World Library  
Flag as Inappropriate
Email this Article

Tissue necrosis

Article Id: WHEBN0003120827
Reproduction Date:

Title: Tissue necrosis  
Author: World Heritage Encyclopedia
Language: English
Subject: Black Death, Plague (disease), Leukocytosis, Bubonic plague
Publisher: World Heritage Encyclopedia

Tissue necrosis

For other uses, see Necrosis (disambiguation).
Not to be confused with Narcosis.

Necrosis (from the Greek νεκρός, "dead", νέκρωσις, "death, the stage of dying, the act of killing") is a form of cell injury that results in the premature death of cells in living tissue by autolysis.[1] Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma, that result in the unregulated digestion of cell components. In contrast, apoptosis is a naturally occurring programmed and targeted cause of cellular death. While apoptosis often provides beneficial effects to the organism, necrosis is almost always detrimental and can be fatal.[2]

Cells that die due to necrosis do not follow the apoptotic signal transduction pathway but rather various receptors are activated that result in the loss of cell membrane integrity and an uncontrolled release of products of cell death into the intracellular space.[1] This initiates in the surrounding tissue an inflammatory response which prevents nearby phagocytes from locating and eliminating the dead cells by phagocytosis.[2] For this reason, it is often necessary to remove necrotic tissue surgically, a procedure known as debridement. Untreated necrosis results in a build-up of decomposing dead tissue and cell debris at or near the site of the cell death. A classic example is gangrene.


Structural signs that indicate irreversible cell injury and the progression of necrosis include dense clumping and progressive disruption of genetic material, and disruption to membranes of cells and organelles.[3]

Morphological patterns

There are five distinctive morphological patterns of necrosis:

  1. Coagulative necrosis is characterized by the formation of a gelatinous (gel-like) substance in dead tissues in which the architecture of the tissue is maintained,[4] and can be observed by light microscopy. Coagulation occurs as a result of protein denaturation, causing the albumin in protein to form a firm and opaque state.[3] This pattern of necrosis is typically seen in hypoxic (low-oxygen) environments, such as infarction. Coagulative necrosis occurs primarily in tissues such the kidney, heart and adrenal glands.[3] Severe ischemia most commonly causes necrosis of this form.[5]
  2. Liquefactive necrosis (or colliquative necrosis), in contrast to coagulative necrosis, is characterized by the digestion of dead cells to form a viscous liquid mass.[4] This is typical of bacterial, or sometimes fungal, infections because of their ability to stimulate an inflammatory response. The necrotic liquid mass is frequently creamy yellow due to the presence of dead leukocytes and is commonly known as pus.[4] Hypoxic infarcts in the brain presents as this type of necrosis, because the brain contains little connective tissue but high amounts of digestive enzymes and lipids, and cells therefore can be readily digested by their own enzymes.[3]
  3. Caseous necrosis can be considered a combination of coagulative and liquefactive necroses,[3] typically caused by mycobacteria (e.g. tuberculosis), fungi and some foreign substances. The necrotic tissue appears as white and friable, like clumped cheese. Dead cells disintegrate but are not completely digested, leaving granular particles.[3] Microscopic examination shows amorphous granular debris enclosed within a distinctive inflammatory border.[4] Granuloma has this characteristic.[6]
  4. Fat necrosis is specialized necrosis of fat tissue,[6] resulting from the action of activated lipases on fatty tissues such as the pancreas. In the pancreas it leads to acute pancreatitis, a condition where the pancreatic enzymes leak out into the peritoneal cavity, and liquefy the membrane by splitting the triglyceride esters into fatty acids through fat saponification.[4] Calcium, magnesium or sodium may bind to these lesions to produce a chalky-white substance.[3] The calcium deposits are microscopically distinctive and may be large enough to be visible on radiographic examinations.[5] To the naked eye, calcium deposits appear as gritty white flecks.[5]
  5. Fibrinoid necrosis is a special form of necrosis usually caused by immune-mediated vascular damage. It is marked by complexes of antigen and antibodies, sometimes referred to as “immune complexes” deposited within arterial walls[4] together with fibrin.[4]

Other clinical classifications of necrosis

  1. There are also very specific forms of necrosis such as gangrene (term used in clinical practices for limbs which have suffered severe hypoxia), gummatous necrosis (due to spirochaetal infections) and hemorrhagic necrosis (due to the blockage of venous drainage of an organ or tissue).
  2. Some spider bites may lead to necrosis. In the United States, only spider bites from the brown recluse spider (genus Loxosceles) reliably progress to necrosis. In other countries, spiders of the same genus, such as the Chilean recluse in South America, are also known to cause necrosis. Claims that yellow sac spiders and hobo spiders possess necrotic venom have not been substantiated.
  3. In blind mole rats (genus Spalax), the process of necrosis replaces the role of the systematic apoptosis normally used in many organisms. Low oxygen conditions, such as those common in blind mole rats’ burrows, usually cause cells to undergo apoptosis. In adaptation to higher tendency of cell death, blind mole rats evolved a mutation in the tumor suppressor protein p53 (which is also used in humans) to prevent cells from undergoing apoptosis. Human cancer patients have similar mutations, and blind mole rats were thought to be more susceptible to cancer because their cells cannot undergo apoptosis. However, after a specific amount of time (within 3 days according to a study conducted at the University of Rochester), the cells in blind mole rats release interferon-beta (which the immune system normally uses to counter viruses) in response to over-proliferation of cells caused by the suppression of apoptosis. In this case, the interferon-beta triggers cells to undergo necrosis, and this mechanism also kills cancer cells in blind mole rats. Because of tumor suppression mechanisms such as this, blind mole rats and other spalacids are resistant to cancer.[7][8]


Necrosis may occur due to external or internal factors. External factors may involve mechanical trauma (physical damage to the body that causes cellular breakdown), damage to blood vessels (which may disrupt blood supply to associated tissue), and ischemia.[9] Thermal effects (extremely high or low temperature) can result in necrosis due to the disruption of cells. In frostbite, crystals form, increasing the pressure of remaining tissue and fluid causing the cells to burst.[9] Under extreme conditions tissues and cells die through an unregulated process of destruction of membranes and cytosol.[10]

Internal factors causing necrosis include Necrosis can be activated by components of the immune system, such as the complement system; bacterial toxins; activated natural killer cells; and peritoneal macrophages.[1] Pathogen-induced necrosis programs in cells with immunological barriers (intestinal mucosa) may alleviate invasion of pathogens through surfaces affected by inflammation.[1] Toxins and pathogens may cause necrosis; toxins such as snake venoms may inhibit enzymes and cause cell death.[9]

Activation-induced death of primary T-lymphocytes and other important constituents of the immune response are caspase-independent and necrotic by morphology; hence, current researchers have demonstrated that the occurrence of necrotic cell death can not only occur during pathological processes but also during normal processes such as tissue renewal, embryogenesis, and immune response.[9]


Until recently, necrosis was thought to be an unregulated process.[11] There are two broad pathways in which necrosis may occur in an organism.[11]

The first of these two pathways initially involves oncosis, where swelling of the cells occur.[11] The cell then proceeds to blebbing, and this is followed by pyknosis, in which nuclear shrinkage transpires.[11] In the final step of this pathway the nucleus is dissolved into the cytoplasm, which is referred to as karyolysis.[11]

The second pathway is a secondary form of necrosis that is shown to occur after apoptosis and budding.[11] Cellular changes of necrosis occur in this secondary form of apoptosis, where the nucleus breaks into fragments, which is known as karyorrhexis.[11]

Cellular changes

The nucleus changes in necrosis, and characteristics of this change are determined by manner in which its DNA breaks down:

  • Karyolysis: the chromatin of the nucleus fades due to the loss of the DNA by degradation.[4]
  • Pyknosis: the nucleus shrinks and the chromatin condenses.[4]
  • Karyorrhexis: the shrunken nucleus fragments to complete dispersal.[4]

Plasma alterations are also seen in necrosis. Plasma membranes appear discontinuous when viewed with an electron microscope. This discontinuous membrane is caused by cell blebbing and the loss of microvilli.[4]


There are many causes of necrosis, and as such treatment is based upon how the necrosis came about, treatment of necrosis typically involves two distinct processes. Usually, the underlying cause of the necrosis must be treated before the dead tissue itself can be dealt with.

  • In the case of ischemia, which includes myocardial infarction, the restriction of blood supply to tissues causes hypoxia and the creation of reactive oxygen species (ROS) that react with, and damage proteins and membranes. Antioxidant treatments can be applied to scavenge the ROS.[12]
  • Wounds caused by physical agents, including direct physical trauma and injury, can be treated with antibiotics and anti-inflammatory drugs to prevent bacterial infection and inflammation. Keeping the wound clean from infection also prevents necrosis.
  • Chemical and toxic agents (e.g. pharmaceutical drugs, acids, bases) react with the skin leading to skin loss and eventually necrosis. Treatment involves identification and discontinuation of the harmful agent, followed by treatment of the wound, including prevention of infection and possibly the use of immunosuppressive therapies such as anti-inflammatory drugs or immunosuppressants.[13] In the example of a snake bite, the use of anti-venom halts the spread of toxins whilst receiving antibiotics to impede infection.[14]

Even after the initial cause of the necrosis has been halted, the necrotic tissue will remain in the body. The body's immune response to apoptosis, which involves the automatic breaking down and recycling of cellular material, is not triggered by necrotic cell death due to the apoptotic pathway being disabled.[15] The standard therapy for necrosis is removal of the dead tissue (debridement) either by surgical or non-surgical means. Depending on the severity of the necrosis, this may range from removal of small patches of skin, to complete amputation of affected limbs or organs. Chemical removal of necrotic tissue is another option in which enzymatic debriding agents, categorised as proteolytic, fibrinolytic or collagenases, are used to target the various components of dead tissue.[16] In select cases, special maggot therapy using Lucilia sericata larvae has been employed to remove necrotic tissue and infection.[17]

In plants

If calcium is deficient, pectin cannot be synthesized, and therefore the cell walls cannot be bonded and thus an impediment of the meristems. This will lead to necrosis of stem and root tips and leaf edges.[18]

See also



1. Proskuryakov, S. Y. a., Konoplyannikov, A. G. & Gabai, V. L. Necrosis: a specific form of programmed cell death? Experimental Cell Research 283, 1-16, doi:10.1016/s0014-4827(02)00027-7 (2003).

2. Kasper D.L., Zaleznik D.F. (2001). Gas gangrene, antibiotic associated colitis, and other Clostridial infections. In Braunwald E., Kasper D.L. et al. (Eds). Harrisons’s principles of internal medicine 15th ed., pp. 922–927. McGraw Hill, New York

3. Vinay K, Abul K. A., Nelson F, Jon A. (2010) Robbins & Cotran Pathologic Basis of Disease, 8th ed., pp. 12–41. Saunders Elsevier, Philadelphia

4. Craft, J. et al. Understanding Pathophysiology. 1 edn, (Mosby Elsevier, 2011).

5. Kumar, V., Abbas, A. K., Fausto, N. & Aster, J. C. Robbins and Cotran Pathological Basis of Disease. 8 edn, (Saunders Elseveir, 2010).

6. McConnell, T. H. The Nature of Disease: Pathology for the Health Professional. (Lippincott Williams & Wilkins, 2007).

7. Stevens, A., Lowe, J. S. & Young, B. Wheater's Basic Histopathology: A Colour Atlas and Text. 4 edn, (Churchill Livingstone, 2003).

8. Nazarian, R. M., Van Cott, E. M., Zembowicz, A. & Duncan, L. M. Warfarin-induced skin necrosis. Journal of the American Academy of Dermatology 61, 325-332, doi:10.1016/j.jaad.2008.12.039 (2009).

9. Raffray, M. & Gerald M, C. Apoptosis and necrosis in toxicology: A continuum or distinct modes of cell death? Pharmacology & Therapeutics 75, 153-177, doi:10.1016/s0163-7258(97)00037-5 (1997).

10. Proskuryakov, S. Y. a., Konoplyannikov, A. G. & Gabai, V. L. Necrosis: a specific form of programmed cell death? Experimental Cell Research 283, 1-16, doi:10.1016/s0014-4827(02)00027-7 (2003).


13. Robertson, J Burke, B Caceci, T Santo, A n.d, ‘Introductory pathology lab exercises’, retrieved 9 September 2012, .

14. Eum, H.-A., Cha, Y.-N. & Lee, S.-M. Necrosis and apoptosis: Sequence of liver damage following reperfusion after 60 min ischemia in rats. Biochem. Biophys. Res. Commun. 358, 500-505, doi:10.1016/j.bbrc.2007.04.153 (2007).

15. Cooper, K. L. Skin and Wound Care. Drug Reaction, Skin Care, Skin Loss. Crit. Care Nurse 32, 52-59, doi:10.4037/ccn2012340 (2012).

16. Chotenimitkhun, R. & Rojnuckarin, P. Systemic antivenom and skin necrosis after green pit viper bites. Clinical Toxicology (15563650) 46, 122-125, doi:10.1080/15563650701266826 (2008).

17. Edinger, A. L. & Thompson, C. B. Death by design: apoptosis, necrosis and autophagy. Curr. Opin. Cell Biol. 16, 663-669, doi:10.1016/ (2004).

18. Anu, S., Ernane, D. R. & Morris, D. K. Options for nonsurgical debridment of necrotic wounds. Advances in Skin & Wound Care 14, 96-96 (2001).

19. Horobin, A. J., Shakesheff, K. M. & Pritchard, D. I. Maggots and wound healing: an investigation of the effects of secretions from Lucilia sericata larvae upon the migration of human dermal fibroblasts over a fibronectin-coated surface. Wound Repair. Regen. 13, 422-433, doi:10.1111/j.1067-1927.2005.130410.x (2005).

External links

  • Life In The Fast Lane: toxicology Conundrum #018
  • Secondary necrosis of a neutrophil
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.