Fatty tissue necrosis

Definition

Adipose tissue necrosis is the loss of adipose tissue through cell death (necrosis) of adipose tissue cells (adipocytes), which can affect various organs and body parts. Necrosis means the death of cells within a living organism. In adipose tissue necrosis, fat cells die and release the stored fat, which is absorbed by surrounding connective tissue cells. By capping, cysts filled with an oily fluid, so-called oil cysts, are formed. Calcification processes within the capsule cause hard nodes to form in the tissue, which can be up to several centimeters in diameter.

Causes

There are many causes for the development of fatty tissue necrosis. The most common cause is trauma, i.e. tissue damage caused by external force (bruising). Blunt force (e.g. belt injuries caused by the impact of a car accident) directly damages the fat cells.

As a result, the fatty tissue dies necrotically and oil cysts form, which can be felt as hard nodules. In the process, blood vessels can also be severed, causing the tissue to be undersupplied and also damaged. The latter can also occur during operations and minor surgical procedures.

A further cause can be an incorrect injection of cytotoxic drugs, which damages the fatty tissue and causes it to die. In acute pancreatitis, the protein lipase enters the surrounding tissue, is activated and destroys fat cells. Lipase is an enzyme that normally enters the small intestine with the pancreas, where it breaks down dietary fats.

The pancreas can also be damaged by external violence or circulatory problems, which also causes lipase to leak out and destroy fatty tissue. In rare cases, fatty tissue necrosis can form, especially in the lower leg area, for reasons as yet unknown. The necroses become visible as reddish papules on the skin, which turn brown with time and remain without pain.

This clinical picture is known as Necrobiosis lipoidica diabeticorum, as diabetics are frequently affected. If an injection or infusion is performed incorrectly, the fluid does not enter the punctured vessel but the surrounding tissue (extravasation). This results in painful swelling and fluid accumulation at the affected area.

Such accidental extravasations are usually harmless and the fluid in the tissue is quickly absorbed and removed by the body. However, the incorrect injection of certain drugs, especially cytostatic drugs, can lead to tissue necrosis. Cytostatic drugs are toxic substances that are used in chemotherapy to treat cancer and kill tumor cells.

If the drug enters fatty tissue, the fat cells are killed and fat tissue necrosis develops. Even diabetics who require insulin often develop fatty tissue necrosis in the abdominal wall due to the frequent subcutaneous injections of insulin. Cortisone has an anti-inflammatory effect, and injections containing cortisone are therefore administered for pollen allergies, hay fever and orthopedic problems in the buttocks area, among other things.

If the cortisone is not injected deep enough into the muscle or fluid from the canaliculus runs back into the fatty tissue, the fatty tissue dissolves and dies. The necrotic fatty tissue is visible on the skin as deep dents, which can be several cm2 in size. In some cases, the tissue can renew itself and the dent disappears after a few months.

Radiation therapy is an effective method for treating cancer patients. Local radiation destroys tumor cells and thus increases the chances of cure. However, healthy fatty tissue in the vicinity of the tumor can also be broken down, causing fatty tissue necrosis and oil cysts to form in the irradiated tissue.

This is a benign finding, as the necroses have no risk of degeneration and therefore do not require treatment. After an operation, fatty tissue necroses may develop. Due to the cell death of fat cells during necrosis, oily cysts or fat-filled cavities can form, which become increasingly calcified over time.

These calcified cysts are then mostly as swelling or tumor well to feel under the skin. A breast reduction is based on a surgical procedure in which tissue is removed.The incisions made during the surgery can also lead to the loss of fat cells or necrosis of adipose tissue. Fatty tissue necrosis can be noticeable as swelling in the breast.

Occasionally the tissue around the dead cell material is inflamed, which leads to a pressure pain when palpating the affected breast area. The skin over the necrotic breast area may also be reddened and thickened. Furthermore, swelling of lymph nodes in the immediate vicinity may occur.