general pathology necrosis

NECROSIS

By,

Mohamed Faizal Asan

DEPARTMENT OF GENERAL

PATHOLOGY

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

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.

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.

Types of Necrosis

Coagulative Necrosis

Liquefactive Necrosis

Caseous Necrosis

Fat Necrosis

Fibrinoid Necrosis

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

Coagulative necrosis of a kidney

Histological appearance :

•Conversion of normal cells

IntoTombstones.(Main Hallmark)

•Necrosed cells are swollen and become

more eosinophilic

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.

Liquefaction necrosis of a Brain

•Histologic apperance:

•Cystic spaces with necrotic debris

•Macrophages filled with Phagocytsed

material.

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.

Caseous necrosis of a TB lymph node

Histologic Appearance:

Necrosed foci that are Structureless,eosinophilic with Granular debris.

Consists of Langerhans Giant cells.

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.

Fat Necrosis in Acute Pancreatitis

Histologic Appearance:

Necrosed cells with a cloudy

appearance.

Formation of calcium soaps within the

tissue.

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.

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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