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.
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

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

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

necrosis

[nə′krō·səs]
(medicine)
Death of a cell or group of cells as a result of injury, disease, or other pathologic state.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Histopathological examination is essential to complement the investigation of cutaneous TB cases, however, in this study, the most common histological finding in cutaneous TB was the granuloma in the dermis/ subcutis (73.3% cases), whereas granuloma with caseous necrosis was found in 16.7% cases.
Caption: FIGURE 2: Core needle biopsy showing caseous necrosis and stain for AFB positive.
Confirmatory diagnosis was made by biopsy and histopathology in all cases reported in literature with typical granulomatous lesion with caseous necrosis surrounded by epithelioid and Langhans-type giant cells.
The prostate tissue biopsy showed granulomatous inflammation and focal necrosis; no AFB were seen and caseous necrosis was not noted.
According to histopathological diagnosis, the great majority of amyloidosis cases were diagnosed as having caseous necrosis representing 5/9 (55.5%), followed by fibrosis, sinus hyperplasia, and lymphoma, constituting 2/9 (22.2%), 1/9 (11.1%), and (11.1%), respectively, as indicated in Figure 1.
On fine needle aspiration cytology (FNAC), a granulomatous lesion with caseous necrosis was taken as a case of BTb.
Mycobacterium tuberculosis was isolated on a culture, and a histopathological examination revealed caseous necrosis with granuloma formation (Figure 4).
A granuloma can have different morphological forms, including solid granuloma comprising of macrophages without necrosis or a granuloma with caseous necrosis in the center surrounded by lymphocytes and macrophage12.
On histopathological examination of the lymph node showed characteristic granulomatous lesions showing caseous necrosis in the centre, and a prominent cuff of lymphocytes and plasma cells at the periphery.
Granulomatous inflammation with central caseous necrosis surrounded by epithelial cells and Langhans giant cells was noted in the histopathologic examination of the left middle ear mucosa.
Tissue reactions in the terminal stage were typical tuberculosis granulomas in only 20% of cases, and in the remaining 80%, there were many foci of nonreactive caseous necrosis.