1. NECROSIS
1

2. OBJECTIVES
• Highlight the basic concepts and principles
of necrosis (cell death)
• Differentiate between different types of
necrosis
2

3. CONTENTS
4.1 Definition of necrosis
4.2 Different types of necrosis
4.3 Different types of necrosis base on pathologic
changes
3

4. 4.1 Definition Of Necrosis
• Necrosis; defined as focal death along with degradation of tissue by
hydrolitic enzymes liberated by cells. It’s invariably accompanied
by inflammatory reaction.
• Causes; 1. Loss of blood supply - caused by blockage of a vessel by a
blood clot which produces immediate local
anoxia.
2. Bacterial toxins – inflammation is produced & if it’s strong the
result is necrosis.
3. Physical irritants – excessive heat, excessive cold, trauma &
radiation.
4. Chemical irritants – strong acid.
4

5. 4.2 Types Of Necrosis
• Morphologically, 5 types of necrosis are identified:
i) Coagulative necrosis
ii) Liquefaction (Colliquative) necrosis
iii) Caseous necrosis
iv) Fat necrosis
v) Fibrinoid necrosis
• Gangrene is a form of necrosis of tissue with superadded
putrefaction; gangrene necrosis
5

6. i) Coagulative necrosis
 Most common type of necrosis caused by irreversible
focal injury (mostly because ischaemia).
 Less often bacterial & chemical agents.
 The organs commonly affected are HEART, KIDNEY &
SPLEEN.
6

7. Coagulative necrosis – Renal infarction
7

8. Coagulative necrosis – Spleenic infarction
8

9. ii) Liquefaction (Colliquative) necrosis
 Occurs commonly due to ischaemic injury & bacterial or
fungal infections.
 Occurs due to degradation of tissue by the action of
powerful hydrolytic enzymes.
 Examples are INFARCT BRAIN (stroke) & ABSCESS
CAVITY.
9

10. Liquifactive necrosis - Stroke
10

11. Liquifactive necrosis – Liver abscess
11

12. iii) Caseous necrosis
 Found in the centre of foci of tuberculosis infections.
 It combines features of both coagulative & liquefactive
necrosis.
12

13. Caseous necrosis
-Tuberculosis
13

14. Caseous necrosis -Tuberculosis
14

15. iv) Fat necrosis
 Special form of cell death occurring at two anatomically different
locations but morphologically similar lesions.
 These are ACUTE PANCREATIC NECROSIS & TRAUMATIC FAT
NECROSIS (breast).
 In the case of pancreas, there is liberation of pancreatic lipase from
injured or inflamed tissue that results in necrosis of the pancreas.
 Fat necrosis in either of the two instances results in hydrolysis of
neutral fat present in adipose cells into glycerol & free fatty acid.
15

16. v) Fibrinoid necrosis
 Characterized by deposition of fibrin-like material which has the
staining properties of fibrin.
 It’s encountered in various examples of immunologic tissues injury,
arterioles in hypertension, peptic ulcer etc.
vi) Gangrene necrosis
 The type of necrosis is usually coagulative due to ischaemia.
 Is characterized by primarily inflammation provoked by virulent
bacteria.
 3 types; dry, wet & gas gangrene.
16

17. 4.3 Types Of Necrosis Base On
Pathologic Changes
i) Coagulative necrosis
 Grossly: foci of coagulative necrosis in the early stage are PALE, FIRM
& SLIGHTLY SWOLLEN.
: with progression, they become more YELLOWISH, SOFTER
& SHRUNKEN.
Micro: the pattern of microscopic change results from 2 processes
which are DENATURATION OF PROTEINS & ENZYMATIC
DIGESTION OF THE CELL.
17

18. ii) Liquefaction (Colliquative) necrosis
 Grossly: the affected area is soft with liquefied centre containing necrotic
debris.
: later, a cyst wall is formed.
Micro: the cystic space contains necrotic cell debris & macrophages filled
with phagocytosed material.
: the cyst wall is formed by proliferating cappilaries,
inflammatory cells & gliosis (proliferating glial cells) in the
case of brain & proliferating fibroblasts in the case of
abscess cavity.
18

19. iii) Caseous necrosis
 Grossly: resemble dry cheese and are soft, granular & yellowish.
Micro: the necrosed foci are structureless, eosinophilic & contain granular
debris.
iv) Fat necrosis
 Grossly: appears as yellowish-white & firm deposits.
: formation of calcium soaps imparts the necrosed foci firmer &
chalky white appearance.
Micro: necrosed fat cells have cloudy appearance & are surrounded by an
inflammatory reaction.
19

20. v) Fibrinoid necrosis
 Grossly: is identified by brightly eosinophilic, hyaline-like deposition in
the vessel wall or on the luminar surface of peptic ulcer.
: local haemorrhages may occur due to rupture of these blood
vessels.
vi) Dry gangrene
 Macro: the affected part is dry, shrunken & dark black, resembling the foot
: it’s black due to liberation of haemoglobin from haemolysed red
blood cells.
Histo: the separation consists of inflammatory granulation tissue.
20

21. vii) Wet gangrene
 Macro; the affected part is soft, swollen, putrid, rotten & dark.
: the example is gangrene of bowel.
Histo: there is ulceration of the mucosa & intense inflammatory infiltration.
viii) Gas gangrene
 Grossly: the affected area is swollen, edematous, painful & crepitant due
to accumulation of gas bubbles within the tissues.
: the affected tissue becomes dark black & foul smelling.
Micro: at the periphery, a zone of leucocytic infiltration, edema &
congestion are found.
21

22. THANK YOU
22