The spectrum of morphological changes that leads to cell death within a living tissue Cell death due to an irreversible cell injury

1. Necrosis
Quick Review

2. Necrosis
 The spectrum of morphological changes that
leads to cell death within a living tissue
 Cell death due to an irreversible cell injury

4. Mainprocesses
occurin
necrosis
 Degeneration of intracellular proteins
 Enzymatic digestion of cells

5. Early
morphological
changesin
necrosis:
Cytoplasm
 Increased eosinophilia
 Glassy homogenous appearance (due to
loss of glycogen )
 Vacuolated cytoplasm ( moth-eaten
appearance)

6. Early
morphological
changesin
necrosis:
Nucleus
 Pyknosis - nuclear shrinkage &
condensation
 Karyorrhexis - fragmentation
 Karyolysis - chromatin fades

9. Typesof
necrosis
Liquefactive necrosis
Coagulative necrosis
Caseous necrosis
Fat necrosis
Gangrene necrosis
Tumour necrosis
Fibrinoid necrosis

10. Coagulative necrosis

11. Coagulative
necrosis
 Default pattern of necrosis
 Associated with ischemia or hypoxia
 In every organ in the body except the
brain

12. Coagulative
necrosis
MACROSCOPIC APPEARANCE
 Tissue is firm
 Architecture is maintained for few days
after cell death
MICROSCOPIC APPEARANCE
 Preserved cell outlines without nuclei

13. Coagulative
necrosis

14. Coagulative
necrosis

15. Coagulative
necrosis
Renal tubule

16. Coagulative
necrosis:
Examples
Myocardial infarction
Renal infarction

17. Liquefactive necrosis

18. Liquefactive
necrosis
 Due to the infection, inflammatory cells
accumulate
 Secrete lysosomal hydrolytic enzymes
 Cells become lysed/ digested/ liquefied
 Digested tissue is removed by
phagocytosis

19. Liquefactive
necrosis
MACROSCOPIC APPEARANCE
 Tissue is in a liquid form
 Sometimes creamy yellow because of pus
formation
MICROSCOPIC APPEARANCE
 Lots of neutrophils
 Cell debris

20. Liquefactive
necrosis

21. Liquefactive
necrosis

22. Liquefactive
necrosis:
Examples
Focal bacterial & fungal infections
Hypoxic cell death in the CNS

23. Fat necrosis

24. Fatnecrosis
 Damaged cells release digestive enzymes
 Break down lipids
 Generate free fatty acids

25. Fatnecrosis
MACROSCOPIC APPEARANCE
 Chalky white areas
MICROSCOPIC APPEARANCE
 Annucleated adipocytes
 Basophillic calcium deposits

26. Fatnecrosis

27. Fatnecrosis:
Example
Pancreatitis

28. Caseous necrosis

29. Caseousnecrosis
 A unique type of cell death seen with
tuberculosis
 Rare otherwise

30. Caseousnecrosis
MACROSCOPIC APPEARANCE
 White, soft, cheese like appearance
MICROSCOPIC APPEARANCE
 A uniformly eosinophilic center (necrosis)
 surrounded by a collar of lymphocytes &
activated macrophages (giant cells,
epithelioid cells).
 “Granuloma”

31. Caseous
necrosis:
Example
Tuberculosis

32. Caseous
necrosis

33. Caseous
necrosis

34. Fibrinoid necrosis

35. Fibrinoid
necrosis
 Immune complex and fibrin deposition in
vessel wall

36. Fibrinoidnecrosis
MACROSCOPIC APPEARANCE
 Usually no gross changes
MICROSCOPIC APPEARANCE
 Fibrin deposition within vessel wall,
pinkish red

37. Fibrinoid
necrosis

38. Fibrinoid
necrosis:
Example
 Autoimmune vascular disease
 polyarteritis nodosa

39. Gangrene necrosis

40. Gangrene
necrosis

41. Gangrene
necrosis
MACROSCOPIC APPEARANCE
 Skin dead and black
MICROSCOPIC APPEARANCE
 Initially, as in coagulative necrosis
 – dry gangrene
 If there is an infection, as in liquefactive
necrosis
 – wet gangrene

42. Thank You!