NECROSIS -pathology notes

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 NECROSIS 

DEFINITION:

  • Its defined as the morphological changes taking place in a tissue after cell death due to degradative action f enzymes on irreversibly injured cell.

TYPES OF NECROIS :

A)CASEOUS NECROSIS

B)LIQUEFACTIVE NECROSIS

C)COAGULATIVE NECROSIS

D)FIBRINIOD NECROSIS

E)FAT NECROSIS

F)GANGEROUS NECROSIS




CYTOPLASMIC CHANGES :

  • Increased eosinophilia of cytoplasm 
  • Vacuolation and moth eaten appearance of cytoplasm 
  • Calcification of cell membrane and intracellular structures 
  • Formation of myelin figures 

NUCLEAR CHANGES :

  • KARYOLYSIS : Fading of basophilia of nucleus
  • PYKNOSIS: Nuclear shrinkage due to condensation of chromatin 
  • KARYORRHEXIS -Nuclear fragmentation 

A)CASESOUS NECROSIS :

  • Its seen in tuberculosis and occurs due to both enzymatic degradation of tissue and denaturation of cellular proteins 
  • The tissue architecture is lost and replaced by soft ,creamy cheese like material 
  • Microscopically ,there is amorphous granular debris seen 
  • Examples : tuberculosis lymph node ,tuberculosis lung 

B)LIQUEFACTIVE NECROSIS :

  • Its caused by enzymatic degradation of tissue 
  • The tissue undergoing liquefactive necrosis undergoes softening with destruction of architecture and accumulation of semifluid pus.
  • The cellular outlines of cells in tissue are completely lost
  • Examples: cerebral abscess, spinal cord abscess



C)COAGULATIVE NECROSIS :

  • Its is caused by denaturation of intracellular protein 
  • The cellular outlines of necrosed tissue is maintained 
  • The organ undergoing coagulative necrosis have firm texture 
  • Examples: myocardial infraction, renal infarcts 

D)FIBRINOID NECROSIS :

  • It occurs in walls of blood vessel secondary to injury leading to insudation and accumulation of plasma proteins giving an eosinophilic hue
  • Examples: fibrinoid necrosis of blood vessel in immune and non-immune vasculitis 



F)FAT NECROSIS :

  • Its seen in adipose tissue and is characterized by grey white chalky deposits in fatty tissue 
  • Microscopically ,shadowy outlines of necrotic adipocytes with foreign body giant cells and basophilic calcification deposits are seen 
  • Types-
  • Traumatic fat necrosis seen in breast and buttocks following blunt trauma 
  • Enzymatic fat necrosis seen in acute pancreatitis





F)GANGRENOUS NECROSIS:

  • Its coagulative necrosis of tissue with superadded putrefaction by putrefactive bacteria example clostridium species 
  • Grossly ,the organ is grayish black in color and foul smelling 
  • Examples : intestinal gangrene. gangrene of fingers.


                                                 THANK YOU 


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