What You Should Know About Phyllodes Tumors of the Breast

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Phyllodes tumors are rare breast tumors that start in the connective (stromal) issues of the breast. These tumors can be benign (harmless) or malignant (cancerous). They are considered sarcomas because of where they occur (in connective breast tissues), rather than in epithelial tissue (lining of ducts and lobes).

Phyllodes tumors take their name from the Greek word phullon (leaf) because of their leaf-shaped growth pattern. These tumors make up between 0.3 to 0.5 percent of female breast cancers, with an incidence of about 2.1 per million, mostly affecting women between ages 35 and 50 years of age.

Even though a phyllodes tumor may be benign, it is still considered a type of breast cancer, because it has the potential to become malignant. In fact, most phyllodes tumors are benign, but up to one in five will become malignant. 

Most women who are diagnosed with phyllodes tumors are premenopausal. In rare cases, adolescent girls may be diagnosed with this type of breast tumor. They are very rare in men.

Signs and Symptoms

Phyllodes tumors usually present themselves as a firm, smooth-sided, bumpy breast lump. They can grow fast, so if you notice one during a self-breast exam, you should have it checked out as soon as possible. 

Breast skin over the tumor may become reddish and warm to the touch. This type of breast tumor grows very fast—so much so that the lump can become noticeably bigger in a couple of weeks. If phyllodes tumors are not treated, they may break through the skin creating a skin ulcer.

Other symptoms may include those that are seen with other types of breast cancers, including:

  • Swelling in part in all or part of the breast
  • Nipple pain or a nipple turning inward
  • Breast pain
  • Skin irritation or dimpling (having the texture of an orange peel)
  • Redness, scaling and thickening of nipple or breast skin
  • Nipple discharge, other than breast milk
  • A lump in the underarm

Because a phyllodes tumor may resemble a fibroadenoma, these two conditions are often mistaken for each other. Fibroadenomas are solid, non-cancerous lumps usually in found in teen girls and women under age 35. 

Causes and Risk Factors

Causes of phyllodes tumors are unknown. They just seem to be more common as people age.  Certain factors may contribute to the growth of these tumors, including:

  • Injury to the breast
  • Increased levels of the female hormone, estrogen
  • Breastfeeding
  • Pregnancy         

The two strongest risk factors for phyllodes tumors are menopause and being female, although any woman of any age can develop one of these tumors. Phyllodes tumors are rarely seen in men.


On a mammogram, a phyllodes tumor will have well-defined edges. However, neither a mammogram nor breast ultrasound, can distinguish clearly between fibroadenomas and benign or malignant phyllodes tumors. This type of breast tumor is not usually found near microcalcifications, as seen with other types of breast cancers.

Cells from a needle biopsy can be tested in the lab but seldom give a clear diagnosis, because the cells can resemble carcinomas and fibroadenomas. An excisional biopsy offers a better sample of cells and can result in an accurate diagnosis of a phyllodes tumor.

Excisional Biopsy

An excisional biopsy involves the removal of the entire lump or area of abnormal tissue and a portion of normal, healthy tissue.

Some researchers believe the best way to diagnose a phyllodes tumor is with an excisional biopsy. A core needle biopsy sample will not allow for examination of the entire tumor, which is important in making a correct diagnosis. 

Once the biopsy sample is taken, a pathologist will look at the tissue under a microscope and classify the tumor a benign, borderline or malignant. Most breast cancers are classified as stages 1 to 4, but that is not the case with phyllodes tumors. Two characteristics are considered: the speed at which the cells are dividing and the number of irregularly shaped cells in the tissue sample.

A benign tumor has well-defined edges, connective tissues that appear normal, no overgrowth to connective tissues, and cells that slowly divide.  A malignant tumor, on the other hand, does not have defined borders, has cells that divide quickly, overgrowth of connective tissues and abnormal-looking connective tissues. Malignant tumors may also expand outside the breast.

If a pathologist determines the tumor is borderline, that means it falls between benign and malignant and has characteristics of both types. 


Overall, the prognosis for benign phyllodes tumors is very good. And most people with malignant phyllodes tumors can be cured with the right treatment. However, it is possible for these tumors to recur in breast tissue and even metastasize to the lungs.

For people who have a diagnosis of borderline or malignant tumor, the prognosis will vary. Borderline tumors have the potential to become cancerous, and even after surgery, if some cells remain (although rare), they can metastasize.

Malignant tumors can recur even two years after treatment and may spread to the lungs, bones, liver and chest wall. That said, few malignant phyllodes tumors will metastasize although lymph nodes may be involved.


Surgery to remove a phyllodes tumor is the standard treatment. This type of tumor does not respond well to chemotherapy or hormonal therapies, although radiation might be helpful.

If a tumor is relatively small and benign, it may be removed with a lumpectomy. Large benign tumors may require a mastectomy, so as to remove both the tumor and a clean margin of breast tissue.

Malignant tumors are removed with a wide local excision (WLE) or mastectomy to remove as much of the affected tissue as possible. Your doctor may also suggest radiation therapy to keep the cancer from coming back.

A Word From Verywell Health

After removal of a phyllodes tumor, you should not have any problems, aside from any surgical pain or scarring. The risk for this type of tumor spreading out of the breast is low even with malignant tumors, so outlook for most people is generally good and treatment is usually very effective.

Benign tumors rarely return, but you should see your doctor regularly and get yearly mammograms to check for recurrences. Recurrence is higher for malignant tumors. If you notice any new symptoms during a breast self-exam after the tumor has been removed, it is a good idea to see to your doctor immediately to make sure you do not have a recurrence or a new health concern.

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