Fibroadenomas usually occur in premenopausal women. They may grow during pregnancy, breastfeeding, or estrogen therapy.
Although fibroadenomas have a typical feel on physical examination and appearance on breast ultrasound, the only way to ensure a breast lump is a fibroadenoma is through a biopsy. Proven fibroadenomas may not need treatment unless they are large, fast-growing, or cause bothersome symptoms.
This article explains what you need to know about breast fibroadenomas, how they are diagnosed, and what to do about them.
Fibroadenoma Symptoms
Typically, the only symptom of a fibroadenoma is a small lump in the breast that you may discover during a self-exam. These lumps feel firm, round, smooth, rubbery, and are movable. Fibroadenomas are so mobile that women sometimes refer to them as “breast mice,” as they tend to run away from your fingers.
The masses may feel tender or painful, especially right before your period, when they may swell due to hormonal changes.
Most fibroadenomas are between 1 and 5 centimeters in diameter (0.39 inches to nearly 2 inches), but large fibroadenomas can be the size of a small lemon—about 15 centimeters (5.9 inches).
What Causes Fibroadenomas?
The exact cause of fibroadenomas is unknown. They seem to be influenced by estrogen because they appear most often in premenopausal or pregnant women, or in women who are taking estrogen therapy. Conversely, they may shrink or disappear after menopause.
Most fibroadenomas change in size during your menstrual cycle, when your hormone levels are changing. Thus, during this period, the same fibroadenoma can become more noticeable or it may shrink to the point where it is not easily detected.
Risk Factors
Fibroadenomas are most common in women who are between 15 and 30 years old and during pregnancy. Fibroadenomas occur in 10% of all women and in 20% of Black women specifically.
Once you hit menopause, your risk goes down unless you’re using estrogen therapy.
When to See a Healthcare Provider
If you notice a lump during your monthly breast exam, it’s important to see your healthcare provider even if you think it may be a fibroadenoma. Fibroadenomas tend to have features that distinguish them from malignant growths, but the only way to be certain that a lump isn’t cancerous is with a biopsy.
Your healthcare provider will also be able to identify the type of fibroadenoma you have. This is important because some fibroadenomas may slightly increase your risk of developing breast cancer. If you have this type of fibroadenoma, a healthcare provider may recommend removing it.
Diagnosis
A fibroadenoma may first be discovered on physical examination or during a routine screening mammogram. On a mammogram, fibroadenomas appear as round or oval smooth-edged masses. The outline will be clearly defined, not blurry, and will not be invading the adjacent spaces. Sometimes they are accompanied by coarse calcifications (calcium deposits). Fibroadenomas can look like cysts or a well-contained tumor.
If you notice a lump during an exam or if an abnormality is seen on mammography, a breast ultrasound is usually the next step. This is especially true if you have dense breast tissue, which can make a lump more difficult to view.
On ultrasound, a fibroadenoma will be easier to distinguish from other tissue because of the way it responds to sound waves. It will appear as a dark area with a definite outline. It will look homogeneous (looks the same throughout), round or oval, and may have smooth-edged bumps.
Your doctor may also order digital breast tomosynthesis (DBT), a specialized form of mammography that creates 3D images of the breast, and allows a more detailed evaluation when compared to a regular mammogram.
Biopsy
While imaging tests may suggest a fibroadenoma, the conclusive diagnostic test is usually a breast biopsy, a procedure to remove a sample of tissue for examination in a lab.
Different types of biopsy procedures include fine-needle aspiration or core-needle biopsy, both of which use needles to extract tissue, and open biopsy, a surgical procedure in which a cut is made in the skin to extract sample tissue. Which type your healthcare provider chooses will depend on the characteristics of the lump, its location, and other factors. In women at increased risk for breast cancer, your healthcare provider may strongly recommend surgical removal.
As with any biopsy, breast biopsies carry a risk of a false-negative result that is, the test detects no cancer when cancer is actually present). This is because a breast biopsy may only sample one part of a lump and could miss the cancerous portion. For this reason, you should continue routine breast cancer screening even if you have had a benign biopsy in the past.
Fibroadenoma Treatment
It’s important to distinguish between the two types of fibroadenomas when choosing the best treatment options because of the difference in associated breast cancer risk.
Fibroadenomas are classified as either:
Simple: Most fibroadenomas are the simple type; they are more common in younger people. There’s usually just one mass in your breast, with a definite border and very uniform cells. A simple fibroadenoma does not raise your risk for breast cancer. Complex: Complex fibroadenomas are less common but become more common as people age. While they may have a definite border, it’s what is inside this kind of fibroadenoma that makes it different. Under a microscope, a complex fibroadenoma will not look organized and uniform like a simple one. There is often evidence of rapidly dividing cells (hyperplasia) that may have an abnormal appearance (atypia). Having a complex fibroadenoma can raise your risk of developing breast cancer,
Aside from fibroadenoma type, other factors may influence treatment choice, such as:
Symptoms, especially discomfort and painEmotional state, such as undue worry about it being cancer
In considering all of this, your healthcare provider will recommend one of the following fibroadenoma treatment options.
Watch and Wait
Since fibroadenomas are not always troublesome and sometimes shrink on their own, just keeping an eye on their progress is the least invasive way to handle them.
Laser Ablation
In your surgeon’s office, an ultrasound-guided laser device is used to destroy the fibroadenoma, leaving behind only a tiny scar, no sutures, and no change in breast shape. You don’t need general anesthesia, and it’s usually an outpatient procedure, which means no hospital stay.
Cryoablation
Cryoablation is a fast, efficient way to freeze a fibroadenoma. In one office visit, the healthcare provider simply freezes the lump so that healthy tissue can take over. This procedure takes less than 30 minutes and results in a tiny scar.
Radiofrequency Ablation (RFA)
This is a way to remove fibroadenomas without resorting to a lumpectomy. Using local anesthesia and ultrasound guidance, a 6- to 8-millimeter (about 1/4 inch to nearly 1/3 inch) cut is made above the fibroadenoma. Through this cut, a surgical wand is inserted and then tipped by a knife that is heated by radiofrequency current. This helps cut through the breast tissue without causing much bleeding. Once it reaches the target, small wires and robotic arms capture the fibroadenoma and extract it.
Vacuum-Assisted Excision
Breast biopsy systems can now be used as a mostly noninvasive way to remove small fibroadenomas. In less than an hour, and under local anesthesia, a 6-millimeter (1/4 inch) cut is made over the fibroadenoma. Then, with ultrasound guidance, a probe is threaded into the lump, which vacuums out sections of the tissue. Recovery is quick and your scar will be quite small.
High-Frequency Focused Ultrasound (HFU)
This is a relatively new treatment that has been used for fibroadenomas and, sometimes, even for breast cancer. HFU appears to cause the selective destruction of deep tissues without damaging surrounding healthy tissue.
Lumpectomy
Surgical removal can be done if you’re worried about a fibroadenoma. Depending on the relative size of the lump and your breast, a lumpectomy may cause a change in your breast’s size or shape. New fibroadenomas may grow in the area of the first lump, so you should know that surgery is not a guarantee that you’ll never have another fibroadenoma. On the other hand, your fibroadenoma can be carefully examined by a pathologist to make sure your diagnosis is correct.
For pain that may be due to a fibroadenoma, over-the-counter pain medications and applied heat are often used.
Complementary and Alternative Medicine (CAM) Concerns
Certain herbal supplements and diets have been touted as effective treatments for fibroadenomas or their symptoms, but few controlled studies have looked into these remedies. Adopting a healthy lifestyle, including regular exercise and eating lots of fruits and vegetables, is always good advice and may help relieve fibroadenoma symptoms. But remember that these interventions shouldn’t replace proper testing and treatment. By self-treating, you may be risking your health.
Summary
Breast fibroadenomas are the most common type of noncancerous (benign) breast tumor. They usually occur in premenopausal women. They may be felt during your monthly breast self-exam, and they can be detected on imaging with mammography or ultrasound. The only way to be sure that a breast lump is a fibroadenoma is through a biopsy.
Most fibroadenomas are considered simple and are not associated with an increased risk of breast cancer. Some fibroadenomas are considered complex, because their cells look unusual under a microscope. Women with complex fibroadenomas have an increased risk of developing breast cancer, and they may require careful monitoring for signs of developing cancer.
Proven fibroadenomas may not need treatment unless they are large, fast growing, or cause bothersome symptoms. Although alternative and complementary therapies (like herbs and dietary changes) may help with symptoms, they should not replace standard screening and treatment.
A Word From Verywell
While having a biopsy can be unsettling, it may end up being the best way to reduce anxiety about a fibroadenoma. Most breast lumps are not cancerous, and this is the only way to conclusively determine what’s causing yours. Keep in mind that there are many types of breast lumps, only one of which is a fibroadenoma. If you detect one, don’t hesitate—get it checked out by your healthcare provider.
A subtype of fibroadenoma, called complex fibroadenoma, causes changes that are visible under a microscope. Less than half of fibroadenomas are considered complex. Patients with complex fibroadenoma have a slightly increased risk of breast cancer when compared to the general population. However, it is not clear whether the complex fibroadenoma actually causes cancer to form or whether it is just associated with cancer risk.
