Necrosis Causes and Symptoms in the Human Body

Necrosis is the death of tissues of the body. It happens when tissue isn't getting enough blood due to injury, infection, or chemical exposure. Resulting damage cannot be reversed. The term gangrene refers to a large area of necrosis.

The sole treatment for necrosis is the removal of the dead tissue.

This article discusses the types of necrosis as well as the causes and risk factors. It also covers symptoms of necrotic tissue and how it's treated.

Types of Necrosis

There are several types of necrosis, as it can affect many areas of the body, including bone, skin, organs and other tissues. Each type has distinct features.

The type of necrosis that develops depends on which tissues are necrotic and what event (such as an injury or infection) triggered it. The types include:

Coagulative Necrosis

Coagulative necrosis occurs when there is a lack of blood flow and oxygen to the affected tissues. One way this can happen is when an artery becomes blocked due to a blood clot.

Coagulative necrosis can affect any organ in the body except for the brain. The necrotic tissue becomes firm and pale in comparison to surrounding tissues.

Liquefactive Necrosis

Liquefactive necrosis happens as a result of a bacterial, viral, fungal, or parasitic infection. It can also occur in the brain due to an ischemic injury, such as a stroke that causes the death of brain tissue.

This type of necrosis is typically seen in the brain, the lungs, or the tissues surrounding a site of infection. Liquefactive necrotic tissue softens until it turns into a pus-filled abscess.

Caseous Necrosis

Caseous necrosis is another type of necrosis that typically happens as a result of a bacterial or fungal infection. The most common cause of caseous necrosis is tuberculosis—a bacterial disease that leads to caseous necrosis in the lungs.

Caseous necrotic tissue has a cheese-like appearance. The necrotic tissue becomes yellowish-white and soft with a well-defined border around the affected area.

Fat Necrosis

Fat necrosis is necrosis that occurs in parts of the body that contain a lot of fatty tissue, such as the pancreas and breast tissues.

Fat necrosis is often triggered by an event that damages the affected tissue area, such as injury, surgery, or radiation therapy.

Fat necrotic tissue is speckled with small, white chalky deposits. These white spots are formed by calcium and fatty acids that are deposited into the necrotic tissue.

Fibrinoid Necrosis

Fibrinoid necrosis is necrosis that occurs within blood vessels. It is triggered by immune reactions that damage blood vessels.

Fibrinoid necrotic tissue is usually not visible to the naked eye. When viewed under a microscope, inflammation and the buildup of a substance called fibrinoid can be seen in blood vessel walls.

Causes of Necrosis

Necrotic tissue forms when not enough blood—and the oxygen that blood carries—reaches the affected tissues.

Blood clots and blood vessel damage are just two of the many causes that can trigger necrosis. Injuries, infections, chronic diseases, and toxins that block blood flow to an area can cause necrotic tissue to form in that area.

Injury

Traumatic injuries can damage blood vessels and cut off blood flow to the surrounding bones and tissue areas. Anything from a car accident to falling from a ladder can result in a traumatic injury that triggers necrosis.

Frostbite, in which tissues are severely damaged by cold, is a common cause of necrosis. If frostbite is not treated quickly, the frostbitten area turns black and dies (gangrene). These necrotic tissues cannot be healed and are typically removed via surgical amputation.

Other injuries that can lead to necrosis include:

• Electrical burn
• Bone fracture
• Traumatic brain injury
• Chemical burn
• Radiation exposure

Infarction

Infarction is tissue death that occurs when not enough blood reaches the affected area.

Necrosis due to infarction is often the result of a blood clot, such as a deep vein thrombosis (DVT) that forms in a blood vessel and blocks blood flow to the surrounding area. If blood flow is not restored quickly, the area starves for oxygen and eventually dies.

DVT usually happens in the legs (but can happen anywhere in the body). It can result in the loss of tissue below the site of the blockage if the blood vessel is completely blocked.

Infection

A wide variety of bacterial, viral, fungal, and parasitic infections can trigger necrosis. Even a minor cut or scrape that gets infected can lead to necrosis.

Some types of infection more commonly cause necrosis than others. In particular, the bacteria called group A Streptococcus is thought to be the most common necrotizing infection.

Necrotic tissue due to infection is most often seen on the extremities, particularly the hands and feet, as well as the genitals.

Other viruses that can induce necrosis include:

• Human immunodeficiency virus (HIV)
• Herpes simplex virus type-1 (HSV-1)
• West Nile virus
• Vaccinia virus (related to smallpox)
  

Disease

Certain autoimmune diseases are known to cause necrosis, the most common of which is systemic lupus erythematosus (SLE). It's thought that people who treat their SLE with corticosteroids are most at risk, as long-term use of corticosteroids weakens bones.

A number of other diseases can trigger necrosis by damaging blood vessels and blocking blood flow to bones and tissues.

They include:

• Alcoholism
• Sickle cell disease
• Decompression disease (also called diver's disease)
• Chronic kidney failure
• Cushing's disease, in which the body makes too much of the hormone cortisol
• Gaucher disease, a genetic disorder that causes the buildup of fat cells in certain organs

Toxins

Chemical agents, such as poison, venom, and certain recreational drugs are known to trigger necrosis.

Exposure to arsenic, a metal found in rat poison and contaminated groundwater, can trigger necrosis in the kidneys. Cocaine that is laced with a white chemical called levamisole is linked to kidney necrosis as well.

Venom injected into the skin from a brown recluse spider bite can cause necrosis unless treated quickly. Bites and stings from numerous other creatures cause necrosis, including spiders, snakes, scorpions, and jellyfish.

Risk Factors

With increased age comes increased vulnerability to problems that can trigger necrosis, such as injuries and vascular disease. This makes your age one of the biggest risk factors for necrosis.

Abusing alcohol also puts you at a greater risk of developing necrotic tissue. Alcohol is cytotoxic, meaning that it is toxic to your cells. Abusing heavy amounts of alcohol over time can kill liver cells and trigger necrosis in your liver.

Having an open wound, such as an abscess or surgical incision heightens your risk of infection and therefore necrosis. Traumatic injuries and insect bites are necrosis risk factors as well.

Long-term use of corticosteroids such as prednisolone are associated with a higher risk of necrosis. Necrosis is a common complication of the autoimmune disease lupus. People who treat their lupus symptoms with corticosteroids are at an especially greater risk.

Other conditions that increase the risk of necrosis include:

• Diabetes mellitus
• Vascular disease
• Chronic renal (kidney) failure
• HIV
  

Symptoms

Symptoms of necrosis vary depending on where in your body the necrotic tissue has developed. For example, symptoms of necrosis in your kidneys include:

• Back or flank pain
• Bloody, cloudy, or dark urine
• Painful or frequent urination
• Urinating large amounts or often at night

When necrosis stems from a wound, symptoms can include:

• Pain that seems more severe than it should
• Fever (greater than 100.4°F) or chills
• Rapid heartbeat (more than 100 beats per minute)
• Numbness or pain extending past the wound
• Rapidly spreading redness from the wound
• Pain and warmth near the wound
• Skin blisters
• A crackling sensation under the skin (crepitus)
• Grayish, smelly liquid draining from the wound
• Difficulty thinking clearly
• Excessive sweating

Treatment

A complete blockage of blood flow is typically painful, and usually painful enough to make someone seek medical help immediately. 

Treatment may include surgery to restore blood flow or to remove the damaged tissues, antibiotics to prevent or treat infection, or treating the burn or other issues that caused the initial damage.

In many cases, necrosis treatment starts by identifying and addressing the cause of cell death. Restoring blood flow to the affected areas is the most important priority in order to prevent further damage.

Once the blood supply has been restored, which may require surgery, any dead tissue can be removed.