Phyllodes Tumor Definition and Treatment

Dr. Harness explains that phyllodes tumors are benign tumors in the breast, the indicators for its development, and potential treatment for the patient.




Jay K. Harness, MD, FACS: Among the benign tumors that I deal with, a phyllodes tumor, which is generally a benign breast lesion, is one of the more interesting of what is called the biphasic tumors of the breast.

I have done a fibroadenoma video here at and talked a lot about what are biphasic benign tumors of the breast.  They are made up of one component of the connective tissue, the other component of the epithelial cells or the cells that lying ducts.  Interestingly, the fibroadenomas arise out of the terminal ductal lobular units where actually where breast cancer arises from.

So one of the really unusual kinds of tumors here is called a phyllodes tumor.  One of the old terms for this was cystosarcoma phyllodes.  Phyllodes make up of tiny fraction of all lumps, if you will, in the breast in the neighborhood of 0.3% and of the fibroadenoma class, if you will, or biphasic class, the phyllodes tumors only makeup roughly around 2.5%, so they are very very unusual, but why we are concerned about them?

Well, first of all, if we have a fibroadenoma that is getting bigger and bigger and bigger, in the back to my mind is, could this be a transition to a phyllodes tumor.  Further, the phyllodes which were general and almost always benign, they cannot go on to become malignant.  Very very unusual diagnosis, but it can happen.

The other thing that is unique about a phyllodes tumor is the way that they can locally recur, some estimates are upto 30% chance.  After you take the phyllodes tumor out, that it can reoccur right in the same neighborhood, so therefore having a rim of some normal tissue around the phyllodes tumor is really really important.

Generally, we see the phyllodes tumors in the age group of around 45 to 49.  I am looking at some notes just so that I am right up to a snap on this, the question then becomes how do we differentiate a benign phyllodes tumor from a malignant phyllodes tumor and further within the malignant phyllodes tumor there are high grade and low grade tumors and a tiny percent of these malignant phyllodes tumors can actually metastasize elsewhere in the body, almost exclusively to the lungs

This is again going back to something that I have harped on time and time again about the multidisciplinary team, about the importance of the breast pathologist and having the experience to (a) recognize a phyllodes tumor, (b) knowing if it is malignant or not, (c) if it is a high grade or low grade or even importantly, sending this lesion off to other experts around the country to help out with the diagnosis.

I worry about phyllodes a lot with big big fibroadenomas.  The core biopsy generally cannot give us a complete answer here.  We really need to take the whole thing out.

We recently received a question from someone concerned about “Gee, why can’t the core biopsy figure out what is going on here and why does it take so much time to also tell me what is going on.

That is the nature of the game and that often we need to take the whole lesion out in order to see in total make multiple multiple slides up of the lesion in order to know exactly what is going on.

Remember if you are one of those people who has a phyllodes lesion, are the margins negative because of the chance it can come back, is it by any chance malignant at all and if there is any question at all in the mind of the pathologist where you are residing, please ask him, send the slides off to an expert who can give you a bottom-line reading whether it is completely benign, malignant and the things I have shared with you.

Dr. Jay K. Harness is a board certified surgeon currently treating patients at St. Joesph Hospital in Orange, CA. Dr. Harness specializes in complete breast health, breast cancer surgery, oncoplastic reconstruction, genetic screening, management of breast health issues, risk assessment and counseling. Dr. Harness is the medical director for Breast Cancer, and guides this first ever social media show’s information by drawing on his former leadership experience as the President of the American Society of Breast Surgeons and Breast Surgery International. Dr. Harness graduated from the University of Michigan, Ann Arbor in 1969 and spent time early on in his career at the University of Michigan Medical Center.

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