Understanding Mammogram Shadows: What Could It Mean?

Question
My mother in law is 63 and has yearly mammograms because her mother and sister had breast cancer.  Her last mammogram had a shadow that was not there the year before.  She is going for an ultrasound and she can't palpate the lump.  Could this be a calcification, if so wouldn't they have said that?  I am concerned and I know she is to.  My father in law passed away a year and a half ago and she is alone.  What do you think?

Answer
A "shadow" is not a calcification. A calcification looks in a very typical way and can hardly be missed, but anything new in a 63 year old woman with this family history can not be ignored. I strongly suggest that her mammogram should be complemented not only with an ultrasound scan but also with a breast MRI scan and that a needle biopsy at least of the lesion should be done!