Liquefactive necrosis

Liquefactive necrosis (or colliquative necrosis) is a type of necrosis which results in a transformation of the tissue into a liquid viscous mass.[1] Often it is associated with focal bacterial or fungal infections, and can also manifest as one of the symptoms of an internal chemical burn.[2] In liquefactive necrosis, the affected cell is completely digested by hydrolytic enzymes, resulting in a soft, circumscribed lesion consisting of pus and the fluid remains of necrotic tissue. Dead leukocytes will remain as a creamy yellow pus.[1] After the removal of cell debris by white blood cells, a fluid filled space is left. It is generally associated with abscess formation and is commonly found in the central nervous system.

In the brain

Due to excitotoxicity, hypoxic death of cells within the central nervous system can result in liquefactive necrosis.[1] This is a process in which lysosomes turn tissues into pus as a result of lysosomal release of digestive enzymes. Loss of tissue architecture means that the tissue can be liquefied. This process is not associated with bacterial action or infection. Ultimately, in a living patient most necrotic cells and their contents disappear.

The affected area is soft with liquefied centre containing necrotic debris. Later, a cyst wall is formed.

Microscopically, the cystic space contains necrotic cell debris and macrophages filled with phagocytosed material. The cyst wall is formed by proliferating capillaries, inflammatory cells, and gliosis (proliferating glial cells) in the case of brain and proliferating fibroblasts in the case of abscess cavities. Brain cells have a large amount of digestive enzymes (hydrolases). These enzymes cause the neural tissue to become soft and liquefy.

In the lung

Liquefactive necrosis can also occur in the lung, especially in the context of lung abscesses.[3][4]

Infection

Liquefactive necrosis can also take place due to certain infections. Neutrophils, fighting off a bacteria, will release hydrolytic enzymes which will also attack the surrounding tissues.

References

  1. ^ a b c Robbins and Cotran: Pathologic Basis of Disease, 8th Ed. 2010. Pg. 15
  2. ^ Ngan, Vanessa. "Chemical burn". DermNet New Zealand. Retrieved 4 February 2018.
  3. ^ "Cell Injury". Retrieved 2009-05-15.
  4. ^ Quaia E, Baratella E, Pizzolato R, Bussani R, Cova MA (March 2009). "Radiological-pathological correlation in intratumoural tissue components of solid lung tumours". Radiol Med. 114 (2): 173–89. doi:10.1007/s11547-008-0354-6. PMID 19082781.
Algor mortis

Algor mortis (Latin: algor—coldness; mortis—of death), the second stage of death, is the change in body temperature post mortem, until the ambient temperature is matched. This is generally a steady decline, although if the ambient temperature is above the body temperature (such as in a hot desert), the change in temperature will be positive, as the (relatively) cooler body acclimates to the warmer environment. External factors can have a significant influence.

The term was first used by Dowler in 1849. The first published measurements of the intervals of temperature after death were done by Dr John Davey in 1839.

Anemic infarct

Anemic infarcts (also called white infarcts or pale infarcts) are white or pale infarcts caused by arterial occlusions, and are usually seen in the heart, kidney and spleen. These are referred to as "white" because of the lack of hemorrhaging and limited red blood cells accumulation, (compare to Hemorrhagic infarct). The tissues most likely to be affected are solid organs which limit the amount of hemorrhage that can seep into the area of ischemic necrosis from adjoining capillary beds. The organs typically include single blood supply (no dual arterial blood supply or anastomoses). The infarct generally results grossly in a wedge shaped area of necrosis with the apex closest to the occlusion and the base at the periphery of the organ. The margins will become better defined with time with a narrow rim of congestion attributable to inflammation at the edge of the lesion. Relatively few extravasated red cells are lysed so the resulting hemosiderosis is limited and results in a progressively more pale area of infarction with time. Ischemic coagulative necrosis results and fibrosis of the affected area develops from the reparative response beginning at the preserved margins and working its way inwards. One exception to coagulative necrosis is the brain, which undergoes liquefactive necrosis in response to infarction.

Brain healing

Brain healing is the process that occurs after the brain has been damaged. If an individual survives brain damage, the brain has a remarkable ability to adapt. When cells in the brain are damaged and die, for instance by stroke, there will be no repair or scar formation for those cells. The brain tissue will undergo liquefactive necrosis, and a rim of gliosis will form around the damaged area.

Caseous necrosis

Caseous necrosis is a form of cell death in which the tissue maintains a cheese-like appearance. The dead tissue appears as a soft and white proteinaceous dead cell mass.

Coagulative necrosis

Coagulative necrosis is a type of accidental cell death typically caused by ischemia or infarction. In coagulative necrosis the architecture of dead tissue is preserved for at least a couple of days. It is believed that the injury denatures structural proteins as well as lysosomal enzymes thus blocking the proteolysis of the damaged cells. The lack of lysosomal enzymes allows it to maintain a "coagulated" morphology for some time. Like most types of necrosis if enough viable cells are present around the affected area regeneration will usually occur.

Coagulative necrosis can also be induced by high local temperature; it is a desired effect of treatments such as high intensity focused ultrasound applied to cancerous cells.

Dead on arrival

Dead on arrival (DOA), also dead in the field and brought in dead (BID), indicates that a patient was found to be already clinically dead upon the arrival of professional medical assistance, often in the form of first responders such as emergency medical technicians, paramedics, or police.

In some jurisdictions, first responders must consult verbally with a physician before officially pronouncing a patient deceased, but once cardiopulmonary resuscitation is initiated, it must be continued until a physician can pronounce the patient dead.

Death messenger

Death messengers, in former times, were those who were dispatched to spread the news that an inhabitant of their city or village had died. They were to wear unadorned black and go door to door with the message, "You are asked to attend the funeral of the departed __________ at (time, date, and place)." This was all they were allowed to say, and were to move on to the next house immediately after uttering the announcement. This tradition persisted in some areas to as late as the mid-19th century.

Death rattle

Terminal respiratory secretions (or simply terminal secretions), known colloquially as a death rattle, are sounds often produced by someone who is near death as a result of fluids such as saliva and bronchial secretions accumulating in the throat and upper chest. Those who are dying may lose their ability to swallow and may have increased production of bronchial secretions, resulting in such an accumulation. Usually, two or three days earlier, the symptoms of approaching death can be observed as saliva accumulates in the throat, making it very difficult to take even a spoonful of water. Related symptoms can include shortness of breath and rapid chest movement. While death rattle is a strong indication that someone is near death, it can also be produced by other problems that cause interference with the swallowing reflex, such as brain injuries.It is sometimes misinterpreted as the sound of the person choking to death, or alternatively, that they are gargling.

Dignified death

Dignified death is a somewhat elusive concept often related to suicide. One factor that has been cited as a core component of dignified death is maintaining a sense of control. Another view is that a truly dignified death is an extension of a dignified life. There is some concern that assisted suicide does not guarantee a dignified death, since some patients may experience complications such as nausea and vomiting. There is some concern that age discrimination denies the elderly a dignified death.

Dysthanasia

In medicine, dysthanasia means "bad death" and is considered a common fault of modern medicine.Dysthanasia occurs when a person who is dying has their biological life extended through technological means without regard to the person's quality of life. Technologies such as an implantable cardioverter defibrillator, artificial ventilation, ventricular assist devices, and extracorporeal membrane oxygenation can extend the dying process.

Dysthanasia is a term generally used when a person is seen to be kept alive artificially in a condition where, otherwise, they cannot survive; sometimes for some sort of ulterior motive. The term was used frequently in the investigation into the death of Formula One driver Ayrton Senna in 1994.

Dystrophic calcification

Dystrophic calcification (DC) is the calcification occurring in degenerated or necrotic tissue, as in hyalinized scars, degenerated foci in leiomyomas, and caseous nodules. This occurs as a reaction to tissue damage, including as a consequence of medical device implantation. Dystrophic calcification can occur even if the amount of calcium in the blood is not elevated. (A systemic mineral imbalance would elevate calcium levels in the blood and all tissues and cause metastatic calcification.) Basophilic calcium salt deposits aggregate, first in the mitochondria, and progressively throughout the cell. These calcifications are an indication of previous microscopic cell injury. It occurs in areas of cell necrosis in which activated phosphatases bind calcium ions to phospholipids in the membrane.

Calcification can occur in dead or degenerated tissue.

Fat necrosis

Fat necrosis is a form of necrosis characterized by the action upon fat by digestive enzymes.In fat necrosis the enzyme lipase releases fatty acids from triglycerides. The fatty acids then complex with calcium to form soaps. These soaps appear as white chalky deposits.It is usually associated with trauma of the pancreas or acute pancreatitis.It can also occur in the breast, the salivary glands and neonates after a traumatic delivery.

Lazarus sign

The Lazarus sign or Lazarus reflex is a reflex movement in brain-dead or brainstem failure patients, which causes them to briefly raise their arms and drop them crossed on their chests (in a position similar to some Egyptian mummies). The phenomenon is named after the Biblical figure Lazarus of Bethany, whom Jesus raised from the dead in the Gospel of John.

Liquefaction

In materials science, liquefaction is a process that generates a liquid from a solid or a gas or that generates a non-liquid phase which behaves in accordance with fluid dynamics.

It occurs both naturally and artificially. As an example of the latter, a "major commercial application of liquefaction is the liquefaction of air to allow separation of the constituents, such as oxygen, nitrogen, and the noble gases." Another is the conversion of solid coal into a liquid form usable as a substitute for liquid fuels.

Lung abscess

Lung abscess is a type of liquefactive necrosis of the lung tissue and formation of cavities (more than 2 cm) containing necrotic debris or fluid caused by microbial infection.

This pus-filled cavity is often caused by aspiration, which may occur during anesthesia, sedation, or unconsciousness from injury. Alcoholism is the most common condition predisposing to lung abscesses.

Lung abscess is considered primary (60%) when it results from existing lung parenchymal process and is termed secondary when it complicates another process e.g. vascular emboli or follows rupture of extrapulmonary abscess into lung.

Megadeath

Megadeath (or megacorpse) is one million human deaths, usually caused by a nuclear explosion. The term was used by scientists and thinkers who strategized likely outcomes of all-out nuclear warfare.

Necronym

A necronym (from the Greek words νεκρός, nekros, "dead" and ὄνομα ónoma, "name") is a reference to, or name of, a person who has died. Many cultures have taboos and traditions associated with referring to such a person. These vary from the extreme of never again speaking the person's real name, often using some circumlocution instead, to the opposite extreme of commemorating it incessantly by naming other things or people after the deceased.

For instance, in some cultures it is common for a newborn child to receive the name (a necronym) of a relative who has recently died, while in others to reuse such a name would be considered extremely inappropriate or even forbidden. While this varies from culture to culture, the use of necronyms is quite common.

Necrosis

Necrosis (from the Greek νέκρωσις "death, the stage of dying, the act of killing" from νεκρός "dead") is a form of cell injury which results in the premature death of cells in living tissue by autolysis.Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma which 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.Cellular death due to necrosis does not follow the apoptotic signal transduction pathway, but rather various receptors are activated, and result in the loss of cell membrane integrity and an uncontrolled release of products of cell death into the extracellular space.This initiates in the surrounding tissue an inflammatory response which attracts leukocytes and nearby phagocytes which eliminate the dead cells by phagocytosis. However, microbial damaging substances released by leukocytes would create collateral damage to surrounding tissues. This excess collateral damage inhibits the healing process. Thus, 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. For this reason, it is often necessary to remove necrotic tissue surgically, a procedure known as debridement.

Pallor mortis

Pallor mortis (Latin: pallor "paleness", mortis "of death"), the first stage of death, is an after-death paleness that occurs in those with light/white skin.

Principles of pathology
Anatomical pathology
Clinical pathology

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