Necrosis

NECROSIS : the sum of the morphological alterations appearing after both apoptosis and oncosis and caused by the progressive degradative action of enzymes; it may affect groups of cells or part of a structure or an organ. In the case of oncosis, this typically involves broad zones of cells while, in the case of apoptosis, the cells and/or the fragments are often phagocytized prior to their death by adjacent macrophages or parenchymal cells. In either case, the changes converge to a pattern that involves

intracellular morphology :

mitochondrial swelling
mitochondrial flocculent densities and/or calcification
disruption of plasmalemmal continuity
pyknosis : a thickening, especially degeneration of a cell in which the nucleus shrinks in size and the chromatin condenses to a solid, structureless mass or masses.

karyopyknosis : shrinkage of a cell nucleus, with condensation of the chromatin into a solid, structureless mass or masses
pyknotic bodies : bodies in the mucus of stools in amebiasis; they are the nuclear remains of tissue cells and leukocytes

karyoclasis / karyoklasis : the breaking down of the cell nucleus or nuclear membrane

karyorrhexis : rupture of the cell nucleus in which the chromatin disintegrates into formless granules which are extruded from the cell

karyolysis : a form of necrobiosis in which the nucleus of a cell swells and gradually loses its chromatin
karyomegaly : abnormal enlargement of the nucleus of a cell, not caused by polyploidy
karyomere : a vesicle containing only a small portion of the typical nucleus, usually following abnormal mitosis

tissue morphology :

coagulation, coagulative, avascular or ischemic necrosis : necrosis in which tissue becomes a dry, opaque, eosinophilic mass containing the outlines of anucleated cells, resulting from the denaturation of proteins following acute hypoxia

gummy necrosis
Zenker's degeneration / hyaline necrosis : necrosis and hyaline degeneration of striated muscle
acute anoxia => infarct / infarction from obstruction of circulation to the area

Aetiology

embolic infarct : one caused by an embolus.
thrombotic infarct : one caused by a thrombus

Macroscopic anatomy

anemic, pale or white infarct : an area of necrosis in a tissue produced by sudden arrest of circulation in a vessel

Localizations

hemorrhagic or red infarct : an infarct that is red in color owing to the oozing of red corpuscles into the dead area

Pathogenesis

fibrinous thrombembolism : the embolus moves
side circulation is started late, when capillaries are necrotic
venous hypertension (only in lung)

Localizations

pulmonary infarction (principally)
ischemic stroke

bland infarct : an uninfected infarct
septic infarct : one in which the tissues have been invaded by pathogenic organisms.
calcareous infarct : a deposit of calcium salt in the tissues.
uric acid infarct : a deposit of uric acid crystals in the renal tubules of the newborn.
cystic infarct : an infarct enclosed in a membrane.

Shapes of infarcted areas

triangular in lungs, liver, kidneys
nontriangular in encephalon, myocardium

chronic anoxia => vacuolar degeneration => fibrosis

Localizations

myocardioangiosclerosis

colliquative necrosis / liquefaction necrosis : necrosis in which the necrotic material becomes softened and liquefied.

caseation necrosis / cheesy necrosis / caseous necrosis / caseation : necrosis in which the tissue becomes a soft, dry, crumbly mass resembling cheese
tyromatosis : a condition characterized by caseous degeneration.
dry necrosis : that in which the necrotic tissue becomes dry.
fibrinoid necrosis
gangrenous necrosis : cell death caused by a combination of ischemia and superimposed bacterial infection, combining the features of coagulation and colliquative necrosis.
pressure necrosis : necrosis due to insufficient local blood supply as in decubitus ulcers.
necrosis progrediens / progressive sloughing : progressive formation or separation of necrotic tissue in from viable portions of the body.
radiation necrosis / radionecrosis : destruction of tissue caused by radiation
septic necrosis : necrosis resulting from bacterial infection.

eschar : a slough produced by a thermal burn, by a corrosive application, or by gangrene. Also used to indicate the lesion seen in certain rickettsioses (tache noire)

gangrene : death of tissue, usually in considerable mass and generally associated with loss of vascular (nutritive) supply and followed by bacterial invasion and putrefaction

circumscribed gangrene : gangrene that is clearly separated from normal tissue by a zone of inflammatory reaction.

epidemic gangrene / necrosis ustilaginea : dry gangrene from ergotism.

gas gangrene / gaseous gangrene / mephitic gangrene / emphysematous gangrene / clostridial myonecrosis : an acute, severe, and painful condition in humans and other animals, often resulting from dirty, lacerated wounds in which the muscles and subcutaneous tissues become filled with gas and a serosanguineous exudate. The condition is due to histotoxic infection by anaerobic bacteria, among which are Clostridium perfringens , Clostridium novyi , Clostridium septicum , Clostridium sporogenes , and other species of Clostridium. Related conditions in domesticated animals are malignant edema, blackleg, and braxy
dry gangrene / mummification necrosis : necrosis occurring without subsequent bacterial decomposition, the tissues becoming dry and shriveled.

atherosclerotic gangrene : dry gangrene caused by vascular sclerosis

humid gangrene / moist gangrene : necrosis of tissues, with proteolytic decomposition resulting from bacterial action

diabetic gangrene : moist gangrene, usually of the feet, in persons with diabetes mellitus , due to neuropathy, angiopathy, and other complications

progressive gangrene : gangrene in which an effective limiting zone of inflammatory reaction does not form.
senile gangrene : dry gangrene affecting the extremities of the elderly.
symmetric gangrene : gangrene of corresponding digits on both sides, due to vasomotor disturbances.

Aetiology :

primary gangrene / cold gangrene : gangrene without preceding inflammation of the part.
secondary gangrene / hot gangrene / inflammatory gangrene : a form that follows local inflammation.

sympathetic gangrene : gangrene that results from some primary condition
static gangrene / venous gangrene : gangrene that results from stasis of blood in a part.
embolic gangrene : that which follows the blocking of the blood supply by an embolism.
pressure gangrene : gangrene due to pressure, as in decubitus ulcer.
thrombotic gangrene : gangrene from thrombosis of an artery.
traumatic gangrene : gangrene that occurs as a consequence of accidental injury.
trophic gangrene : gangrene due to lesion of the trophic nerve supply of a part

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