Necrosis

Necrosis - Definition and their Types

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NECROSIS
By:
Rohini Surti.
BPT 2
ND
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 most common type of necrosis caused by irreversible focal injury.
▪Most sudden cessation of blood flow (i.e.ischaemic injury).
▪Oragans affected are Heart, spleen, kidney.
▪Grossly: focus of Cogulative necrosis in early stage :pale, firm, slightly swollen, infarct.
▪In progression :yellowish, softer and shrunken.
▪Microscopically: Convertion of normal cells into ‘tombstones’
▪Apperances at 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:Affected part 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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▪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, 7
th
edition.