Necrosis is the death of cells and living tissue. There are several types of necrosis based on etiology and appearance: 1. Coagulative necrosis occurs when cells die but retain their shape. The dead cells may be replaced by regeneration or fibrosis. 2. Liquefactive necrosis involves tissue degradation by hydrolytic enzymes, forming a soft area containing debris. 3. Caseous necrosis is seen in tuberculosis, appearing like dry cheese and containing structureless debris amid granulomatous inflammation. 4. Fat necrosis results from lipase action in adipose tissue, appearing as yellowish deposits of calcium soaps. 5. Fibrinoid necrosis involves deposition of fibrin-like

1. NECROSIS
DR PREETI AGRAWAL

2. 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 ;
accompanied by inflammatory reaction

3. Causes
Hypoxia
Chemical agents
Physical agents
Microbial agents
Immunological injury etc.

4. Types of necrosis : based on etiology and
morphological appearance , five types
Coagulative necrosis
Liquefactive necrosis
Caseous necrosis
Fat necrosis
Fibrinoid necrosis

5. Coagulative necrosis
•Cells have died but the basic shape and
architecture of the tissue endures
•Most common manifestation of ischaemic
necrosis in tissues.
•Affected tissue maintains solid consistency.
•In most cases the necrotic cells are ultimately
removed by inflammatory cells.
•The dead cells may be replaced by regeneration
from neighboring cells, or by scar (fibrosis).

6. MORPHOLOGY
Grossly :
Early stage – area of necrosis is pale , firm ,
slightly swollen.
Late stage – area becomes yellowish , softer
, shrunken
Microscopically : Outlines of cells are
retained and cell type can still be recognised
but their cytoplasmic and nuclear details are
lost.
The necrosed cells are swollen and have
more eosinophilic cytoplasm than normal

7. Normal Necrosis

8. LIQUEFACTION ( COLLIQUATIVE ) NECROSIS
•Occurs commonly due to ischaemic injury and
bacterial or fungal infections
•Hydrolytic enzymes in tissue degradation have
dominent role in causing semifluid material
•Egs. infarct brain , abscess cavity

9. Grossly : affected area is soft with liquefied centre
containing necrotic debris later, cyst wall is formed
Microscopically : cystic space contains necrotic
debris and macrophages filled with phagocytosed
material.
The cyst wall is formed by proliferating capillaries ,
inflammatory cells , proliferating glial cells or
fibroblasts

10. LIQUIFACTION NECROSIS OF BRAIN

12. CASEOUS NECROSIS
•Accumulation of amorphous (no structure) debris
within an area of necrosis.
•Tissue architecture is abolished and viable cells
are no longer recognizable.
•Characteristically associated with the
granulomatous inflammation of tuberculosis. Also
seen in some fungal infections.

13. Grossly : foci of necrosis resemble dry cheese and
soft , granular and yellowish.
Microscopically : center of necrosed focus contain
structurless , eosinophilic material having
scattered granular debris of disintegrated nuclei .
The surrounding tissue shows granulomatous
inflammatory reactions consisting of epithelioid
cells , interspesed langhans’ and foreign body giant
cells and peripheral mantle of lymphocytes.

14. Caseous necrosis

16. FAT NECROSIS
•Results from the action of lipases released into
adipose tissue.
egs. pancreatitis, trauma.
•Free fatty acids accumulate and precipitate as
calcium soaps (saponification).

17. Grossly : it appears as yellowish white and firm
deposits. Formation of calcium soaps imparts
necrosed foci firmer and chalky white appearance.
Microscopically : Fat cells have cloudy appearance
and surrounded by inflammatory reaction .
formation of calcium soaps is identified as
amorphous , granular and basophilic material .

18. FAT NECROSIS

20. FIBRINOID NECROSIS
Fibrinoid necrosis is characterized by deposition of
fibrin like material.
Egs. Immunologic tissue injury (immune comlex
vasculitis , autoimmune diseases, arthus reaction )
, arterioles in hypertension , peptic ulcer etc.
Microscopically : it is identified by brightly
eosinophilic , hyaline like deposits in vessel wall
.surrounded by nuclear debris of neutrophils.