A breast lesion is an abnormal growth or mass in breast tissue. They are usually benign. However, in some cases, a breast lesion may be cancerous or increase the risk of breast cancer.

The American Cancer Society notes that most breast changes are benign. Although, some may be cancerous or increase the risk of breast cancer.

Breast lesions may occur due to hormonal changes or as a result of surgery or injury to the breast tissue. People may feel a lump under the skin or notice other breast changes, such as tenderness or nipple discharge.

This article looks at the types of breast lesions and whether they are benign or cancerous. It also discusses symptoms, diagnosis, treatment, and when to contact a doctor.

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Types of breast lesions include:

  • Cysts: Cysts are fluid-filled sacs. People may feel a round, tender lump that is moveable. Cysts most commonly occur in females in their 30s–40s but can occur at any age.
  • Hyperplasia: Hyperplasia is an overgrowth of cells in the glands or ducts of the breast. People may not be able to feel a lump with hyperplasia, but it may show on a mammogram.
  • Lobular carcinoma in situ (LCIS): LCIS is a growth of cells in the lining of the milk glands in the breast. People will not usually be able to feel a lump with LCIS. Doctors typically diagnose these lesions using a biopsy.
  • Adenosis: Adenosis is an enlargement of the lobules, which are the milk-producing glands. There are also more glands than usual. Adenosis is a benign condition. People may feel a lump with adenosis.
  • Sclerosing adenosis: This is a type of adenosis with enlarged lobules and scar-like tissue, which may feel painful.
  • Fibroadenomas: Fibroadenomas are a common, benign breast lesion. They are movable and may feel marble-like. Fibroadenomas are typically not tender to the touch.
  • Phyllodes tumors: Phyllodes tumors are rare tumors that form in the connective tissue of the breast. Most are benign, but some may be cancerous. People may feel a firm lump in the breast, which is usually painless.
  • Intraductal papillomas: Intraductal papillomas are benign tumors in the milk ducts. People may feel a lump by the nipple and have clear or bloody nipple discharge.
  • Fat necrosis: Fat necrosis is a benign condition that may occur if there is damage to fatty breast tissue. People may feel a lump, which is usually painless.
  • Radial scars: Radial scars are lesions that appear similar to scars underneath a microscope. They may slightly increase the risk of breast cancer.

What is the most common breast lesion?

According to a 2023 study, fibroadenomas are the most common type of benign breast lesion in women.

A 2022 overview of research states that the vast majority of breast lumps and masses are benign. They are most common in females ages 30–50 years with the risk of cancerous lesions peaking postmenopause.

Some benign breast lesions may increase the risk of developing breast cancer. For example:

Radial scars may also slightly increase the risk of breast cancer.

Breast lesions can develop as a result of hormonal changes. For example, pregnancy, estrogen therapy, or perimenopause may cause fibroadenomas to form. The menstrual cycle may also affect the growth of cysts.

Injury to breast tissue, breast surgery, or radiation treatment may cause breast changes, such as fat necrosis.

Breast lesions may appear as a lump under the skin. People may also first become aware of them through screenings or tests. Benign and cancerous lesions may have similar symptoms.

Symptoms of breast lesions may include:

  • pain, tenderness, or swelling in the breast
  • a lump people can feel through the skin
  • irritation of the skin
  • scaling of the skin of the breast or nipple
  • inward turning nipple or nipple pain
  • nipple discharge

To diagnose a breast lesion, a doctor may carry out the following:

  • a physical exam of the breasts to feel for any lumps and examine any unusual changes
  • a medical history, including any risk factors for breast cancer
  • imaging tests to examine breast tissue, such as X-ray, ultrasound, or MRI scan
  • a nipple discharge analysis, which takes a sample of any nipple discharge to check for abnormalities
  • a biopsy, which takes a tissue sample to examine under a microscope for any abnormal cell changes

These tests can help a doctor identify the type of breast lesion. They can also help them determine if the legion is benign or has any risk of cancer.

Treatment can depend on the type of breast lesion a person has.

People with a benign breast lesion may not require any treatment. Instead, a doctor may recommend routine follow-ups to monitor for changes over the following 1–2 years.

Age and risk factors for breast cancer may also affect the course of treatment.

If abnormal cells are present or there is a risk a lesion may be cancerous, people may have a biopsy or surgery to remove the lesion.

If a person has any signs of a breast lesion, they will need to contact a doctor.

Most breast changes are benign. However, it is important to check for any risk of cancerous changes or underlying conditions.

In many cases, breast lesions are benign. If abnormal cells are present, people may need treatment to remove the mass.

If people have any symptoms of a breast lesion, they will need to contact a doctor to find out the underlying cause.