necrosis

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Related to central necrosis: Frank necrosis, necroses, necrotized

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 ?
In a study of 124 patients with oral cavity squamous cell carcinoma, Ng et al reported a similar finding--that is, only a minority of cervical metastatic levels with central necrosis were responsible for the false-negative results of FDG-PET, whereas the remaining necrotic levels still yielded positive FDG uptake.
Summary of Clinical, Histologic, and Laboratory Findings Plus Treatment of Levamisole-Induced Vasculitis Clinical presentation Painful, purpuric retiform or stellate rash [+ or -] central necrosis Histologic findings Microvascular thrombi Leukocytoclastic vasculitis Laboratory findings Leukopenia (<4000/[micro]L) Neutropenia (<1500/[micro]L) Positive autoantibodies: ANA, p-ANCA, c-ANCA, LA Treatment Cessation of cocaine use Abbreviations: ANA, anti-nuclear antibody; c-ANCA, cytoplasmic antineutrophil cytoplasmic antibody; LA, lupus anticoagulant; p-ANCA, perinuclear antineutrophil cytoplasmic antibody.
These false negative cases were DCIS (HP--Fragmented core of fibrocollagenous tissue) and Invasive ductal carcinoma with central necrosis and fibrosis.
Proliferative lesions are granulomas composed of compact aggregates of epithelioid cells, lymphocytes, and Langhans-type giant cells with variable degrees of central necrosis and relatively few acid-fast bacilli.
3) We believed that our patient's tumor might have malignant potential because of (1) the infiltration of the capsule without infiltration of adjacent tissues, (2) the widespread central necrosis, (6) and (3) the Ki-67 value of 5 to 10%.
3-cm) multilobulated mass with central necrosis within the left upper abdominal quadrant originating from the tail and body of the pancreas (magnetic resonance imaging).
6 4cm with central necrosis and air lucency in the apical region (Figure-1).
A computed tomography (CT) scan of the abdomen revealed a 15-cm left renal cell carcinoma (RCC) with central necrosis and left renal vein and regional lymph nodes involvement.
Patterns of liver lesion enhancement were: hypervascular homogenous 4, hypervascular heterogenous with peripheral enhancement and central necrosis 15.
Central necrosis frequently develops as the "tumor mass" increases in size.
Computed tomographic scan of the patient's chest showed collapse of the left lower lung with central necrosis, bilateral pleural effusions, and mediastinal lymphadenopathy.
The bulla ruptures and may exude a bloody purulent material, followed by central necrosis, a dark brown or black eschar, and edema out of proportion to the lesion's size.

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