A breast rash can happen for many reasons. If a rash occurs with swelling, a thickening of the skin, and other symptoms, it may be a sign of breast cancer.

For this reason, a person should seek medical advice for any persistent rash on the breast. If a doctor believes there is a risk of breast cancer, they will recommend tests to gather more information.

This article explains when a rash could be cancerous and what else can cause a breast rash.

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Sergey Filimonov/Stocksy

Most breast rashes are not related to cancer. However, because they can be a sign of cancer, it is best to seek medical advice if a rash or skin change occurs on the breast. Early detection increases the chances of successful treatment if cancer is present.

Inflammatory breast cancer

Inflammatory breast cancer (IBC) is a rare form of breast cancer that can develop quickly and tends to be aggressive. Its symptoms can resemble a rash or skin irritation.

They may include:

  • breast swelling
  • thickening of the skin on the breast
  • small ridges or indents that look like orange peel
  • changes in skin color
  • pain, tenderness, or itching
  • a feeling of warmth or heaviness in one breast
  • nipple changes, such as inversion, flattening, or dimpling

IBC accounts for 1–5% of all breast cancers in the United States, according to the National Cancer Institute.

In people with IBC, the cancer cells block lymph vessels, causing inflammation of the skin. There may be no lump, and cancer may not show up on a mammogram.

IBC usually has no noticeable symptoms until skin changes become noticeable. Once this happens, prompt treatment is needed. Experts consider IBC at least a stage 3 cancer at diagnosis. It may also be stage 4, having metastasized to another place in the body.

Common forms of treatment include:

A doctor will advise people on the most suitable treatment plan.

Paget’s disease of the breast

Paget’s disease of the breast is a type of cancer that affects the skin on the nipple and usually the skin around the nipple, known as the areola.

A diagnosis of Paget’s disease can mean there is a tumor inside the breast. Often, people with Paget’s disease have invasive breast cancer.

Symptoms of Paget’s disease include:

  • itching or tingling of the nipple or areola
  • skin changes on or around the nipple, such as inflammation, crusting, flaking, or thickening
  • flattening of the nipple
  • yellow or bloody discharge from the nipple

Treatment for Paget’s disease depends upon the location of tumors in the breast. Possible treatments include:

  • surgery to remove the breast and possibly lymph nodes
  • surgery to remove the nipple and areola only
  • chemotherapy or hormonal treatments
  • radiation to treat any other tumors

Like IBC, Paget’s disease is rare. According to the National Cancer Institute, it occurs in 1–4% of all breast cancer cases.

Breast cancer treatment and rashes

People who are having treatment for breast cancer may develop rashes as a result of their treatment. Some forms of breast cancer medication, chemotherapy, hormone therapy, and radiation can cause rashes, but they are unlikely to affect only the breast.

Before starting any treatment, a person should talk with a doctor about possible side effects, including breast rashes.

The skin on the breast is prone to many common and relatively harmless rashes. Some common, noncancerous causes of rashes on the breast and other areas of the body include:

Infection

When skin rubs against skin, particularly if moisture is present, a condition called intertrigo can occur. Intertrigo is a type of bacterial or fungal infection that occurs in skin folds and can cause under-breast soreness.

Other symptoms of intertrigo include:

  • changes in skin color
  • inflammation and swelling
  • itching
  • cracked or broken skin
  • discharge, which may have an odor
  • sores or blisters

Fungal infections need medical attention, but they are not related to breast cancer.

Learn more about how fungal infections can affect the breast.

Allergic reactions

When an allergen or irritant touches the skin, an allergic reaction can lead to dermatitis, hives, and swelling.

Possible causes include:

  • new fragrances, cosmetics, and lotions
  • laundry detergents
  • insect bites or stings
  • some fabrics
  • wound dressings

Most reactions will disappear when a person stops using the product or item.

However, if severe swelling or breathing difficulty occurs, the person should seek medical help immediately. A severe reaction is known as anaphylaxis and can be life threatening.

What are some other causes of itchy skin?

Shingles

Shingles, also known as herpes zoster, can appear several years after having chickenpox. A shingles rash can be painful and may cause a single stripe of blisters on the body. Shingles does not only occur in the breast area, but it can appear there.

Shingles results from exposure to the varicella-zoster virus. According to the Centers for Disease Control and Prevention (CDC), shingles cannot pass from one person to another, and a person cannot pass it on through breast milk. However, if a lesion occurs near the areola, the person should stop breastfeeding to prevent further complications.

Breast abscess

A breast abscess is a sign of a bacterial infection. Abscesses can develop any time the skin around the nipples becomes cracked or broken. Most cases result from breastfeeding, but an abscess can also indicate diabetes or IBC.

Symptoms include:

  • breast pain
  • skin changes
  • swelling
  • discharge
  • warmth in the breast
  • flu-like symptoms, such as fever, in some cases

Treatment is necessary and usually includes draining the abscess and antibiotics. A doctor may also carry out tests to rule out breast cancer and diabetes.

Mastitis

Mastitis is an inflammation of breast tissue with several different types:

  • Lactational mastitis occurs during breastfeeding and is the most common type of mastitis.
  • Periductal mastitis is a benign inflammatory condition that usually affects females in their reproductive years.
  • Idiopathic granulomatous mastitis is a rare condition most likely to occur within 5 years of giving birth.

Mastitis symptoms include:

In some cases, there may also be:

  • an inverted or retracted nipple
  • nipple discharge
  • skin thickening
  • an abscess or ulceration
  • changes in the lymph nodes under the arm

Anyone with symptoms of mastitis should seek treatment to prevent complications. In some cases, a doctor may also wish to rule out cancer and other more serious conditions with similar symptoms.

Mammary duct ectasia

In people with mammary duct ectasia, the milk ducts lose elasticity and become wider or twisted. It usually occurs around menopause but can appear at other times.

The condition affects the area around the nipple and areola. It often has no symptoms but can cause:

  • pain and tenderness
  • discharge, which may be white, green-black, or grey
  • an inverted nipple
  • a breast lump

Often no treatment is necessary, but a doctor may prescribe antibiotics if an infection is present. They may also carry out tests to rule out other conditions, such as breast cancer.

According to the American Cancer Society, mammary duct ectasia does not increase the risk of breast cancer.

Chronic skin conditions

Skin conditions such as eczema, seborrheic dermatitis, and psoriasis can lead to skin symptoms such as changes in color, itching, and scaling. These are unlikely to affect the breasts alone.

In most cases, a breast rash is not a sign of breast cancer. However, some common breast conditions have symptoms similar to IBC and other types of breast cancer.

Some conditions, such as mastitis, may need treatment to prevent complications such as an infection.

For this reason, it is best to seek medical advice if breast changes occur, especially if they are new and have no obvious cause.

Alongside any medical treatment, the following can help reduce discomfort with a rash:

  • wearing loose clothes
  • using a mild scent-free soap
  • patting yourself dry after bathing and avoid rubbing the skin
  • avoiding sun exposure to the affected area
  • avoiding perfumes, deodorants, and other products that could aggravate the rash
  • avoiding scratching
  • asking a doctor or pharmacist about products to relieve pain and itching
  • seeking medical advice for an unfamiliar rash

A breast rash can be a sign of IBC or Paget’s disease, but most breast rashes are not malignant. Other causes of a rash include an allergy or infection.

It is best to seek medical advice for a breast rash or other breast changes, as treatment may be necessary. A doctor may also wish to rule out breast cancer as a precaution.

Read this article in Spanish.