Necrosis is the medical term for the death of cells and tissues in a living organism caused by an external, damaging factor. It is an uncontrolled and messy process that triggers a significant inflammatory response from the body’s immune system.

Necrosis vs. Apoptosis: A Critical Distinction

To understand necrosis, it is important to distinguish it from the body’s normal process of cell death, called apoptosis.

• A helpful analogy is to think of the cells in your body as individual houses in a large city.
• Apoptosis is like a planned, orderly demolition. When a house becomes old or is no longer needed, a specialized crew comes in. The contents are carefully packed up and removed, and the house is dismantled piece by piece without disturbing the neighbors. The process is quiet, clean, and contained. This is “programmed cell suicide.”
• Necrosis, however, is like a house suddenly exploding from an external event, like a gas leak. The walls burst, the cell’s contents are spewed out into the street, and the explosion causes chaos, damage, and a massive inflammatory response from the city’s “emergency services.” This messy, traumatic “cell murder” is necrosis.

Types of Necrosis

When a pathologist looks at necrotic tissue under a microscope, they can see different patterns of cell death, which provide clues to the underlying cause.

• Coagulative Necrosis: The dead tissue remains firm for a time. This is the classic pattern seen when tissue dies from a lack of blood flow (ischemia), such as in a heart attack.
• Liquefactive Necrosis: The dead tissue is digested by enzymes into a liquid, viscous mass. This is characteristic of bacterial infections that form pus, and it is the typical pattern of cell death seen in the brain after a stroke.
• Caseous Necrosis: The dead tissue has a soft, white, “cheesy” appearance. This pattern is a hallmark of infection with tuberculosis.
• Fat Necrosis: This occurs when there is damage to fatty tissue, most classically seen in acute pancreatitis.
• Gangrenous Necrosis: This is a clinical term, not a distinct cellular pattern. It refers to the necrosis of a limb, which can be “dry” (from ischemia) or “wet” (if a bacterial infection is also present).

In my experience, patients are often shocked by how quickly tissue damage can escalate, what starts as minor injury or infection may rapidly progress to visible necrosis if not treated promptly.

The cause of necrosis is always an injury or a disease process that is so severe that the cells cannot adapt or survive. The primary drivers of necrosis can be grouped into several major categories.

1. Ischemia (Lack of Blood Flow)

This is the most common cause of coagulative necrosis. When the blood supply to a tissue is cut off, the cells are deprived of the oxygen and nutrients they need to live, and they begin to die. This is the underlying cause of many of the most common and serious medical conditions:

• Myocardial Infarction (Heart Attack): A blockage in a coronary artery causes the death of heart muscle tissue.
• Cerebral Infarction (Ischemic Stroke): A blockage in an artery supplying the brain causes the death of brain tissue.
• Peripheral Artery Disease: Severe narrowing of the arteries in the legs can lead to tissue death and dry gangrene in the feet and toes.

2. Infections

• Bacterial Toxins: Some bacteria produce powerful toxins that directly kill cells and destroy tissue. A classic example is Clostridium perfringens, the bacterium that causes gas gangrene.
• Inflammatory Response: The body’s own intense inflammatory response to a severe infection can cause significant “collateral damage,” leading to the destruction of healthy tissue alongside the invading pathogens.

3. Toxins and Chemicals

Direct exposure to certain poisons, strong acids or bases, or snake and spider venoms can cause rapid chemical destruction of cells.

4. Physical and Thermal Trauma

• Severe Physical Injury: A crush injury can directly destroy cells and their blood supply.
• Thermal Injury: Extreme temperatures, such as in a full-thickness burn or severe frostbite, can cause widespread cell death.

In my experience, factors like uncontrolled diabetes, vascular disease, and certain medications (e.g., chemotherapy or anticoagulants) can significantly increase necrosis risk.

A person develops necrosis as a consequence of an underlying injury or disease. You do not “get” necrosis directly. The risk factors for developing necrosis are the risk factors for these root causes.

You are at a higher risk of developing a condition that leads to necrosis if you have:

• Risk factors for cardiovascular disease, such as high blood pressure, high cholesterol, diabetes, and a history of smoking (increasing your risk of heart attack and stroke).
• Poorly controlled diabetes, which can lead to diabetic foot ulcers and peripheral artery disease.
• A condition that weakens your immune system, increasing your risk of severe infections.
• A lifestyle or occupation that puts you at risk for severe burns or trauma.

Clinically, I also see necrosis develop as a complication of chronic conditions like pressure ulcers in bed-bound patients or necrosis around tumors undergoing rapid treatment.

The signs and symptoms of necrosis depend entirely on the organ or tissue that is affected.

Symptoms of Necrosis in the Skin and Limbs (Gangrene)

When necrosis affects a limb, a pressure ulcer, or another area of skin, the signs can be visible.

• A distinct change in skin color, which may become very pale, then reddish-purple, and finally turn a characteristic leathery black.
• A clear line of demarcation between the dead tissue and the surrounding healthy tissue.
• Numbness or a complete loss of sensation in the affected area, as the nerve endings have been destroyed.
• The area may be cold to the touch due to a lack of blood flow.
• If the dead tissue becomes infected (wet gangrene), there will be swelling, blistering, and a foul-smelling discharge.

Symptoms of Internal Necrosis

When necrosis affects an internal organ, the symptoms are those of that organ failing.

• In a heart attack: Severe chest pain, shortness of breath, sweating.
• In a stroke: Sudden one-sided weakness, difficulty speaking, loss of vision.
• In acute pancreatitis: Severe, deep abdominal pain that radiates to the back.

Any time there is a significant area of necrotic tissue in the body, it will trigger a major systemic inflammatory response, which can cause fever, chills, a rapid heart rate, and a general feeling of being very ill.

Clinically, I look for blackened or purplish skin, loss of sensation, and tissue breakdown. Early signs include swelling, warmth, and erythema before overt necrosis appears.

The diagnosis of necrosis is often suspected based on the clinical situation and is confirmed with imaging or a tissue sample.

• Visual and Clinical Diagnosis: Necrosis of the skin, such as in a gangrenous toe or a severe pressure ulcer with an eschar, is diagnosed by visual inspection. Internal necrosis is suspected based on the signs and symptoms of organ failure.
• Imaging Studies:
  • CT scans and MRI scans are essential for visualizing areas of dead tissue within internal organs. In the brain, an MRI can clearly show the area of a stroke. In the abdomen, a CT scan can show areas of necrotizing pancreatitis.
  • An angiogram may be performed to look for a blocked blood vessel that is causing the ischemia.
• Blood Tests: Blood tests can show signs of severe inflammation (a high white blood cell count and high CRP). They can also detect the release of specific enzymes from dead cells of a particular organ. For example, high levels of troponin in the blood are a sign of heart muscle necrosis (a heart attack).
• Biopsy: The definitive diagnosis of necrosis is made by a pathologist. A small sample of the affected tissue can be taken (a biopsy) and examined under a microscope. The pathologist can see the characteristic changes of dead and dying cells, confirming the diagnosis and sometimes helping to identify the cause (e.g., seeing bacteria or signs of vasculitis).

In my experience, wound cultures, labs (like elevated WBCs or lactate), and sometimes biopsy are necessary to guide treatment and rule out deeper infections.

It is crucial to understand that necrotic tissue is dead and cannot be revived. The goals of treatment are to treat the underlying cause to prevent further tissue death, to remove the dead tissue, and to support the body as it heals.

1. Treating the Underlying Cause

This is the first and most important priority.

• For Ischemia: The focus is on restoring blood flow as quickly as possible. This can involve giving clot-busting medications for a stroke or performing an angioplasty and stenting for a heart attack.
• For Infection: Aggressive treatment with intravenous (IV) antibiotics is essential to control the infection and prevent it from spreading.

2. Debridement and Surgery

The surgical removal of dead, necrotic tissue (debridement) is a cornerstone of treatment.

• Dead tissue provides a perfect breeding ground for bacteria and prevents the formation of new, healthy tissue. It must be removed to allow a wound to heal and to control an infection.
• Amputation: In cases of severe, extensive gangrene of a limb (like a diabetic foot), an amputation may be necessary to remove the dead and infected tissue and to save the patient’s life.

3. Supportive Care

• Wound Care: For necrotic skin ulcers, specialized wound care with appropriate dressings is needed to promote healing after debridement.
• Hyperbaric Oxygen Therapy: In some specific cases, such as for gas gangrene or certain non-healing wounds, breathing 100% oxygen in a pressurized chamber can help to fight certain types of bacteria and promote healing.
• Nutritional Support to provide the body with the building blocks it needs to heal.

Clinically, I’ve found that early intervention is key especially in necrotizing infections, delays can result in limb loss or systemic organ failure.

Necrosis is the traumatic death of cells and tissues, a final common pathway for a wide range of serious injuries and diseases. It is not a disease itself, but rather the visible result of a catastrophic event like a loss of blood supply or a severe infection. While dead tissue cannot be brought back to life, the progression of necrosis can often be halted. The key to a better outcome lies in the prompt and aggressive treatment of its underlying causes. Seeking immediate emergency care for the symptoms of a heart attack or a stroke, diligently managing chronic conditions like diabetes to prevent vascular disease, and getting prompt treatment for severe infections are the most effective ways to prevent widespread tissue death and its devastating consequences.

The National Institutes of Health, National Cancer Institute (NCI). (n.d.). NCI Dictionary of Cancer Terms – Necrosis. Retrieved from https://www.cancer.gov/publications/dictionaries/cancer-terms/def/necrosis

The Merck Manual Professional Version. (2023). Cellular Injury. Retrieved from https://www.merckmanuals.com/professional/special-subjects/general-pathology/cellular-injury

Robbins, S. L., Cotran, R. S., & Kumar, V. (2021). Robbins and Cotran Pathologic Basis of Disease. (Note: Citing a major pathology textbook as a general source for a fundamental concept like necrosis).