An Overview of Phyllodes Tumors of the Breast

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Phyllodes tumors are rare breast tumors that occur in connective breast tissue. These sarcomas get their name from their leaf-shaped growth pattern (phullon means leaf in Greek). Phyllodes tumors are fast-growing, but usually benign. Some, however, can be malignant or turn into breast cancer, as is the reality in up to one in five cases.

These tumors make up 0.3% to 0.5% of female breast cancers. Most women who are diagnosed with phyllodes tumors are premenopausal (most commonly, in their 40s). In rare cases, adolescent girls may be diagnosed with this type of breast tumor. They are very rare in men.

Also Known As

Phyllodes tumors are also called cystosarcoma phyllodes and phylloides tumors.

Symptoms

Phyllodes tumors usually present themselves as firm, smooth-sided breast lumps. This type of breast tumor grows very quickly—so much so that the lump can become noticeably bigger in a couple of weeks. Breast skin over the tumor may become reddish and warm to the touch.

If you notice one during a self-breast exam, you should have it checked out as soon as possible. Untreated phyllodes tumors may break through the skin and create an ulcer.

Other symptoms may include those seen with breast cancers in general, including:

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

Causes

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

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

Li-Fraumeni syndrome, an inherited genetic condition, also increases one's risk of phyllodes tumors.

Diagnosis

Because phyllodes tumors are similar in presentation to fibroadenomas (i.e., firm, well-defined), these two conditions are often mistaken for one another.

Unfortunately, neither a mammogram nor breast ultrasound can clearly distinguish between the two (regardless of whether or not a phyllodes tumor, if present, is cancerous or not). Rather, an excisional biopsy is required.

Excisional Biopsy

Cells from a needle biopsy can be tested in the lab, but seldom give a clear diagnosis because they can resemble carcinomas and fibroadenomas. That is why an excisional biopsy is needed. It removes the entire lump (or area of abnormal tissue) and a portion of normal, healthy tissue for testing.

Once the sample is taken, a pathologist will look at the tissue under a microscope and classify the tumor as one of the following:

Classification Tumor Features
Benign (non-cancerous) Well-defined edges; normal-appearing connective tissue; no overgrowth; slow-dividing cells
Malignant (cancerous) Poorly-defined borders; abnormal-looking connective tissue; evidence of overgrowth (possibly outside the breast); fast-dividing cells
Borderline

In between benign and malignant; has characteristics of both types and the potential to become cancerous

Treatment

Surgery is the standard treatment to remove a phyllodes tumor. 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 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.

Your doctor will recommend close monitoring, including regular mammograms, to watch for tumor recurrence.

Prognosis

Overall, the prognosis for benign phyllodes tumors is very good; they rarely return.

For people who have borderline or malignant phyllodes tumors, prognosis can vary, but is generally positive; most cases can be cured with the right treatment. However, it is possible for cells to remain after surgery, causing a tumor to recur even just a few years after surgery.

Malignant tumors may metastasize to the lungs, bones, liver, and chest wall. That said, few cases advance in this way, even though lymph nodes may be involved.

A Word From Verywell

If you notice any new signs or symptoms during a breast self-exam after the tumor has been removed, it is a good idea to see to your doctor immediately. While phyllodes tumors can recur, they often do not, and you should be assessed for other potential causes of your breast changes.

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