What causes breast lumps and when to see a doctor

When most individuals discover a lump in their breast tissue, the biggest concern is usually that it could be breast cancer. While any breast lump should always be investigated to rule out breast cancer, there are many other more common causes of breast lumps. Here we’ll discuss what they are, including cancer, signs and symptoms to look out for, and when to seek medical help. 

Causes of breast lumps

Breast cancer

Lumps caused by breast cancer can vary in size and occur anywhere in your breast eg behind the nipple, deep within your breast, or near the surface. It may feel hard like a stone, or feel like a firm ball that you can’t compress.

Breast cancer is diagnosed with a mammogram, ultrasound scan and the collection of a tissue sample (biopsy) for testing in a lab.

Breast abscesses

These refers to pus-filled lumps that usually develop just underneath the skin causing pain and red, hot skin. A breast abscess is usually caused by a bacterial infection and is most common in breastfeeding women as a complication of mastitis (inflammation of the mammary glands).  

Fibroadenomas and adenomas

Fibroadenomas are the most common cause of breast lumps in younger women in their teens and early twenties. However, they can occur in older women up to the age of around 40. 

A fibroadenoma is caused by an overgrowth of fibrous and glandular tissue in one area of the breast due to an exaggerated response to the hormone oestrogen. Fibroadenomas are not cancerous and don’t increase your risk of cancer. 

They are very mobile, so if you push at the lump it can move away from your finger or hand. Fibroadenomas can vary in size considerably, from a few millimetres to five or more centimetres. Larger fibroadenomas can deform the breast and cause anxiety. Consequently, some women choose to have them surgically removed. 

Adenomas are similar but less common than fibroadenomas and are caused by the non-cancerous overgrowth of glandular tissue alone, without the fibrous element. 

Cysts and galactoceles

Breast cysts are among the most common non-cancerous causes of breast lumps. They are collections of fluid within the breast that commonly start to appear in women in their mid to late thirties and older as part of natural changes in their breasts with age. This is a physiological process and should not cause concern. 

Women who develop breast cysts tend to have them repeatedly. Cysts are easily treated with ultrasound-guided syringe aspiration. 

Women who are breastfeeding can develop blockages in their ducts (thin tubes that carry milk from milk-producing glands to the nipple). This can cause small milk-filled lumps called milk cysts (or galactoceles) to develop. 

Lipomas

Lipomas are lumps of fat that can develop in any part of your body that contains fat, with the exception of the palms of your hands and the soles of your feet. They’re very rarely cancerous.

As the breast contains a significant amount of fatty tissue, lipomas can form here. They do not need any treatment if they are small, but can be removed if they are very large and deform your breast. 

Fat necrosis 

Trauma to the breast tissue, such as after a fall or car crash, can cause fatty tissue in your breast to become bruised and damaged. This produces fat lumps or oil cysts in your breast that can be diagnosed with a mammogram or ultrasound scan. The lumps will disappear on their own after a few weeks. 

When to see a doctor

It is important to regularly check your breasts every month at roughly the same point in your menstrual cycle, ideally a few days after your period has finished. This is because hormonal changes during your menstrual cycle can cause changes in how your breasts feel. 

An easy way to incorporate your monthly breast check into your routine is to check your breasts when you’re in the bath or shower, or when moisturising your body. Make sure you examine all parts of your breasts ie all four quarters, including the central area behind your nipple, as well as your armpits. 

It can be more difficult to detect breast lumps if you’re a younger woman as the tissue tends to be denser and more lumpy. You should, therefore, pay attention to any changes in your breasts eg bulges, lumpiness in one area, changes in their shape, folds or dimples. 

If you detect a lump in your breasts that is not usually there or a change in the lumpiness of your breasts, see your GP. Most breast lumps are not cancerous but it is important to have them investigated to rule this out. 

Investigating breast lumps

If you detect a lump in your breast, your GP will carry out a breast lump investigation. 

This starts with taking a detailed medical history, including any medication you’re on, eg. hormone replacement therapy (HRT) can make your breasts become lumpy though this is not usually cancerous. HRT also slightly increases your risk of breast cancer the longer you’re on it — there are around five extra cases of breast cancer in every 1,000 women on combined HRT for five years. 

Your GP will also ask about your family history of breast cancer and about your symptoms eg when did you first notice the lump? Has it changed over time or with your menstrual cycle? Have you had any breast lumps in the past?

Next, they will perform a clinical examination of both of your breasts and armpits, and the areas above and below your collarbone. If they confirm that you have a lump, they will refer you to a triple assessment (or one-stop) breast clinic where you will see a breast surgeon for a full clinical assessment and a radiologist for a mammogram and/or ultrasound scan.

Depending on the results of your scan, you then may need an ultrasound-guided biopsy so that a sample of the tissue from your lump can be collected and sent to a lab for examination. 

At a one-stop breast clinic, a clinical examination of your breasts, imaging and a biopsy can be carried out during one visit. The results of your biopsy will usually take several days. 

Treating breast lumps

If your breast lump is non-cancerous (benign) you may not need any treatment unless it is causing you cosmetic concerns or significant anxiety, in which case you may be offered surgery to remove the lump. 

If you have had a breast lump before and your lump recurs, you will need to go through the same investigations as before (ie clinical examination, imaging and a biopsy, if needed).

If you have a breast cyst, this can be drained in a clinic under the guidance of imaging. Cysts can, however, refill, or new cysts may develop elsewhere in your breast. New cysts can also be drained. 

Breast cancer treatment

If your lump is diagnosed as breast cancer, your treatment will depend on the type and stage of breast cancer. This may include surgery, radiotherapy, chemotherapy, hormone-blocking treatment and/or anti-cancer targeted drug therapy. Surgery may involve removal of the lump and a rim of normal tissue around it (lumpectomy) or removal of the whole breast (mastectomy). 

If you have a lumpectomy to treat your breast cancer, the area beneath the wound site may feel hard after surgery where the internal tissue has been stitched together. This is not because any of the lump has been left behind and will disappear over a few weeks. 

In some cases, a fluid-filled lump called a seroma may develop after a lumpectomy. This will also spontaneously resolve and disappear over a few weeks. However, if the seroma becomes painful or infected, it can be drained with a needle.