necrosis

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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 ?
The 41 preoperative donor liver biopsies revealed 13 hydrops, 8 sinusoidal dilatation, 9 pigment deposition in hepatocytes, and 18 sparse focal necrosis. Microvesicular steatosis between 3-15% was observed in 13 donors and macrovesicular steatosis between 5-25% in 20 donors.
Low-grade MEC have epithelial cells that show keratinization and small lumen forming glandular cells, high-grade MEC have epidermoid and mucinous cells with focal necrosis. (2)
Lesions like congestion, consolidations and focal necrosis were present on the surface of lungs as reported by Yagihashi et al.
Besides, Antroq also prevented the development of focal necrosis, fibrin deposits, prominent leukocyte infiltration, apoptotic figures, and focal matrix accumulation/fibrosis along the arterial wall in the CAL mice.
Liver autopsy specimens of terminal DSS patients generally showed massive or focal necrosis with little or no recruitment of polymorphonuclear cells or lymphocytes (3,4).
Microscopy revealed an infiltrating neoplastic lesion composed of variably-sized anastomosing vascular channels lined by plump endothelial cells with areas of haemorrhage and focal necrosis. In some areas, solid proliferation of the tumour cells with small vascular lumina formation was noted.
Occasionally, increased mitotic activity with atypical mitoses and focal necrosis can be present.
Pathologic examination of the surgical specimen revealed a 20 x 13 x 9-cm primarily solid heterogeneous mass, containing tan-yellow and white areas with focal necrosis, hemorrhage and myxoid change.
The results of our study indicate that toxic doses of APAP may prone rats more susceptible to periportal and focal necrosis. Beta carotene treatment play hepatoprotective role against APAP-induced hepatotoxicity.
(8) Histologically, they appear more aggressive, with nuclear pleomorphism, cytologic atypia, increased mitotic activity, focal necrosis, and lymphatic/vascular invasion.
Clinical conference: management of rare events following dermal fillers - focal necrosis and angry red bumps.