General pathology necrosis

Necrosis and its Types

1. NECROSIS By, Mohamed Faizal Asan DEPARTMENT OF GENERAL PATHOLOGY

2. What is Necrosis of a cell? Necrosis is defined as a localised area of death of a tissue followed by degradation of tissue by Hydrolytic enzymes liberated from Dead cells,It is invariably accompanied by inflammatory reaction

3. What happens in necrosis? 1) Cell digestion by Lytic enzymes : Cells become homogeneous with eosinophilic cytoplasm sometimes it may also ungergo vacuolation or dystrophic calcification.

4. 2) Denaturation of proteins : Nuclear changes happens PYKNOSIS – The nucleus shrinks resulting in condensation of neuclear chromatin. KARYOLYSIS – Dissolution of the nucleus. KARYORRHESIS – The nucleus frangments into granular clumps.

5. Types of Necrosis Coagulative Necrosis Liquefactive Necrosis Caseous Necrosis Fat Necrosis Fibrinoid Necrosis

6. 1.Coagulative Necrosis Most common type of necrosis Occurs due to a focal irreversible injury by Ischemia Common organs affected:Heart,Kidney,Spleen Gross appearance:They appear pale,swollen,yellowish and softer,On progression they become shrunken

7. Coagulative necrosis of a kidney Histological appearance : Conversion of normal cells IntoTombstones .(Main Hallmark) Necrosed cells are swollen and become more eosinophilic

8. 2.Liquefactive Necrosis Also called as Colliquative necrosis Occurs due toIschemic injury and bacterial and Fungal infection. Common Examples:Infract brain,Abscess cavity Gross Appearance:Initially soft with a liquefied centre later a cyst wall is formed.

9. Liquefaction necrosis of a Brain Histologic apperance : Cystic spaces with necrotic debris Macrophages filled with Phagocytsed material.

10. Caseous Necrosis Combination of both Coagulative and liquefactive necrosis Found in centre of foci of Tuberculous infection. Gross Appearance:Resembles dry cheese and are soft,Granular,Yellowish colour .

11. Caseous necrosis of a TB lymph node Histologic Appearance: Necrosed foci that are Structureless,eosinophilic with Granular debris. Consists of Langerhans Giant cells.

12. Fat Necrosis Special form of cell death occuring at two anatomically different locations but morphologically similar lesions. Example:Acte pancreatic Necrosis and Traumatic Necrosis common in Breasts. Gross Appearance:Yellowish white firm Deposits,Formation of ncalcium soaps within the Necrosed foci firmer and chalky white appearance.

13. Fat Necrosis in Acute Pancreatitis Histologic Appearance: Necrosed cells with a cloudy appearance. Formation of calcium soaps within the tissue.

14. Fibrinoid Necrosis Characterised by Depsition of fibrin like material which has the staining properties of Fibrin. It maybe due to various Immunologic tissue injury( Example:Immune complex vasculitis,Peptic ulcer……) Gross Appearance:Local hemorrhage may be seen around the site of Necrosis.

15. Fibrinoid Necrosis in Autoimmune vasculitis Histologic Appearance:Bright eosinophilic Hyaline like deposition near the affected vessel wall. Necrotic focus surrounded by Debris of Neutrophils .

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