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Necrosis
Last reviewed: 05.07.2025
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[ What causes necrosis?
Necrosis is caused by reasons that are conventionally divided into endogenous and exogenous. Exogenous factors are: mechanical trauma, exposure to extreme temperatures, electric current, ionizing radiation, acids, alkalis, heavy metal salts, some microorganisms, such as necrobacteria, anthrax, putrefactive microflora.
Endogenous factors are varied and are divided into: vascular, neurohumoral, allergic and metabolic.
Necrosis has 3 stages of development: pre-necrosis (the state of an organ or tissue before irreversible changes occur); death (irreversible cessation of vital activity); destructive changes (decay, removal, delimitation of remnants).
Clinical and anatomical forms: coagulation (dry) necrosis, colliquative necrosis (wet, gangrene, infarction).
Mechanical and thermal injuries mostly cause the development of local processes and local necrosis, without causing a general reaction of the body. Although their prevalence can be from small areas to quite extensive, for example, with burns; as well as the depth of tissue damage.
Dry necrosis is characterized by rapid tissue coagulation with the formation of a dense brown or black scab; around it, edema and hyperemia quickly subside and a clear demarcation line is formed, separating necrosis from healthy tissue. Subsequently, it is slowly rejected with replacement by scar tissue or an ulcer is formed. Infection may join dry necrosis, in which case it turns into wet necrosis.
Wet necrosis develops in the presence of infection or when they form in a moist environment, such as wounds or burns. This necrosis is characterized by the formation of a loose, intimately fused scab of white or dirty gray color; the demarcation line is poorly expressed; the tissues around the scab are edematous and hyperemic; there is a general reaction of the body.
In cases where necrosis affects the entire limb or part of it (for example, a foot with frostbite), as well as an organ or part of it, the pathology is defined by the term "gangrene", for example: gangrene of the foot, limb, lung, intestine, gangrenous cholecystitis, gangrenous appendicitis, etc. Gangrene is based on vascular disorders, primarily arterial. With rapid circulatory disorders, necrosis occurs almost lightning fast. This occurs with arterial thrombosis (rarely veins, for example, thrombosis of the mesenteric vessels), when exposed to microflora, for example, anaerobic. In the case of slow development of circulatory disorders: obliterating atherosclerosis, endarteritis, Raynaud's disease, diabetes mellitus, etc., the pre-necrotic phase is long, accompanied initially by tissue atrophy, and then by the development of gangrene with decompensation of blood flow. One of the forms of gangrene of the skin and subcutaneous tissue are bedsores, which arise due to prolonged compression of tissues in a forced position and disruption of microcirculation in them. Bedsores, and extensive ones at that, occur especially often when the spinal cord is damaged (Bastian's law); in other cases, necrosis is local, and can be multiple, in places of greatest compression of the skin. Gangrene is divided into dry and wet according to its clinical course.
Dry gangrene is usually superficial or affects small distal areas of a limb segment, such as one or more fingers. It is brown or black in color, the demarcation line is well defined, the surrounding tissues, although atrophic, do not show signs of inflammation. There is no general reaction of the body to the process, only manifestations of the underlying and associated diseases.
Wet gangrene of the extremities and internal organs is accompanied by rapid spread of edema and hyperemia, involvement of the lymphatic system in the process, rapid destruction of tissues, increasing general intoxication of the body. Dry necrosis may persist, but edema and hyperemia of tissues develop around it.