Breast Oil Cysts: Causes, Diagnosis, and Treatment

Breast oil cysts are benign (Non-cancerous) breast lump. They usually feel like lumps that are common in breast cancer. They can be diagnosed with ultrasound or other breast imaging. Oil cysts in the breast are often the result of a chest injury or medical procedure.

Cysts are the most common type of breast lump, especially in people between the ages of 35 and 50. Cysts are pouches filled with fluid, pus, air, or other substances. They have an outer wall, or barrier, that keeps the cyst’s inner contents inside the sac.

Breast oil cysts are filled with oily fluid produced by the breakdown of breast fat cells. They often feel soft and supple. They usually don’t need treatment.

Breast oil cysts are not cancerous and do not increase the risk of breast cancer. However, in rare cases, they can be associated with an underlying cancer. Any lump that can be felt or related to imaging tests should be evaluated by your healthcare team.

This article discusses the symptoms, causes, diagnosis, and treatment of oily breast cysts.

Is this breast lump benign or cancerous?


When breast oil cysts are small, they are often overlooked. As the cyst gets larger, it may be discovered during a self-exam. Cysts are sometimes found on mammograms or other imaging tests.

Some breast cysts get bigger over time. Larger cysts can be felt as soft, soft, and smooth lumps on a breast exam. They may be painful or painless. Cyst-related bruising may also occur if they occur after surgery or trauma.


Oil cysts can occur with other breast conditions after breast surgery, or they can occur spontaneously. They are called oil cysts because they contain body fat in liquid form.

how they develop

During a lumpectomy or mastectomy, the fat cells in the breast may be damaged. As fat cells break down (mammary fat necrosis), their structure changes. Damaged fat cells can form hard scar tissue or an oily fluid.

When liquid fat collects in an area, a thin layer of calcium forms a wall around it. This eggshell calcification describes the appearance of oil sacs on mammograms. Simple and complex cysts differ from oil cysts – they do not have a calcium layer. Typically, the oil sacs are usually partially or fully surrounded by calcium.

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Damage to breast fat cells can lead to two different conditions:

  • Fat necrosis: Damaged fat cells are replaced by fibrous scar tissue
  • Oil cysts: Damaged fat cells break down and leak their oily contents into walled pockets, causing cysts

risk factor

Oil cysts often appear after breast surgery. They can also occur after a breast biopsy or removal of cancer (mastectomy). Because they can appear during cancer diagnosis and treatment, some people panic when they learn they have cancer.

Fat necrosis and oil cysts may occur include:

  • Breast cancer surgery or reconstruction
  • breast trauma
  • Breast reduction surgery
  • Radiation therapy to the breast after lumpectomy
  • Breast biopsy or fine needle aspiration
  • Breast cyst aspiration
  • mastitis (breast infection)
  • Uncommon conditions, such as polyarteritis nodosa or multiple lipocystoma

Oil cysts are more common when autologous fat grafts (fat taken from other parts of the body and placed in the breast) are used after breast augmentation surgery.

In men, most breast oil cysts are associated with trauma.


If you notice a lump in your breast, your doctor may recommend further testing. Your treatment team will help determine if additional imaging is needed or if a breast biopsy should be done. Mammograms, ultrasounds, and breast MRI (magnetic resonance imaging) are all potential tests your team may recommend.


Oily cysts usually appear on mammograms as well-defined lumps that look fatty and may have eggshell calcifications. Calcification in oil cysts is different from the type of breast calcification often associated with breast cancer.

breast ultrasound

A breast ultrasound usually shows oil cysts more clearly than a mammogram. Ultrasounds use sound waves that bounce off breast tissue to create images of lumps, lumps, and cysts.

Cysts are filled with fluid, gas, or semisolid material. This causes them to appear on ultrasound as dark, smooth-edged round or oval areas. Cysts have a clear outline that distinguishes them from surrounding tissue.

Seromas (fluid-filled cysts) look identical to oil cysts on ultrasound. However, other types of breast lumps often show up on ultrasonography with different characteristics. This difference in appearance helps providers identify structures within the breast.

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Breast MRI

Sometimes, benign breast lumps look very similar to cancer on imaging tests. A radiologist will compare any relevant areas to surrounding tissue to help determine if further testing is needed.

Typically, breast MRI is used for the diagnosis and staging of breast cancer, not as a screening tool. However, your provider may recommend it to get the very detailed pictures of the interior that an MRI can produce. Oil cysts can appear on a breast MRI, but are best diagnosed using a breast ultrasound.

Differential diagnosis

Conditions that may look similar to a breast oil cyst include:

  • simple cyst
  • fat necrosis
  • Galactocele (collection of milk)
  • hematoma
  • papilloma
  • breast abscess
  • Seroma (also common after breast surgery)
  • lipoma

Rarely, a breast oil cyst can look like a disintegrating tumor (medically known as a necrotizing malignancy). On some imaging, cell death and inflammation may look similar to an oil cyst.

treatment solutions

Breast oil cysts are benign — they are not cancerous. They do not cause breast cancer or increase the risk of breast cancer. Therefore, oil cysts can be left alone. This is often referred to as “watchful waiting”. Many times, these shrink or go away on their own without treatment.

If you develop a cyst after cancer treatment or surgery to remove a lump, such as a lumpectomy, it’s important for your provider to determine what the lump might be. Your team will work to distinguish an oil cyst from a possible cancer recurrence.

If you are diagnosed with an oily breast cyst, there are several treatment options:

  • Aspiration: If your oil sac becomes physically painful or worries you, it can be drained with a small needle (aspirated).The fluid withdrawn will be evaluated in a laboratory to make sure the lump is just an oil cyst.
  • Surgery: If the oil cyst is swollen, painful, or continues to recur, your provider may recommend surgery to remove the cyst.
  • Home remedies: If your oil cyst is painful, medications such as Advil (ibuprofen) may help. You should also wear a comfortable bra or camisole. Using an ice pack can also reduce your discomfort.
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Breast oil cyst is a common benign breast disease. They most often develop after trauma or injury to the breast. Cysts can be seen on a mammogram, breast ultrasound, or MRI. Breast oil cysts can usually be treated on their own. Fluid can be aspirated to remove and confirm the diagnosis. If the cyst is large, painful, or if the diagnosis is in doubt, surgery may be performed to remove it completely.

VigorTip words

Breast oil cysts are benign, but since they often appear after breast surgery, they can cause a lot of anxiety. Although treatment is usually not required, many women and men with oil cysts of the breast feel more comfortable with suction. After aspiration, oil cysts often shrink—both the cysts and the anxiety that accompanies them.

Frequently Asked Questions

  • Are oil cysts the same as fat necrosis?

    No, oil cysts and fat necrosis are different, although they both occur when the fat cells in the breast are damaged. Oil cysts form when the contents of fat cells break down into an oily substance and collect in a small pocket. Fat necrosis occurs when thick fibrous scar tissue replaces damaged fat cells.

  • Do Breast Oil Cysts Grow Fast?

    Breast cysts can grow at different rates, so your experience will be unique. Some breast oil cysts never grow large enough to be felt during a breast exam. Other times, the growth of an oil cyst can be painful and your provider may recommend removing it.

  • How long does it take for a breast oil cyst to go away?

    Oil sacs are usually harmless.they sometimes leave on their own But that could take months to years. If your cyst is bothering you, your provider may drain or surgically remove it.

  • Will Evening Primrose Oil Reduce Breast Oil Cysts?

    If you are interested in trying evening primrose oil to reduce breast oil cysts, talk to your provider. There is no strong scientific evidence that this is an effective remedy. Your provider should discuss all of your medications and supplements with you to reduce the risk of side effects and interactions.