Difference between cyst and cancer.....

[Trouble 72]

I just saw the x-ray of my mammogram.  The woman who did the mammogram told me it "looked" like it would be a cyst.  I am wondering what the difference in appearance is between a cyst and a cancer.  How can one tell if this is a cyst, by looking at it.

Thank you,
Trouble 72

[CCF-RN,MSN-JS]

Dear Trouble 72, There is not an absolute way of differentiating a cyst from cancer on a mammogram, however, there are certain findings that may be more suspicious one way or another.  For example, a well defined area may be more likely a cyst.  They may decide to do an ultrasound which is used to help differentiate between a fluid-filled structure (cyst) and solid area.

[surgeon]

a cyst is a fluid filled area, and they are typically very round with smooth borders. Cancer has irregular borders which are fuzzy, sort of star-shaped, because it tends to grow outward in all directions. So a very round shadow nearly always is non-cancerous; you can't tell if it's a cyst for sure on a mammogram, because you can't tell if it's liquid. The other common very round shadow in a breast is a harmless tumor called a fibroadenoma. The way to tell for sure, if it can't be felt to poke a needle in it to look for fluid, is with an ultrasound.