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Topics in breast health: breast anatomy breast cysts breastfeeding breast lumps breast pain (mastalgia) breast infection & inflammation (mastitis) fibroadenoma fibrocystic breast disease inverted nipples nipple discharge mammography


Fibroadenoma is a smooth, rubbery or hard lump that moves easily within the breast tissue. It is most often found in teenagers and younger women and African American women. A Fibroadenoma is typically not cancerous. Fibroadenomas are solid, smooth, firm, benign lumps that are most commonly found in women in their late teens and early 20s. They are the most common benign lumps that occur in women and can occur in women of any age. Increasingly, they are being seen in postmenopausal women who are taking hormone replacement therapy. The painless lump feels rubbery and moves around freely and very often is found by the woman herself. They vary in size and can grow anywhere in the breast tissue.

While most physicians can recognize this type of lump simply by feeling it, generally, the diagnosis is confirmed by mammography or ultrasound and fine-needle aspiration. Sometimes, in very young women, the fibroadenoma is not removed. However, since sometimes these tumors enlarge with pregnancy and breastfeeding, physicians may recommend surgically removing the fibroadenoma. A fibroadenoma is not cancer and does not lead to cancer, but sometimes an office exam, mammography and doctor cannot distinguish between a fibroadenoma or a cancer and therefore some type of breast biopsy is indicated.

The term “breast mouse” is also used to refer to a fibroadenoma. We do not know the cause of fibroadenomas; however, they are not cancer and rarely change into breast cancer. Fibroadenomas are more common in younger women and may become tender in the days before a period or grow bigger during pregnancy. Women have a choice about whether to have their fibroadenoma removed, but if it is monitored and continues to enlarge, it should be removed. Most often, younger women or those with smaller fibroadenomas will not have them taken out. The operation to remove a fibroadenoma is relatively simple. A general anaesthetic is usually required.

Juvenile fibroadenoma refers to a pattern of fibroadenoma seen predominantly in patients less than 20 years of age, although it may present in patients in their fourth decade of life. The tumour has a much more cellular stroma than the usual fibroadenoma, and the ductal component most often has a pericanalicular pattern. In some of these tumours the ductal component manifests intraductal epithelial hyperplasia, although the proliferation lacks changes suggestive of ductal carcinoma in situ. Giant fibroadenoma is a term referring to a fibroadenoma of large size, usually more than 68 cm in diameter. The size may be the result of stromal proliferation or may be due to increased connective tissue mucin. It should be distinguished from cystosarcoma phyllodes, as it lacks the character of stromal proliferation possessed by the latter tumour. Lactating fibroadenomas (also called lactating adenomas) occur during pregnancy, are often rapidly growing with histological signs of secretory activity.

On mammography, fibroadenomas are well circumscribed, oval or lobulated tumours; infrequently the border is ill defined. Calcifications are common, especially in postmenopausal women. Most calcifications are coarse and the so-called popcorn calcifications are pathognomonic for fibroadenoma. When a fibroadenoma starts to calcify the calcifications are small and punctate, and may be difficult to differentiate from malignant calcifications. On ultrasonography, fibroadenomas are usually circumscribed, oval lesions with homogeneous internal echo structure. They are usually isoechogenic with fatty tissue and therefore visible in dense glandular tissue. Particularly in older women the echo structure may be more heterogeneous due to fibrosis and calcifications. In such cases there may be posterior shadowing. In younger women most fibroadenomas show posterior enhancement. The anteroposterior diameter of a fibroadenoma is usually smaller than the transverse diameter. A fibroadenoma is diagnosed through mammogram, physical exam, fine-needle aspiration and, at times, a biopsy. On a mammogram (x-ray of the breast), a fibroadenoma appears as an oval-shaped, well-defined lump with a smooth surface. In contrast, a cancerous lump appears as a more irregularly shaped lump that extends out into the surrounding tissues.

In a physical examination, a fibroadenoma feels slippery and smooth, like a hard marble, and moves freely within the breast. However, it is not always possible to tell the difference between a fibroadenoma and a fluid-filled cyst. Therefore, your doctor may decide to do a simple procedure in the office called "fine-needle aspiration".

The fine-needle aspiration procedure takes only a few seconds and causes no more pain than having a blood test. The procedure involves inserting a very thin needle attached to a syringe into the lump (see Figure 1). If the lump is a cyst, the fluid in the cyst will be drawn into the syringe, and the lump will disappear. If the lump is solid, a small sample of cells will be removed and examined under a microscope to rule out the possibility of a cancerous tumor.

At this point, your doctor will evaluate all of the test results, including the mammogram, physical exam, and results from the cell sample. He or she will also consider other factors such as how long you have had the lump, your age, and medical history. Even if the cell sample shows benign (non-cancerous) cells, your doctor may still recommend a final procedure to confirm this result, called a "surgical biopsy."

A surgical biopsy is a minor surgical procedure that removes a small piece of the lump, or the entire lump itself if it is small. A surgical biopsy is done using a local or general anesthetic. The tissue from the lump is then sent to a laboratory to confirm whether it is benign.

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All information is intended for reference only. Please consult your physician for accurate medical advices and treatment. Copyright 2005,, all rights reserved. Last update: July 18, 2005