From cyst to something that needs a biopsy?

[mom2clre]

I am 41 years old and have a 4 1/2 year old daughter. I had a mammogram in late April and they found something in my left breast that needed further exam.  In early May I had an US and was told that it was a cyst about 4 mm big. I saw it on the US screen and it was round in shape and clear looking, I was told that could indicate it was filled with fluid (?).  I saw my ob/gyn twice during this time to keep an eye on it. I returned for a follow up US this last Friday and was told that it had changed a great deal.  They also did another mammogram. The radiologist that spoke with me said that he had never seen something change so much in such a short period of time.  He asked me if I was sure that this was the same lump? Wouldn't they be better able to determine if it was indeed the same lump being they are looking on the US.  It was in the exact same location, that I had felt previously.  He further said that my breast were very dense, and that is why on the new mammogram they couldn't see this lump which is now 1.26 cm by ~ 1.16 cm. I was told that I need a needle biopsy.  He tried to call my ob/gyn, but the office was closed. Is this common for a "cyst" to turn into something that needs a biopsy in just five months?  I searched the web and felt pretty confident that cysts didn't change into anything serious.  Also is it true that 80% of biopsies are negative for cancer?  My breasts have always felt lumpy.  I do feel the lump now that I know what to look for, but why don't they see this on the mammogram?  How confident can I be in the future that my mammograms will detect problems?  Thank you for your time.

[CCF-RN,MSN-rf]

Dear mom2clre:  Cysts can and do change in size - often with one's menstrual cycle.  The question is does this still look like a cyst?  Or, has it changed to something that needs further evaluation.  Since you have dense breast tissue, mammogram may be difficult to read.  An ultrasound can often differentiate between solid and cystic.  It is true that a significant percentage of breast biopsies do turn out to be negative.  Mammogram is not a perfect test but until something better is developed, mammogram along with clinical exam and breast self exam is still a fairly good test.

[surgeon]

mammograms are able to detect certain things; physical exam is able to detect certain things. They aren't always the same, which is why you always need both for good screening. When there's a feelable lump, and some sort of shadow on mammogram, it sometimes is not possible to be easily certain they are the same. There are ways to be certain, for example by marking the lump before taking the picture. As to the "cyst." A cyst, by definition, is a fluid collection, and harmless. If the shadow was shown to be a cyst, and is still one now, then it remains of very low concern: the issue is how certain they are that it has the characteristics of fluid. 4 mm is small enough that it's more possible to be wrong. At 1.2 cm, it should be pretty easy to say whether it's fluid or not. Such a growth rate is not at all unusual for a cyst. A growing cyst does not necessarily need biopsy as long as it's sure that's what it is. In your case, it sounds like it's not certain the thing seen now is the same as the thing seen before. And if it's feelable now, it takes about 5 seconds to poke a needle into it (usually hurts very little) which can prove once and for all what it is. What's needed is a person (usually a breast surgeon, as opposed to an ob-gyn) who can both examine you and review the films and decide what is what and how to go about figuring it all out.

[PBREARD]

I would definitely find a breast surgeon, as I did.  What I always thought was a small cyst, suddenly changed.  I too have dense breasts and the radiologist could see the small cyst, but due to the density was not sure what else was there.  I had a needle biopsy which showed abnormal cells. My surgeon suggested removal of the whole thing to make a final diagnosis, which we are still waiting for.  But, what surprised me most was the true size of the cyst which turned out to be the size of an egg.
I did not feel that or did radiologist see that due to the density.  I am feeling positive about the final results and will know soon.  But, finding a surgeon who deals with breasts only is the way to go.  Good luck.