Fibroadenoma is the most common type of benign breast tumor, and most don’t increase your risk of breast cancer. Although women of any age can develop fibroadenomas, they usually occur in younger, premenopausal women. A fibroadenoma typically has a well-defined round or oval shape and a rubbery-feeling and is painless. When you touch it, it’s easy to move around under the skin as opposed to being stuck in one place.
The term fibroadenoma combines the words “fibroma,” meaning a tumor made up of fibrous tissue, and “adenoma,” a tumor of gland tissue. Over time, a fibroadenoma may grow in size or even shrink and disappear. The average fibroadenoma is anywhere from the size of a marble up to 2.5 centimeters (cm) in diameter. If it grows to 5 cm or larger, it’s called a giant fibroadenoma. Higher estrogen levels due to pregnancy or hormone therapy can cause a fibroadenoma to get bigger, while menopause often causes it to get smaller. A fibroadenoma is usually a single lump, although some women develop multiple fibroadenomas in one or both breasts.
If you’re under 30 and diagnosed with a fibroadenoma through ultrasound, biopsy might not be needed. Your doctor can check on it with physical exams and ultrasounds to see if it changes or grows. If you’re in your 30s or older, your doctor may recommend a needle biopsy to confirm the diagnosis. In many cases, fibroadenomas are first picked up as women start having mammograms in their 40s and often they are biopsied, notes Dr. Alan Stolier, a breast surgical oncologist at St. Charles Hospital and the Center for Restorative Breast Surgery in New Orleans.
Most fibroadenomas aren’t associated with an increase in breast cancer risk. However, there appears to be a slight increase in risk with a “complex fibroadenoma.” This is a fibroadenoma that includes one or more of the following benign elements: cysts larger than 3 millimeters; sclerosing adenosis; epithelial calcifications; or papillary apocrine change. About 15% of fibroadenomas are categorized as complex. Talk to your doctor about the specifics of your diagnosis. Still, the risk is considered to be slight.
Closely related to fibroadenomas are adenomas, well-defined tumors made up mostly of glandular tissue. These tumors are pretty rare, but they tend to affect younger women, they can develop in the breast tissue or the nipple, and sometimes they happen during or just after pregnancy.