– Defined as localized area of death of tissue, followed by degeneration of tissue, by hydrolytic enzymes, liberated by dead cells, accomplnied by inflammatory reaction..
– Caused by various agents like hypoxia, chemical agents, physical agents, microbial agents, immunological injury..
1. Coagulative Necrosis:
– common type.
– focal irreversible injury.
– mostly by ischaemic necrosis.
(sudden cessation of blood flow)
– rarely bacterial and chemical
– organs effected are heart, kidney, spleen.
– Microscopically it is the hallmark for conversion of normal cells into ‘tombstones’. (the cytoplasm and other material disappears but cell wall remains)
2. Liquefaction (colliquative) Necrosis:
-ischaemic injury or bacterial infection.
-hydrolytic enzymes causes the material to become semi-fluid.
3. Caseous Necrosis:
– shows features of both Coagulative and Liquefaction necrosis.
– found in centers of foci of tuberculous infection.
4. Fat Necrosis:
– usually seen in breast and acute pancreatitis.
5. Fibrenoid Necrosis:
– immunological tissue injury.
1. Avascular Necrosis:
– of bones….. resulting from ischaemia.
– common condition.
i) common cause:
– sickle cell disease.
– corticosteroid administration.
– radiation therapy.
– chronic alcoholism.
ii) mechanism : interruption of blood supply to bones due to – trauma
2. Lever cell Necrosis:
i) Diffused (submassive to massive)
– Periportal (peripheral)
Refrence: Harsh Mohan textbook of Pathology (seventh edition).