Fibroadenomas are the most common type of breast mass. They are benign and typically affect women in their 20s and 30s but can be found at any age. Juvenile fibroadenomas are the most common type of breast lump found in girls aged 10–18.
Fibroadenomas tend to feel firm and rubbery and move easily beneath the skin. They typically do not cause pain, although larger masses can create discomfort by pressing on surrounding tissues. On imaging exams such as mammography and ultrasound, they show smooth, clear-cut borders.
In the early stages, fibroadenomas and phyllodes tumors are difficult to distinguish. The main differences are that phyllodes tumors grow more quickly, tend to appear in older women (often in their 40s), and can be malignant (although some sources report that about 90% are benign). For this reason, masses that appear to be fibroadenomas are typically biopsied to ensure the most accurate diagnosis possible.
While the cause of fibroadenomas is not entirely clear, reproductive hormones appear to play an important role in their development and growth. They are most commonly found during the childbearing years and can grow during pregnancy, hormone therapy, and use of hormone-based contraceptives as well as fluctuate in size throughout the menstrual cycle.
Treatment recommendations for fibroadenomas vary. In some cases, doctors recommend removing them, particularly if they become large. Sometimes, they are removed for excisional biopsy in the diagnosis stage. In other cases, a fibroadenoma might stop growing or even shrink on its own. In fact, it’s common for fibroadenomas to shrink after menopause with the decrease in hormones. Women can also experience multiple fibroadenomas at once, which makes removal a more complex and appearance-altering procedure. If you’re diagnosed with one or more fibroadenomas, consult with your doctor (or more than one doctor, as opinions can vary) about what, if any, treatment they recommend.
Experts offer varying opinions about whether a fibroadenoma increases the risk of developing breast cancer. The American Cancer Society states that women with simple fibroadenomas (which look the same throughout) experience 1.5 times the risk of breast cancer than women without them, and women with complex fibroadenomas (which tend to be bigger and appear in older women) are at a slightly higher risk than that.
On the other hand, some experts assert that this perceived increased risk is a result of older, less accurate diagnosis procedures, which incorrectly identified other types of masses as fibroadenomas. It’s worth noting, however, that women who develop many fibroadenomas tend to have denser breast tissue, which is associated with a higher incidence of breast cancer.
If a woman develops a fibroadenoma, it’s likely that she will develop more. It’s not uncommon for another fibroadenoma to appear after one has been removed. This is not an indication of breast cancer.
If you notice a change in your breast tissue such as a new lump, growth of an existing lump, or a change in breast shape, consult your doctor. Iowa Radiology provides a broad range of breast imaging services, including mammography, ultrasound, breast MRI, and imaging-guided biopsy. For information about mammography and follow-up procedures, access our free resources by clicking the images below.