digest on pathomorhology

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Macroscopically, the affected organs are often enlarged and firm and have a waxy appearance. If the deposits are sufficiently large, painting the cut surface with iodine imparts a yellow color that is transformed to blue violet after application of sulfuric acid.

The histologic diagnosis of amyloid is based almost entirely on its staining characteristics:

H & E. Amyloid by light microscopy with haematoxylin and eosin staining appears as extracellular, homogeneous, structureless and eosinophilic hyaline material

Metachromatic stains (Rosaniline Dyes). Amyloid has the property of metachromasia, i. e. the dye reacts with amyloid and undergoes a color change. Metachromatic stains employed are rosaniline dyes such as methyl-violet and crystal-violet, which impart rosepink coloration to amyloid deposits.

Congo red. All types of amyloid have affinity for Congo red stain. The stain may be used on both gross specimens and microscopic sections amyloid stains an orange color. The stain can also be used to distinguish between AL and AA amyloid (primary and secondary amyloid respectively). After prior treatment with permangnate on the section, Congo red stain is repeated: in the case of primary amyloid (AL amyloid), the Congo red positivity (congophilia) persists while it turns negative for Congo red in secondary amyloid (AA amyloid).

Sulfated alcian blue. This is a nonspecitic screening test and imparts blue-green color to amyloid positive areas.

lmmunohistochemistry. More recently, immunohistochemical stains can classify type of amyloid. Antibody specific for fibril protein gives positive immunoreactivity.

Diagnosis of amyloidosis

Histologic examination of biopsy material is the commonest and confirmatory method for diagnosis in a suspected case of amyloidosis. If renal manifestations are present, kidney is the preferred site for biopsy. Otherwise the commonly accessible sites such as rectum, gingiva, and more recently abdominal fat, are biopsied and are followed by Congo red staining for confirmation.

Pathologic changes in organs

Amyloidosis of Kidneys

Amyloidosis of the kidneys is most common and most serious because of ill-effects on renal function.

The deposits in the kidneys are found in most cases of secondary amyloidosis and in about one third cases of primary amyloidosis.

The kidneys may be normal-sized, enlarged or terminally contracted due to ischemic effect of narrowing of vascular lumina. Cut surface is pale waxy and translucent.

Amyloid deposition occurs primarily in the glomeruli though it may involve peritubular interstitial tissue and the walls of arterioles as well:

a)In the glomeruli, the deposits initially appear on the basement membrane of the glomerular capillaries, but later extend to produce luminal narrowing and distortion of the glomerular capillary tuft.

b)In the tubules, the amyloid deposits likewise begin close to the tubular epithelial basement membrane.

c)The vascular involvement affects chiefly the walls of small arterioles and venules, producing narrowing of their lumina and consequent ischemic effects.

Amyloidosis of Spleen

Two patterns are observed:

“Sago spleen”. The splenomegaly is not marked and cut surface shows characteristic translucent pale and waxy nodules resembling sago grains and hence the name. Microscopically, the amyloid deposits begin in the walls of the arterioles of the white pulp and may subsequently replace the follicles.

“Lardaceous spleen”. There is generally moderate to marked splenomegaly (weight up to 1 kg). Cut surface of the spleen shows map-like areas of amyloid. Microscopically, the deposits involve the walls of splenic sinuses and the small arteries and in the connective tissue of the red pulp.

Amyloidosis of Liver. The liver is often enlarged pale, waxy and firm. The amyloid initially appears in the space of Disse, but later as it increases; it compresses the cords of hepatocytes.

Amyloidosis of Heart.

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Heart is involved in systemic amyloidosis quite commonly more so in the primary than in secondary systemic amyloidosis. It may also be involved in localised form of amyloidosis in very old patients.

Amyloidosis of the heart may produce arrhythmias due to deposition in the conduction‟s system. The heart shows tiny nodular deposits of amyioid underneath the endocardium.

Later, there may be a pressure atrophy and impaired ventricular function, which may produce restrictive cardiomyopathy.

Amyloidosis of Alimentary tract. Involvement of the gastrointestinal tract by amyloidosis may occur at any level from the oral cavity to the anus. Rectal and gingival biopsies are the common sites for diagnosis of systemic amyloidosis.

The prognosis for patients with generalized amyloidosis is poor. Those with immunocytederived amyloidosis have a median survival of 2 years after diagnosis.

Stromal vascular fatty degenerations

Stromal fatty infiltration is the deposition of mature adipose cells in the stromal connective tissue. The condition occurs most often in patients with obesity.

As a rule it is a generalized process when the amount of fat in the depots increases.

Depending on the excess of the patient mass compared to the norm, 4 degrees of obesity are defined:

1.If the patient‟s mass increases by 20 -29% we distinguish 1st degree of obesity;

2.If the patient's mass increases by 30 -49% - 2nd degree;

3.If the patient's mass increases by 50 - 99% - 3rd degree;

4.If the patient's mass increases by 100% and more 4th degree of obesity.

The two commonly affected organs are the heart and the pancreas.

The damage to these organs is most serious.

Subepicardial fat covers the heart as a case, invades the myocardial stroma causing atrophy and sclerosis.

If the connective tissue does not grow, heart rupture in the area of fat growth may occur.

In pancreatic lipomatosis beta-cell atrophy and diabetes mellitus are possible.

According to the etiology the following types of obesity are defined:

1.Primary (idiopathic);

2.Secondary.

There are several types of secondary obesity:

1.Alimentary.

2.Cerebral.

3.Endocrine.

4.Hereditary in Gierke‟s disease.

According to the patient's appearance, obesity may be

1.Symmetrical

2.Upper

3.Medial

4.Lower.

According to morphological peculiarities of adipose tissue, it may be:

1.Hypertrophic.

2.Hyperplastic.

In hypertrophic type adipose tissue enlarges due to increased volume of fatty cells, in hyperplastic due to increase in their number. Obesity is a severe complication of mainly endocrine and nervous diseases. Alimentary obesity is also unfavorable for the organism. As a rule such patients develop ischemic heart disease.

Local enlargement of adipose tissue (lipomatosis) occurs in Dercum's disease when painful fat nodes appear in the subcutaneous fat of the lower and upper extremities and trunk.

Sharp reduction in the amount of neutral fat in the whole organism is called cachexia.

Disturbance in cholesterol and its esters metabolism causes atherosclerosis. The wall of the vessel is thicken everywhere, but much more it is thicken because of the formation of the atherosclerotic plaque, which are composed with lipids and fibrotic tissue.

Stromal vascular carbohydrate degenerations

Stromal vascular carbohydrate degenerations develop due to disturbance of glycosaminoglycans and glycoproteids metabolism. When glycoproteid metabolism is disturbed,

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chromotropic substances are released from the protein bonds. They accumulate in the main substance of the connective tissue. Collagen fibers change into mucus-like mass.

Connective tissue mucin is associated with:

Mucoid or myxoid degeneration in some tumors (myxomas).

Neurofibromas, soft tissue sarcomas etc.

Myxomatous change in the dermis in myxedema.

Myxoid change in the synovium in ganglion on the wrist.

The condition results in colliquative necrosis with formation of cavities filled with mucus.

Mucopolysaccharidoses (MPS)

Disturbance of glycosaminoglycans (GAG) is due to hereditary factors as in a storage disease.

It is characterized by deficiency of specific lysosomal enzyme involved in the degradation of mucopolysaccharides or glycosaminoglycans.

Syndrome of MPS manifests in infancy or early childhood and involves multiple organs and tissues, chiefly connective tissues, liver, spleen, bone marrow, lymph nodes, kidneys, heart and brain.

The mucopolysaccarides accumulate in mononuclear phagocytic cells, endothelial cells, smooth muscle cells and fibroblasts.

The material is finely granular and PAS-positive by light microscopy.

By electron microscopy, it appears in the swollen lysosomes and can be identified biochemically as mucopolysaccharide.

The most frequent of them are Pfaundler-Hurler disease, or gargoilism. Its cause is congenital defect of the enzyme determining GAG metabolism. This disease is characterized by irregular skeleton growth, “massive” skull, heart defects, inguinal and umbilical hernias, hepatoand splenomegaly, keratoleukoma (retina opacity).

PATHOLOGY OF PIGMENTS

Pigments are colored substances, some of which are normal constituents of cells where as others are abnormal and collect in cells only under special circumstances.

Pigments are generally classified into two broad categories:

Endogenous pigments, which are normal constituents of cells and tissues;

Exogenous pigments introduced into the body from environment.

Classification of endogenous pigments

1.Hemoglobinogenic pigments.

2.Proteinigenic.

3.Lipidogenic.

Pigments derived from hemoproteins appear as a result of physiologic destruction of erythrocytes.

Physiologic pigments

1.Ferritin is a ferroproteide. It is located in liver, spleen, bone marrow and lymphatic nodes.

2.Hemosiderin is iron-containing pigment. Hemosiderin, which is formed by aggregates of ferritin and is identifiable by light microscopy as golden-yellow to brown, granular pigment, in the mononuclear phagocytes of the bone marrow, spleen and liver. Hemosiderin is ferric iron that can be demonstrated by Prussian blue reaction

3.Bilirubin is iron-free pigment.

Pathologic pigments

1.Hematoidin is iron-free, orange-brown crystal pigment. It‟s formed extravascularly in the center of hemorrhages or foci of necrosis at anaerobic conditions.

2.Hematin is a brown-black pigment derived from hemoglobin and has 2 types:

Chloric hematin is formed in gastric erosions and ulcers as a result of interaction between hemoglobin and gastric excretion (muriate acid).

Hemomelanin is a brown pigment produced by malarial parasites from hemoglobin; it‟s taken up by monocytes in the blood and subsequently deposited in the liver and spleen.

3.Porfirin is precursor of hem. It deposits in blood and urine. Clinical symptoms are photophobia, erythema, and dermatitis. Spleen, bones, teeth, urine becomes of dark red. Porphyria develops when porphyrin metabolism is disturbed. It may be congenital and acquired. Acquired porphyria is

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observed in intoxications, avitaminosis (pellagra), pernicious anemia, and diseases of the liver.

Pathology of hemosiderin’s metabolism

Hemosiderosis

Hemosiderosis occurs in two situations:

Local hemosiderosis.

It is characterized by local breakdown of red cells in tissues, e.g. in internal hemorrhage.

Mechanism of local hemosiderosis is extravascular hemolysis.

It occurs regularly around areas of bruising and hemorrhage.

In each instance the pigment is localized in cells of the reticuloendothelial system.

In the lungs hemosiderin-laden macrophages (siderofages) are appropriately referred to as

“heart failure cells”.

Visceral siderosis (systemic hemosiderosis).

Mechanism of systemic hemosiderosis is intravascular hemolysis.

It is seen in the liver, spleen and sometimes in kidneys in cases of hemolytic anemia, and in patients requiring repeated blood transfusion. The generalized form of this condition also referred to as secondary hemochromatosis.

The pigment imparts a deep brown color to tissues and organs when it is present in high concentrations.

It can also occur in patients with chronic ineffective erythropoiesis (such as thalassemia major).

Alcohol ingestion when carried to extremes can lead to hemosiderosis because of the augmentation of iron uptake by alcohol.

In hemochromatosis, a genetic disorder, the absorbtion of iron is virtually uncontrolled. The system becomes overload and iron is deposited as hemosiderin in many sites, the main ones being:

-Pancreas – associated with fibrosis, which may destroy islet tissue (diabetes mellitus).

-Liver – usually associated with fibrosis (cirrhosis).

-Skin – mainly around swet glands. Excessive melanin is also deposited; hence this condition is sometimes termed “bronzed diabetes”.

-Heart musle.

-Mesenteric lymph nodes.

Pathology of bilirubin’s metabolism

Jaundice

When the bilirubin content of the serum rises above 34 mmol/l, jaundice appears.

Types of jaundice

1. Prehepatic jaundice (Hemolytic jaundice) - results from an excessive breakdown of the red blood cell membrane in a variety of conditions, which include:

A genetic membrane defect.

An immune reaction.

Circulating of intravascular toxic substances causing red cell destruction (snake poison).

Hemolytic (familial) jaundice in spherocytosis.

Sickle cell anemia.

Hemolytic disease of the newborn, Rh incompatibility.

Incompatible blood transfusion.

Infections (malaria, clostridial infection, mycoplasma pneumonia, sepsis).

Leukemia.

In these conditions the excessive amount of pigment has not pass through the liver for conjugation. The liver‟s capacity to conjugate it is exceeded, and the level of unconjugated bilirubin rises in the plasma. It can crystallize out in the tissues, in the brain, may cause necrosis. Injury of brain may lead to bilirubin encephalopathy (kernicterus).

2. Intrahepatic jaundice (Hepatocellular jaundice) - results from failure both of hepatocytes to conjugate bilirubin and of bilirubin to pass through the liver into the intestine. Both of conjugated bilirubin and unconjugated bilirubin increase its amount in blood. The liver is light yellowish-green color of saffron (“saffron liver”).

Failure of conjugation may involve:

Hepatocellular jaundice, e.g., viral hepatitis and hypoxic necrosis.

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Drug-induced jaundice, e.g., disturbance of glucoronide conjugation.

Intrahepatic cholestasis, e.g., congenital intrahepatic occlusion, tumors, inflammations, or cirrhosis.

Mushroom, arsenic, phosphorous poisoning.

3.Posthepatic jaundice (Obstructive jaundice) - results from an obstruction of the passage of conjugated bilirubin from hepatocytes to the intestine. Conjugated bilirubin is water-soluble and is excreted in the urine. The liver is dark green.

Obstructive jaundice may appear in the following causes:

Stenosis of extrahepatic bile ducts.

Gall stones in the major ducts.

Pancreatic tumor compression.

Fibrosis involving the small intrahepatic ducts; the bile ducts became distended with conjugated bilirubin, which is reabsorbed.

In the liver, bile pigments may appear:

a)As bile pigment droplets in the hepatocytes.

b)As bile impregnations in necrotic areas.

c)As bile casts (bile capillaries, cholangioles, or bile canaliculi).

d)In Kupffer‟s cells.

Pathology of the metabolism of proteinogenic pigments

Melanin is a normal pigment found in the form of fine brown granules in the skin, choroids of the eye, adrenal medulla, and hair and sometimes in the meninges and intestine.

Melanin is a brown-black pigment synthesized by melanocytes from tyrosine by its oxidation.

After secretion of the pigment, it‟s taken up by adjacent epidermal cells and phagocytic melanophores in the underlying dermis

Ultraviolet radiation stimulates the synthesis of melanin.

Various disorders of melanin pigmentation cause generalized and localized hyperpigmentation and hypopigmentation.

Focal hyperpigmentation: malignant melanoma, nevus, melanosis coli, lentigo.

Nevus is a benign tumor.

Malignant melanoma is a highly malignant neoplasm that invades normal tissues early and widely and that almost invariably terminates in death.

A dysontogenetic malformation (hamartoma) consisting of nevus cells. It‟s frequently presented at birth and grows slowly during puberty.

May be generalized melanin pigmentations: a) Addison‟s disease, b) an adrenocortical insufficiency resulting from destruction of the adrenal cortex, c) chloasma observed during pregnancy, d) chronic arsenical poisoning.

Localised hypopigmentation: a) leucoderma is a partial albinism and is an inherited disorder; b) vitiligo is hereditary local hypopigmentation of the skin, c) acquired focal hypopigmentation from various causes such as leprosy, healing of wounds, syphilis, radiation dermatitis, etc.

Albinism is an inherited generalized disorder of melanin metabolism in which there is a decrease or absence of the pigment in the skin and choroid of the eye. Albinos have blond hair, poor vision and severe photophobia. They are highly sensitive to sunlight.

Pathology of the metabolism of lipidogenic pigments

Lipopigments usually include lipofuscin and lipochrom. Lipofuscin is an insoluble lipid pigment presented in cells of elderly persons and those with mulnutrition or a chronic wasting disease.

It is a brown intracellular pigment found in hepatocytes, cardiocytes, and neurons.

Organs containing large amounts of lipofuscin are deep brown; in the heart, this is referred as brown atrophy.

Exogenous pigments

Inhaled pigments. The most commonly inhaled substances are carbon or coal dust; others are silica or stone dust, iron or iron oxide, asbestos and various other organic substances. Anthracosis (i. e. deposition of carbon particles) is seen in almost every adult lung and generally provokes no reaction of tissue injury.

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Ingested pigments. Chronic ingestion of certain metals may produce pigmentation. Argyna is chronic ingestion of silver compounds. Chronic lead poisoning may produce the characteristic blue lines on teeth. Carotenemia is yellowish-red coloration of the skin caused by excessive ingestion of carrots.

Ingested pigments (tattooing). Pigments like India ink, cinnabar and carbon are introduced into the dermis in the process of tattooing where the pigment is taken up by macrophages and lies permanently in the connective tissue.

Mineral metabolism disturbance

Minerals play an active role in metabolic processes of the human organism. They are components of structural elements of cells, enzymes, hormones, vitamins, and pigments.

The most frequent disturbances in medical practice are in the metabolism of calcium, copper, potassium, and iron.

Calcium metabolism disturbances

I.Dystrophic calcification. Dystrophic calcification refers to the macroscopic deposition of calcium salts in injuried tissues and does not simply reflect an accumulation of calcium derived from the bodies of dead cells. It is often visible to the naked eye, and ranges from gritty, sandlike grains to firm, rock-hard material. Staining with H&E demonstrates calcium salts as deeply basophilic, irregular and granular clumps. For identification of calcium salts we usually use special reaction called silver impregnation method or Kossa‟s method. Calcium deposits are stained black.

It may occur in crucial locations, such as:

1.Necrotic tissue, which is not absorbed:

Old caseous lesions of tuberculosis.

Old infarcts.

Old collections of pus.

Dead parasites (echinococci).

Old thrombi.

Dead fetus (lythopedion).

2.Tissues undergoing slow degeneration:

Hyaline areas in simple tumors.

Tissues in old age, especially fibrous tissue, cartilage, in the mitral or aortic valves after rheumatic fever with formation of mitral or aortic stenosis or as in atherosclerotic coronary arteries with narrowing of those vessels.

II.Metastatic calcinosis (calcium metastases) reflects deranged calcium metabolism associated with increased serum calcium concentration (hypercalcemia). It has systemic character; its main cause is hypercalcemia, which may be of endocrine origin in hyperproduction of Parathormone or hypoproduction of Calcitonine. Calcium salts precipitate in different organs, more frequently in the lungs, gastric mucosa, kidneys, myocardium, arterial walls. It may be associated with:

Reduction of calcium excretion from the organism.

Multiple fractures of the bones.

Hyperparathyroidism.

Chronic renal failure.

Multiple myeloma.

Osteomalacia (when the bone becomes soft).

Lesions of the large intestine (the place of Ca excretion).

Vitamin D intoxication.

The outcome is unfavorable, calcium does not resolve.

Copper metabolism disturbance

This appears in Wilson-Konovalov disease (hepatocerebral degeneration, hepatolenticular degeneration).

It is a hereditary disease in which liver ceruloplasmin production decreases. Ceruloplasmin is alpha2-globulin and can bind copper in the blood. As a result, copper becomes free from unstable bonds with plasma proteins and sediments in the tissue.

Copper accumulates in the liver, brain, kidneys, cornea (in the cornea it looks like greenbrown ring on its margin of the cornea), in the pancreas, testes, etc.

The state is characterized by development of liver cirrhosis, degenerative symmetrical changes in the brain in the area of lens nuclei, caudal body, pale globe, and cortex.

Copper blood plasma amount is decreased but is increased in the urine.

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There are 3 forms of the disease: hepatic, lenticular, hepatolenticular.

The outcome is unfavorable.

Potassium metabolism disturbances

Increased blood (hyperpotassemia) and tissue potassium amount is observed in Addison’s disease and is associated with the lesion of the adrenal cortex, the hormones of which regulate electrolyte exchange.

Potassium deficiency characterizes periodic paralysis; hereditary disease for which attack of weakness and motor paralysis are typical.

Formation of Stones

Stones or calculi are dense formations freely lying in the cavities of the organs or in the ducts.

Their shape depends on the organs in which they are formed: round in the urinary bladder, facet in the gallbladder (their faces are lapped to each other), branching in the kidneys.

Their surface may be either smooth or rough.

The color depends on their chemical composition: white (phosphates), yellow (urates), dark brown or green (pigment).

On cut they may be crystalloid (radial structure), colloid (stratified structure) and colloidcrystalloid (radial-stratified).

Their chemical composition is different, i.e. biliary stones may be cholesterol, pigment, calcium and combined, urinary - urates, phosphates, oxalates (calcium oxalate), cystin, xantin.

Bronchial calculi consist of mucus inlayed with calcium.

Stones are most frequently formed in the bile ducts and urinary tract in cholelithiasis, urolithiasis, in the excretory ducts of the pancreas, salivary glands, bronchi, crypts of the tonsils, veins (phlebolith), intestine (coprolyth).

Both general and local factors are important for pathogenesis of calculus formation. General factors are the main ones; they are acquired or hereditary disturbances of metabolism. Local factors are congestion, inflammation. The immediate mechanism of calculus formation consists of two processes: formation of organic matrix and salt crystallization. Each of these may be primary.

Compression with a stone may result in necroses in renal pelvis, gallbladder, bedsores, perforations, inflammation (pyelocystitis, cholecystitis, cholangitis, etc.).

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IRREVERSIBLE CELLULAR INJURY:

Cell death is a state of irreversible injury. It may occur in the living body as a local change (i. e. autolysis, necrosis and apoptosis), or result in end of the life (somatic death).

Autolysis (“self-digestion”) is disintegration of the cell by its own hydrolytic enzymes liberated from lysosomes. Autolysis can occur in the living body when it is surrounded by inflammatory reaction (vital reaction), or may occur as postmortem change in which there is complete absence of surrounding inflammatory response. Autolysis is rapid in some tissues rich in hydrolytic enzymes such as in the pancreas, and gastric mucosa, intermediate in tissues like the heart, liver and kidney, and slow in fibrous tissue.

Necrosis

Necrosis is celullar death in the living body in the disease. Necrosis is defined as focal death along with degradation of tissue by hydrolytic enzymes liberated by cells. It is invariably accompanied by inflammatory reaction.

Two essential changes bring about irreversible cell injury in necrosis - cell digestion by lytic enzymes and denaturation of proteins.

Nuclear changes. The irreversibly damaged nuclei are characterized by one of the following three features:

1.At first nucleus shrinks and becomes dense. This process is called karyopicnosis.

2.After that karyorrhexis develops. This process is characterised by rupture of nuclear membrane and fragmentation of the nucleus. Nucleus is decomposed into small granules.

3.Also karyolysis may be developed, when the nucleus dissolves.

At electron microscopic level, in addition to the above nuclear changes, disorganization and disintegration of the cytoplasmic organelles and severe damage of the plasma membrane are seen.

In the cytoplasm, protein denaturation and coagulation or hydration and colliquation take place. Plasmorrhexis is characterized by decomposition of cytoplasm into clumps due to coagulation. Then plasmolysis takes place. Plasmolysis is hydrolytic fusion of cytoplasm. Sometimes we can observe vacuolization and calcification in the cytoplasm.

Stages of necrosis (or morphogenesis):

1.Paranecrosis - reversible changes; as a rule, reversible degeneration.

2.Necrobiosis - irreversible degenerative changes.

3.Death of cells.

4.Autolysis is the enzymic digestion of the dead cell due to effect of catalytic enzymes derived from lysosomes.

Types of necrosis

According to the mechanisms of development:

1.Direct (from influence of mechanical, physical, chemical, and toxic factors).

2.Indirect (vascular and neurogenous).

According to the cause:

1.Traumatic.

2.Toxic.

3.Trophoneurotic.

4.Allergic.

5.Vascular or ischemic.

According to the morphological features:

1.Coagulative necrosis is associated with inhibition of lytic enzymes. Foci of coagulative necrosis in the early stage are pale, firm, and slightly swollen. With progression they become more yellowish, softer, and shrunken. The cells do not lyse; thus, their outlines are relatively preserved. Nuclei disappear and the acidified cytoplasm becomes eosiniphilic. Waxy (Zenker‟s) necrosis of muscle may occur at typhoid fever.

2.Liquefactive (colliquative) necrosis is marked by dissolution of tissue due to enzymatic lysis of dead cells. Typically, it takes place in the brain when autocatalytic enzymes are released from dead cells. Liquefactive necrosis occurs also in purulent inflammation due to the heterolytic action of polymorphonuclear leucocytes in pus. Liquefied tissue is soft, diffluent and composed of disintegrated cells and fluid.

3.Gangrene – develops in organs and tissues having contact with environment. The most often examples of gangrene are gangrene of low extremities, uterus, lungs etc.