necrosis

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Related to caseous necrosis: granuloma, tuberculosis, Fibrinoid necrosis

necrosis

1. the death of one or more cells in the body, usually within a localized area, as from an interruption of the blood supply to that part
2. death of plant tissue due to disease, frost, etc.

Necrosis

 

the death within the living organism of individual organs or their component tissues or cells.

A necrosis is classified according to the pathological condition that causes it. Thus, frostbite and burns can cause traumatic necrosis; neurotropic necrosis arises with syringomyelia and the nervous form of leprosy; infarcts and gangrene are associated with circulatory, or ischemic, necrosis; caseous necroses occurring in tuberculosis and syphilis are forms of septic necrosis; and fibrinoid necrosis associated with allergic diseases is a type of allergic necrosis.

Necrosis is accompanied by characteristic changes in the cell and in the intercellular substances. The nucleus shrinks and coagulates, a process known as pycnosis, and the cytoplasm breaks up into clumps. The cell eventually lyses, that is, it degenerates and dissolves. The lysis is due to the activation of the lysosomal hydrolytic enzymes, such as ribonuclease, deoxyribonuclease, and acid phosphatase. The activation of the lysosomes occurs as a result of an increase in the permeability of the cell membranes, changes in the osmotic equilibrium, and acidosis—an abnormal increase in the intracellular hydrogen-ion concentration. Fibrinoid changes appear in the connective tissue, and nerve fibers become fragmented and disintegrate into clumps.

The clinical and morphological manifestations and further consequences of necrosis depend on the localization and distribution of the necrosis and on the mechanisms and conditions of origin. The following types of advanced necrotic conditions can develop: dry necrosis, such as Zenker’s degeneration of infected muscles; colliquative, or liquefactive, necrosis, which occurs for example, when a focus of softening arises in the brain in response to cerebral hemorrhage; gangrene; and bed sores. Necrotic tissue tears away; then, either connective tissue grows through it or the necrotic tissue undergoes autolytic or purulent liquefaction. Finally, the necrotic tissue becomes encapsulated and petrified.

The two most serious consequences of necrosis are a loss of function owing to the death of the structural elements of the necrotic tissues or organs and poisoning caused by the actual presence of a necrotic focus and by the inflammation that arises in response to this presence.

V. V. SEROV

necrosis

[nə′krō·səs]
(medicine)
Death of a cell or group of cells as a result of injury, disease, or other pathologic state.
References in periodicals archive ?
It is a necrotising granulomatous infection, which cytologically demonstrates the microscopic equivalent of caseous necrosis, granular-appearing necrotic background, together with mature lymphocytes, epithelioid histiocytes and multinucleated Langhans type histiocytes.
Caption: Figure 4 Histopathology showing tuberculous granuloma with caseous necrosis.
Tissue sections stained by Ziehl--Neelsen showed numerous acid-fast bacteria in the foci of caseous necrosis (Fig.
Tb diagnosis was confirmed by chest radiograph (presence of pleural fluid), Ziehl-Neelsen staining, mycobacteria culture and positive histopathology for granulomas with caseous necrosis.
Plasma cells in caseous necrosis of nerves in leprosy.
Five cases presented with epithelioid granuloma with caseous necrosis with or without positive acid-fast stain; four cases presented with epithelioid granuloma with positive acid-fast stain; two cases presented with chronic inflammation with positive acid-fast stain; 19 cases presented with epithelioid granuloma without positive acid-fast stain; 44 cases presented with chronic inflammation.
1) associated with calcifications and central areas of caseous necrosis (Fig.
Histopathologic examination of laparosopic biopsy materials revealed caseous necrosis of the peritoneal lymph nodes.
A--Heart granuloma showing epithelioid cells and lymphocytes between cardiomyocytes (autopsy exam, HEx100); B--Liver granuloma showing giant and epithelioid cells and lymphocytes in the periphery; some of the hepatocytes display macrovesicular steatosis (autopsy exam, HEx100); C--Caseating granuloma of the pancreas showing caseous necrosis, epithelioid cells and lymphocytes in the periphery next to normal acini (autopsy exam, HEx100); D--Caseating granuloma of the kidney medulla showing caseous necrosis, giant cells and lymphocytes (autopsy exam, HEx100); E--Caseating granuloma of the spleen (autopsy exam, HEx100).
In our observation of this patient, histologic examination revealed granulomas potentially linked to sarcoidosis and a nonspecific, amorphous eosinophilic material that was not caseous necrosis.
Histology of the deep biopsy specimen identified features of granulomatous inflammation and palisading epithelioid cells, Langhans' giant cells, lymphocytes, and a few neutrophils with small foci of caseous necrosis (figure 1).
Granulomatous formations, that surround infected cells and caseous necrosis, are an evidence of cellular response against mycobacteria infection.