Necrosis is the death of cells and living tissue. There are 5 main types of necrosis: 1. Coagulative necrosis occurs due to sudden loss of blood flow and results in pale, firm dead tissue that later becomes yellow and softer. 2. Colliquative necrosis involves the breakdown of dead tissue into a semi-fluid material due to enzyme degradation, often seen in infections. 3. Caseous necrosis has a cheese-like appearance and combines features of coagulative and colliquative necrosis, seen in tuberculosis. 4. Fat necrosis occurs when fat cells rupture and release contents, appearing as yellow-white deposits with calcium salts. 5. Fibrinoid necrosis is characterized by fibrin deposition

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NECROSIS
By:
Rohini Surti.
BPT 2ND YEAR

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Definition :
It is defined as a localised area of death of
tissue followed later by degradation of tissue
by hydrolytic enzymes liberated from dead
cells, and it is invariably accompanied by
inflammatory reaction.

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Causes:
▪ Hypoxia
▪ Chemical agents
▪ Physical agents
▪ Immunological injury

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Types:
Depending upon morphology and etiology
appearance there are 5 types of necrosis classified:
1. Cogulative necrosis
2. Colliquative necrosis
3. Caseous necrosis
4. Fat necrosis
5. Fibrinoid necrosis

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1.Cogulative Necrosis:
▪ It is a mostcommontype of necrosis caused by irreversible focal injury.
▪ Most sudden cessationof blood flow (i.e.ischaemic injury).
▪ Oragans affectedare Heart, spleen,kidney.
▪ Grossly: focusof Cogulative necrosis in early stage :pale, firm, slightly swollen, infarct.
▪ In progression:yellowish, softerand shrunken.
▪ Microscopically: Convertionof normal cells into ‘tombstones’
▪ Apperancesat the outlines of the cell.
▪ But their cell type can be recognize But their cytoplasmic and nuclear details are lost

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Cogulative necrosis of kidney.

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2.Colliquative Necrosis(liquefaction) :
▪ In occurs commonly due to ichaemic injury, bacterial or fungal infection.
▪ Hydrolytic enzyme tissue degradation in main reason to cause semi-fluid
material.
▪ Occurs in brain, Abscess cavity.
▪ Grossly: Affectedpart is soft, liquefied center containing necrotic debris.
Later it convert into cyst wall.
▪ Microscopically: Cystic space contain necrotic debris and macrophages.
▪ Cyst wall is formed by proliferating capillaries, inflammatory cells and
gliosis.

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Liquefaction necrosis of brain

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3.Caseous Necrosis :
▪ They are having cheese like appearance.
▪ It is found in center of foci of tuberculosis infection.
▪ It combines feature of both Cogulative & liquefactive necrosis.
▪ Grossly : They resembles dry cheese and soft, granular &
yellowish.
▪ Microscopically : They are structureless, eosinophillic material
having scattered granular Debris of disintegrated nuclei.
▪ The surrounding tissue shows characteristics granuloma to us
inflammatory reaction.

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Caseous necrosis of lymph nodes:

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4.Fat necrosis:
▪ It is a special form of cell death occurring at mainly fat rich anatomic
location in the body.
▪ Ex. Traumatic fat necrosis of breast.
▪ In fat necrosis, there is hydrolysis rupture of adipocytes causing
release of neutral fat which changes into glycerol and free fatty
acids.
▪ Grossly : They appear yellowish white and firm deposit. Formation
of calcium soap imparts giving whity appearance.
▪ Microscopically : The necrosed fat cells have cloudy appearance
and are surrounded by inflammatory reaction.

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Fat necrosis in acute pancreatitis:

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5.Fibrinoid Necrosis :
▪ Characterised by deposition of fibrin like material which has
staining properties of fibrin such as phosphotungistic acid
haematoxylin stain
▪ Encountered by immunologic tissue Injury, autoimmune
disease,etc.
▪ Microscopically: identified by brightly eosinophillic, hyaline like
deposition in vessel wall.
▪ Necrotic focus surrounded by nuclear debris of neutrophils.

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Fibrinoid necrosis in autoimmune
vasulitis

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THANK YOU

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Reference :
Harsh Mohan Textbook of
pathology, 7th edition.