Necrosis refers to cell death and the morphological changes that follow. There are several types of necrosis that can occur depending on the mechanism of cell death, including coagulative, liquefactive, caseous, and gangrenous necrosis. Coagulative necrosis is the most common type and results from ischemia, where the architecture of dead tissue is preserved for weeks before being phagocytosed.

3.  Necrosis refers to a spectrum of Morphological
changes that follows cell death
 Enzymatic digestion of cell
 Denaturation of intracellular protein

4.  Membrane damage
 Increased esinophilia
 Glassy homogenous appearance
 Vacuolated cytoplasm – moth eaten
appearance
 Intra cytoplasmic myelin figures

5.  Karyolysis
 Pyknosis
 Karyorhexsis

6.  Epithelial cells stain
evenly pink
(eosinophilic) in
cytoplasm, with
purple, basophilic,
nucleic acids
confined to the
nuclei
 Apical surfaces are
ciliated
 Interstitia not
infiltrated with
immune cells nor
congested with
proteins

7.  Increased
eosinophilic staining
 Decreased
basophilic staining
(RNA)
 Plasma membrane
rounding, blebbing,
loss of cilia, due to
loss of connections
with cytoskeleton
 Integrity of tubules
degrading, but
basement
membranes intact
 Nuclei largely intact,
slightly narrowed,
pyknotic

8.  Cellular
fragmentation
 Loss and fading of
nuclei--karyolysis
 Burst membranes
 Loss of tissue
architecture

10.  Coagulative necrosis
 Liquefactive necrosis
 Caseous necrosis
 Gangrenous necrosis
 Fat necrosis
 Fibrinoid necrosis

11.  Most common
 Caused by ischemia
 Heart , kidney , spleen
 May also in viral hepatitis , thermal burns
 Architecture of dead tissue is preserved
 Esinophilic anucleate cells persist for weeks
 Phagocytosed

12. Denaturation vs enzymatic digestion

14. When there is marked cellular injury, there
is cell death and necrosis. This microscopic
appearance of myocardium shown here is
a mess because so many cells have died
that the tissue is not recognizable. Many
nuclei have become pyknotic (shrunken
and dark) and have then undergone
karyorrhexis (fragmentation) and
karyolysis (dissolution). The cytoplasm
and cell borders are no longer
recognizable. In this case, loss of the blood
supply from a major coronary artery led to
ischemia and cell death.

15. Here is myocardium in which the cells are
dying as a result of ischemic injury from
coronary artery occlusion. This is early in
the process of necrosis. The nuclei of the
myocardial fibers are being lost. The
cytoplasm is losing its structure, because
no well-defined cross-striations are seen.

16. Gross, cross section: A pale, whitish infarct is surrounded by a zone of hyperemia
(vascular dilatation).
Very low power glass slide: The area of coagulative necrosis is bright pink compared to
the lighter pink viable myocardium. The bluish areas on each side of the necrotic zone
represent the granulation tissue response to the necrosis.

17.  Rapid softening and liquefaction
 Hydrolytic enzymes
 Infection
 Ischemic necrosis in brain
 Creamy yellow necrotic material

19.  Variant of coagulative necrosis
 Mc in tuberculosis
 Friable white infracted tissue
 Architecture ?
 Collection Fragmented lysed cells
 Amorphous granular debris
 Distinctive inflammatory border
 Granuloma

21.  Common in clinical practice
 Usually lower limb
 Form of coagulative necrosis
 Types – 1.dry
2.wet

22.  Dry gangrene – variant of coagulative necrosis
 Wet gangrene - liiquefactive superimposed on
coagulative

25.  Enzymatic fat necrosis
 Traumatic fat necrosis

26. Cellular injury to the pancreatic acini leads to
release of powerful enzymes which damage fat by
the production of soaps, the chalky white areas seen
here on the cut surfaces. Microscopically, the
necrotic fat cells at the right have vague cellular
outlines, have lost their peripheral nuclei, and their
cytoplasm has become a pink amorphous mass of
necrotic material. There are some remaining
steatocytes at the left which are not necrotic.

28.  Special form of necrosis
 Immune reactions in blood vessles
 Immune complex with fibrin deposition
 Bright pink amorphous appearance in H.E
 Causes
malignant hypertension
SLE ,RA,HSP,PAN,HBV
acute rheumatic fever