This document discusses different types of cell death, including apoptosis and necrosis. It describes necrosis as cell death resulting from external factors that cause irreversible injury. The key morphological changes seen with necrosis include increased cytoplasmic eosinophilia, nuclear pyknosis, karyorrhexis, and karyolysis. There are several patterns of necrosis depending on the mechanism and tissue involved, such as coagulative, liquefactive, caseous, and gangrene. Coagulative necrosis preserves tissue architecture while liquefactive necrosis destroys tissue structure. Gangrene refers to visible tissue necrosis, usually due to ischemia.

1. Irreversible Cell injury
(Cell Death)

2. CELLS REACT TO INJURIOUS
STIMULI
• ADAPTING
• SUSTAINING REVERSIBLE INJURY
• SUFFERING IRREVERSIBLE INJURY
AND DYING

4. TYPES OF CELL DEATH
• APOPTOSIS (“normal” death
or physiologic death)
• NECROSIS (“premature” or
“untimely” death due to
“causes”(Pathologic death)

5. NECROSIS
• It refers to a series of morphologic changes that
follow cell death in living tissues
• OR is the gross and light-microscopic
appearances that indicate cell death.

6. • The surrounding living tissue almost
always show inflammatory reaction
• The necrotic cell undergo lysis
• Autolysis is the dead cell being self-
digested by its lysosomal enzymes, while
heterolysis is the cell being digested by
the body's living white cells.

7. Morphology of Necrotic Cells
• Increased Eosinophilia of cytoplasm
- loss of RNA (basophilia)
- denatured cytoplasmic protein bind tightly to
eosin
• Nuclear Changes
- Pyknosis ( shrinkage & ↑ basophilia)
- Karyorrhexis (Fragmentation of pyknotic nuclei)
- Karyolysis (fading of chromatine – DNAase
effect
• Myelin figure (EM)
– large, whorled phospholipid mass (phospholipid
precipitate)

9. HISTOLOGIC FEATURES OF
COAGULATIVE NECROSIS
Normal
Reversible
cell
cell injury Karyorrhexi
with s
cytoplasmic Irreversible
& organelle cell injury with
swelling, rupture of Karyolysis
blebbing & membrane &
ribosome organelles, &
detachment nuclear
pyknosis

10. Myocardial infarction (coagulative necrosis)
Cytoplasmic eosinophilia & nuclear karyolysis

11. Pathogenesis of necrosis
1.Denaturation of intracellular proteins
( structural & enzymatic)
2. Enzymetic digestion of the cell
(Auto & Heterolysis)

12. Morphologic Pattern of Necrotic
Cell mass
TYPES OF NECROSIS
• COAGULATIVE NECROSIS
• LIQUEFACTIVE NECROSIS
• CASEOUS NECROSIS
• FAT NECROSIS
• FIBRINOID NECROSIS
• GANGRENE

13. COAGULATIVE NECROSIS
• Death of groups of cells with preservation of
general tissue architecture-tombstone
appearance for at least a few days.
• Affected tissue is firm due to denaturation of
structural & enzymatic proteins(intracellular
acidosis)
• – Example . Ischemic injury of heart,
kidney, ,spleen.

14. Coagulative necrosis
 Preservation of
structure
 Firm
 Protein
denaturation
 Hypoxic tissue
death (except
brain)

15. Spleen; Coagulative necrosis

16. • The microscopy is distinctive. After loss of their
nuclei, the cytoplasm of the cells remains intact for
days. The "tombstones" reveal the structure of the
living tissue. If the patient lives, the edges of the
necrotic area become inflamed, and eventually the
dead cells will be removed by white blood cells
• RULE: Unless otherwise specified in this section,
the death of a group of cells will result in
coagulation necrosis
• (Ischemic necrosis=Infarction)

17. Kidney infarct exhibiting coagulative necrosis, with loss of nuclei
and clumping of cytoplasm but with preservation of basic outlines
of glomerular and tubular architecture

18. DEATH:
LIGHT MICROSCOPY

19. Morphologic pattern of Necrotic
Cell mass
• Liquefactive Necrosis
- focal bacterial (or fungal) infections
– accumulation of inflammatory
cells
- hypoxic death of cells within CNS

20. LIQUEFACTIVE NECROSIS
• (* "colliquative necrosis" in Europe): When
the cells die, they are rapidly destroyed by
lysosomal enzymes, either their own or
those from neutrophilic leukocytes
• The tissue becomes liquid viscous mass
• Material is creamy yellow in color
• Seen in ischemia of brain, abscess

23. Normal brain Liquefactive necrosis

24. CASEOUS NECROSIS
*Type of coagulative necrosis
*Tissue is cheesy white in appearance
*All the cells in the area die & surrounded by
inflammatory cells (granulomatous
inflammation).
*The tissue architecture is completely
distructed & turn into friable tissue.
*Seen in tuberculous infections &certain
fungal infections (as Histoplasmosis)

25. A tuberculous lung with a large area of caseous
necrosis

26. Caseous necrosis of lymph nodes

28. Caseous necrosis with Giant cells

29. Fat necrosis
 Not a specific pattern
 Focal areas of fat digestion
 Usually via release of lipases from pancreas
 Lipase releases free fatty acid (saponification)
from the local lipids (membranes, depot
triglyceride).
 FFA combine with Ca to produce salt “soaps”

30. Foci of Fat necrosis with saponification in the mesentry . The
areas of white chalky deposits represent calcium soap
formation at sites of lipid breakdown.

31. Microscopic appearance of fat necrosis

32. FIBRINOID NECROSIS
• is a term for damage to the walls of
arteries which allows plasma proteins to
leak out, and precipitate in, the media

33. FIBRINOID NECROSIS

34. GANGRENE
• ("gangrenous necrosis") is not a separate
kind of necrosis at all, but a term for
necrosis that is advanced and visible
grossly. The word gangrene comes from
the Latin word gangraena, an eating sore.
Gangrene is death and decay of a body
part mostly ischemic necrosis of limbs

35. • Gangrene is defined as the gradual destruction
of living tissue, due to an obstruction in the
supply of blood and oxygen to an area of the
body (Ischemia)
• Gangrene = ischemic necrosis

36. TYPES OF GANGRENE
• .DRY GANGRENE
• .WET GANGRENE

37. • Dry gangrene
This is mostly coagulative necrosis
without infection (free of infection). It is
usually brought on by frostbite, or poor
circulation that cause the tissues to
become dry & black.

38. “DRY” GANGRENE

39. dry gangrene (coagulative necrosis)

40. WET GANGRENE
• there's mostly liquefactive necrosis (i.e.,
the typical foul-smelling, oozing foot
infected with several different kinds of
bacteria).

41. "wet gangrene in patient with Diabetes
millitus”

42. Ischemic necrosis of the bowel (bowel infarction)