Expert: Claes-Gustaf Nordquist, M.D. - 5/28/2009

Question
"Hello,
I am 40 years old.  When I was 29 I discovered that I had a 12cm (13x8) lump in my breast.  I was told that it was a fibroadenoma with refined borders and that I should not worry.  I then had routine check ups annually until I was 34 and the lump remained the same size and shape.
2 months ago, as a result of recurring breast pain, I decided to do a mammography.  The result was that the lump was the same size but they concluded that now there are also some calcifications.  They recommended a fine needle biopsy.
The result of this first biopsy revealed that I had some malignant cells and the lump was a ductal carcinoma G2.  They soon after did a core biopsy.  To my surprise, this second biopsy revealed that the lump was a fibroadenoma and calcifications.
Now I don't know how to interpret these results.  One doctor said that I'm clear and I should just remove the lump for peace of mind.  Another said that she still believes that there are some malignant cells and she was lucky to have seen them from the first biopsy since they didn't appear in the second.
My question:
1. How is it possible that in one biopsy there was a presence of malignant cells and in the second biopsy (the one that should be more accurate) there are none?
2. Is it possible for a biopsy to falsely detect malignant cells?  If so, how?  Are there some cells that look like malignant cells and then with the second biopsy it clarifies that they are not?"


Answer
There are always some uncertainties with every test. Also the fine needle and the core needle may have hit different parts of your lesion. To be sure I agree that your lesion should be removed as a "lumpectomy"! Then based on the pathology report of the whole of your lesion we can decide what more to do - if indeed anything! Good luck! Please do keep me posted!