By the way, less than half a centimeter is less than 1/4 inch and your Doctor is right that it's very small.
Hi,
Calcifications can be cause by many benign conditions such as calcifications in a dilated milk duct,cysts,fibroadenomas etc..and not necessarily indicative of something more serious.
The appearance of suspicious calcification on x-ray, gives clues to the radiologist,but not definite answers,so it is standard procedure in most cases to biopsy the area because it's the only way to rule out cancer.
Try not to worry too much because very often biopsies done on suspicious calcification return a benign finding, but if unfortunately it does not,then the cancer would be at a very early stage and almost 100% curable.
I hope that your biopsy results will state benign findings.
Best wishes and good luck!...