body except the brain.
 Commonly occurs in major organs like kidney,heart or liver particularly
when oxygen is deprived.

8. Liquefactive necrosis:
 Also called colliquative necrosis.
 Results in transformation of tissue into liquid viscous mass.
 Associated with bacterial or fungal infection.
 Liquefactive necrosis can take place due to certain infection,
neutrophils,will release hydrolytic enzymes which attacks surrounding
tissues.

9. Caseous necrosis:
 Caseous necrosis or caseous degeneration is a unique form of cell death in
which tissue maintains a cheese like appearance.
 Dead tissue appears as a soft and White proteinaceous dead cell.
 Caseous necrosis can also be caused by syphilis and certain fungi.
 Main cause of caseous necrosis is tuberculosis,a disease that causes lung
infection.

10. Fat necrosis:
 Also known as balser’s necrosis.
 Form of necrosis characterized by the action upon fat by digestive
enzymes.
 In fat necrosis the enzyme lipase release fatty acids from triglycerides.fatty
acids then complex with calcium to form soaps.These soaps appear as
white chalky deposits.
 Usually associated with trauma of pancreas.

11. Fibrinoid necrosis:
 Fibrinoid necrosis is form of cellular death that results in the formation of
fibrous tissue, usually occuring in blood vessels.
 Result of very high blood pressure that damage cells in blood vessels,
leading to cell death.
 Causes includes vasculitis and infection due to rejection of organ
transplant.
 Symptoms include blood in urine, blood in stool, nosebleed, bleeding
gums etc.

12. Gangrenous necrosis:
 Gangrenous necrosis refers to the death of tissue due to lack of blood flow.
 Symptoms include change in skin color to red or black,sweeling,pain,skin
breakdown and coolness.
 Feet and hands are most commonly affected.
 Treatment involve surgery to remove dead skin, antibiotics to treat infection.
 Types includes:
1. Dry gangrene
2. Wet gangrene
3. Gas gangrene

14. Thank you….
Any queries….