Overview

First and foremost, necrosis means the death of body tissue. Fat necrosis is a condition where the fat tissue in your body dies as a result of an injury or trauma. This occurs when the blood supply to this tissue is disrupted, examples include blunt trauma or damage during surgery. Fat necrosis develops gradually over time and goes through different stages.

When the cells in the fat tissue start to die, changes may be noticed in the texture or appearance of your skin in that area. A lump or a hard node is often felt under your skin. The affected area may also appear red, thickened, or bruised. These changes are normal and expected, and they usually go away on their own. Your body will eventually repair the damaged tissue.

Notably, fat necrosis occurs locally and does not spread to other body parts. If you experience any disturbing symptoms or changes in your fatty areas, it's recommended to consult a healthcare professional for proper evaluation and guidance.¹

Causes of fat necrosis

Fat necrosis affects primarily the breast and pancreas. Breast fat necrosis is caused by trauma/injury to the fatty tissues or complications following breast surgery, such as a lack of oxygen supply (hypoxia).

As regards the pancreas, fat necrosis is a result of the abnormal release of pancreatic enzymes that destroys the surrounding fat tissue. In addition, fat necrosis has been associated with certain diseases that cause inflammation of the subcutaneous fat (panniculitis).

Factors that can lead to fat necrosis includes:

Breast trauma: Injuries to the breast, like those sustained from a car accident involving a seat belt.

Breast surgery: Procedures like lumpectomy, reduction mammoplasty, or breast reconstruction.

Fine needle aspiration biopsy and cytology (FNAB, FNAC): Medical procedures involving the insertion of a thin needle to collect tissue samples.

Radiotherapy: Treatment involving the use of high-energy radiation to target cancer cells.

Pancreatic disease: Conditions such as acute pancreatitis, pancreatic cancer, or pancreatic injury.

Panniculitis: Certain forms of inflammation affecting the subcutaneous fat, including subcutaneous fat necrosis of the newborn, Weber-Christian disease, and polyarteritis nodosa.

These are some of the common causes of fat necrosis, there are other less common cases.² 

Signs and symptoms of fat necrosis

Signs and symptoms of fat necrosis include:

Irregular masses under the skin: You may feel lumps or nodules that are not smooth or uniform in shape when you touch the affected area.

Tenderness: The areas where fat necrosis occurs can be sensitive or painful to touch.

Skin tethering: Fat necrosis can cause the skin to become attached or pulled inward, creating a tethered appearance.

Dimpling: The skin over the affected area may develop small depressions or puckering, resembling dimples.

Nipple retraction: In some cases, fat necrosis can lead to the retraction or inward turning of the nipple.² 

Management and treatment for fat necrosis

Treatment and management of fat necrosis can vary depending on the specific circumstances and symptoms experienced by the patient. Here are the key points in a simplified and highlighted format:

Palpable areas of fat necrosis can undergo different changes over time, including enlargement, regression, or resolution.

Surgical treatment is generally not necessary unless the fat necrosis causes pain or significant distortion in the breast shape.

Clinical follow-up is often sufficient for patients without pain or concerns about appearance.

Mammography plays a role in monitoring the condition. Lesions classified as "benign" may undergo yearly surveillance.

If a mammogram shows a finding of "most likely benign," a follow-up mammogram in 6 months may be recommended. A biopsy is the next step if malignancy is suspected.

Aspiration may be performed using a needle if the fat necrosis contains oily fluid and causes the patient discomfort.

Treatment options for solid masses or breast distortion depend on the size of the anticipated defect after excision.

Small defects may be addressed with excision alone or a combination of excision, fat grafting, and local tissue rearrangement.

Large defects, such as those resulting from partial flap loss after reconstruction, may require significant tissue debridement and reconstruction.

Additional options may include secondary free flap or tissue transfer, conversion to tissue expanders or breast implants, or contralateral symmetry procedures to achieve breast symmetry.⁴ 

Diagnosis

History and Physical:

A careful history is important to diagnose breast fat necrosis and rule out malignancy.

Trauma, breast surgery/reconstruction, breast implant removal, breast radiation, obesity, and pendulous breasts are factors to consider.

Physical Exam:

Features of breast fat necrosis include an irregular breast mass fixed to the dermis, skin tethering, and possible nipple retraction.

Evaluation:

• Thorough breast examination.
• Mammogram (+/-ultrasound, +/-MRI).
• Fine needle aspiration or core biopsy or excisional biopsy.

1. Mammographic features:

Fat necrosis can appear as a cyst or as pleomorphic microcalcifications, making it difficult to differentiate from malignancy.

2. Sonographic features:

Fat necrosis appears as a cystic lesion with internal echogenic 

bands on ultrasound.

3. Doppler ultrasound can rule out malignancy by showing no internal vascularity.

4. MRI:

MRI helps differentiate fat necrosis from carcinoma, especially in cases of pronounced fibrosis.

Fat necrosis appears as a round or oval hypointense mass on T1-weighted signal on fat saturation images.

5. Fine Needle Aspiration (FNA):

FNA is a sensitive and specific method to diagnose fat necrosis, offering an alternative to biopsy.

6. Core Biopsy:

Core biopsy is more sensitive than FNA and can be used to diagnose fat necrosis, especially in low-risk patients.

7. Excisional Biopsy:

Excisional biopsy is performed if there is a high suspicion of malignancy and core biopsy is negative.⁴ 

Complications

Complications of fat necrosis, especially related to breast fat necrosis include:

Pain: Fat necrosis can cause discomfort and pain in the affected area, which can impact the patient's quality of life.

Infection: fat necrosis may become infected in some cases, leading to additional complications and the possible need for medical intervention.

Multiple operations: Severe cases of fat necrosis may require multiple surgical procedures to address the issue and achieve the desired outcome.

Breast deformity: Fat necrosis can cause changes in breast shape or texture, leading to cosmetic concerns in females and potential deformities.

Physical and emotional impact: The patient's physical and emotional well-being can be affected following complicated fat necrosis.

No risk of malignancy: In contrast to breast cancer, fat necrosis poses little or no risk of transforming into malignancy. It is a noncancerous condition.

Also, potential complications should be discussed with patients before undergoing any surgical procedures involving fat grafting or other treatments. The provision of this information by doctors can help patients to make informed decisions and be prepared for possible outcomes.⁴

FAQs

How can I prevent fat necrosis?

1. Avoiding trauma to fatty areas of the body: Being cautious and taking steps to prevent physical injury or trauma to areas with adipose tissue can help prevent fat necrosis. This includes wearing protective clothing during activities that can cause trauma
2. A balanced and nutritious diet plays a vital role in our general health and well-being, including the health of fat (adipose) tissues. Fruits, vegetables, proteins, and whole grains can improve the function of fat cells and reduce the risk of fat necrosis
3. Medical treatments that may lead to fat necrosis should be avoided. Medical procedures, such as radiation therapy or certain surgical interventions, can increase the risk of fat necrosis. Potential risks and alternatives should be discussed with healthcare professionals before undergoing these treatments to reduce the chances of fat necrosis
4. Proper wound care and regular skin assessments: Taking care of wounds or surgical incisions properly and monitoring the skin for any changes or signs of infection can help detect and address early signs of fat necrosis. Prompt attention to wound healing can prevent complications and minimize the risk of fat necrosis.⁵ 

How common is fat necrosis?

Breast fat necrosis is not very common. It occurs in about 0.6% of cases and makes up a very small number of cases of benign lesions, about 2.75%. It is also found in about 8 in 100 cases of breast tumours and 1 to 9% of breast reduction surgeries. Middle-aged women, usually around 50 years old, and women with pendulous breasts have an increased risk of breast fat necrosis.⁴

Who is at risk of fat necrosis?

Fat necrosis can affect anyone who experiences an injury to their fatty tissue. However, certain individuals are more prone to developing fat necrosis. The following are the common risk factors for fat necrosis:

• People with breasts: Fat necrosis primarily affects breast tissue. Females with larger breast tissue have a higher likelihood of developing it
• A previous history of breast surgery is implicated, particularly procedures involving fat grafting, are known to increase the risk of fat necrosis
• Cancer patients on radiation therapy have a higher risk of developing fat necrosis in the treated area
• Fat necrosis is more common in individuals above 50 years
• Less commonly, fat necrosis can also occur in the following cases:
• Individuals who have experienced severe acute pancreatitis, a condition characterized by inflammation of the pancreas.¹
• Newborns delivered under traumatic conditions may also develop fat necrosis

While these factors increase the risk of fat necrosis, notably, not everyone with these risk factors will develop the condition.

Does fat necrosis hurt?

Fat necrosis typically does not cause pain. However, in some cases, the affected area may feel slightly tender. Pain is more commonly associated with subcutaneous fat necrosis that is accompanied by panniculitis, a condition involving chronic inflammation of the fatty tissue.¹

When should I see a doctor?

Fat necrosis is harmless most times, and treatment or follow-up may not be required. The body will naturally break down the affected tissue over time, which can take a few months. It is important to see your doctor, however, if the lump caused by fat necrosis gets bigger or if you notice any other changes in your breasts. Your doctor can evaluate the situation and provide appropriate guidance or further investigations if necessary.³

Summary

Fat necrosis is a condition where fatty tissue in the body undergoes tissue death due to injury or trauma. It commonly affects breast tissue but can also occur in other fatty areas like the abdomen, buttocks, and thighs. The main cause of fat necrosis in the breast is trauma from surgery, radiation therapy, or other injuries. It can also occur in newborns with conditions like sclerema neonatorum.

Changes in the texture or appearance of the skin, the presence of a lump or hard node under the skin, and redness or bruising in the affected area are common symptoms of presentation by affected individuals. It is true that fat necrosis is often harmless and may not require treatment. However, it is essential to consult a doctor if the lump grows bigger or if there are other changes in the breasts.

Fat necrosis is diagnosed via physical examination, ultrasound, or breast biopsy. The formation of oil cysts, calcifications, or scar tissue can complicate this medical condition. Treatment options depend on the severity of the symptoms and may include observation, pain management, or surgical removal if necessary.

Breast reconstruction is an option for individuals who have undergone mastectomy and may develop fat necrosis as a complication. It's important to consult with healthcare professionals, such as those in pediatric dermatology or the American Cancer Society, for guidance and appropriate management of fat necrosis.