What You Should Know About Phyllodes Tumors of the Breast

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Phyllodes tumor is an uncommon type of breast tumor, which can be benign (harmless) or malignant (cancerous). This type of tumor is called a sarcoma because it occurs in the connective tissue (stroma) of your breast, 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.

Phyllodes tumors account for 0.3 percent to 0.5 percent of all breast cancers. Even though the tumor may be benign, it is still considered a type of breast cancer, because it has the potential to become malignant.

Phyllodes tumor is also known as phylloides tumor, PT, cystosarcoma phyllodes, cystosarcoma phylloides and giant fibroadenomas.

Signs and Symptoms

A Phyllodes tumor will feel like a firm, smooth-sided, bumpy (not spiky) lump in your breast tissue. 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 very noticeably bigger in a couple of weeks. If Phyllodes tumors are not treated, they may break through the skin creating a skin ulcer.

Because a Phyllodes tumor may resemble a fibroadenoma, these two conditions are often mistaken for each other. Most women who are diagnosed with Phyllodes tumor are premenopausal. In rare cases, adolescent girls may be diagnosed with this type of breast tumor. They are very rare in men.


On a mammogram, a Phyllodes tumor will have a well-defined edge. Neither a mammogram nor a breast ultrasound, however, can distinguish clearly between fibroadenomas and benign or malignant Phyllodes tumors. This type of breast tumor is not usually found near microcalcifications. 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 open surgical biopsy, which results in a slice of tissue, will provide a better sample of cells and will result in a proper diagnosis for a Phyllodes tumor.

An Italian study comparing mammograms, ultrasounds and breast MRIs of Phyllodes tumor reported that MRIs gave the most accurate image of these tumors and helped surgeons plan their operations. Even if the tumor was quite close to the chest wall muscles, the breast MRI could give a better image of a Phyllodes tumor than a mammogram or ultrasound.


Most breast cancers are classified as stages 1 to 4, but that is not the case with Phyllodes tumor. After a surgical biopsy, the pathologist will study the cells under a microscope. Two characteristics are considered: the speed at which the cells are dividing and the number of irregularly shaped cells in the tissue sample. Depending on how the cells meet these criteria, the tumor is classed as benign (harmless), borderline or malignant (cancerous). Most Phyllodes tumors turn out to be benign.

Unlike ductal and lobular carcinomas that have a noninvasive stage (stage 0 or carcinoma in situ), phyllodes tumors do not. Epithelial cells have something known as a basement membrane. In very early epithelial breast cancers (such as ductal and lobular tumors), the cancer may be discovered before it has broken through this membrane. Since ductal carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS) may be found in this noninvasive stage, they should be, in theory, 100 percent curable. Phyllodes cancerous tumors are sarcomas, meaning that come from mesothelial cells. These cells do not have a precancerous or noninvasive stage (stage 0) and are all considered invasive at the time of diagnosis.


Your prognosis, or outlook after treatment, is very good for a benign Phyllodes tumor. There is a low chance of recurrence for a Phyllodes tumor if you are 45 or older. For people who have a diagnosis of borderline or malignant tumors, the prognosis will vary. Borderline tumors have the potential to become cancerous, and even after surgery, if some cells remain (although in rare cases) they will metastasize. Malignant tumors can recur even two years after treatment and may spread to the lungs, bones, liver and chest wall. That said, less than 5 percent of these tumors will metastasize. Sometimes lymph nodes are involved as well.


Surgery to remove a Phyllodes tumor is the standard treatment. This type of tumor does not respond well to radiation, chemotherapy or hormonal therapies. If your 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.

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