What is Necrosis??
Necrosis is the morphologic changes that follows cell death in living tissue.
Types of Necrosis
Basic types:
- Coagulative necrosis: Hypoxic death of cells in all tissues except brain, example-infart of heart ( miocardial infraction), kidney, liver,spleen,adrenal gland & other solid organs.
- Liquefative / colliquative necrosis :example - abscess, boil & hypoxic death of brain tissue.
Special types:
- Caseous necrosis : example- granuloma of tuberculosis.
- Fat necrosis :
- Enzymatic fat necrosis : example- enzymatic fat necrosis of pancreas & omental tissue.
- Traumatic fat necrosis : example - traumatic fat necrosis of breast.
3. Fibrinoid necrosis : example
- Acute rheumatic fever.
- Connective tissue disorder, example-rheumatoid arthritis, systemic lupus erythematosus ( SLE), polyarthritis nodosa in arteriols.
4. Gangrenous neceosis : example - any necrosis with auperadded putefaction by bacteria.
What is the causes of necrosis? 
- Ischaemia ( due to thrombosis, embolism,atherosclerosis, and pressure by tumor).
- Infection : example - bacterial, viral, protozoal and fungal.
- Immunologic reaction : example -antigen - antibodybreaction.
- Physical : trauma & burn.
- Chemical : example - arsenic, cyanide.
The microscopic change of necrosis/ state the microscopic examination of necrosis/nucleear changes in neceosis.
Nuclear changes in necrosis :
Nuclear changes appear in any one of three patterns, all due to non apecific breakdown of DNA.
- Karyolyais : The basophilia of the chromatin fades due to DNAse activity.
- Pyknosis : It is thevdegeneration and condensation of nuclear chromatin. Characterized by nuclear shrinkage & increased basophilia.
- Karyorrhexis : The pyknotic nucleus undergoes fragmentation. In a day or two, the nucleus totally disappears
Cytoplasmic changes in necrosis :
The cytoplasm becomes fully eosinophilic & glossy appearance. Sometimes look perforated.
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