Simple cyst with calcification

I am a 38 year old mother of two.  My doctor reports that a recent US showed a simple cyst with calcification.  I have had several issues with breast cysts as well as one breast tumor (benign) and during those exams they are always saying it's good when there is no calcification. They tell me that calcification is actually how they will know the mass is solid and may be cancerous.  So the idea of calling it a "simple cyst" yet saying it shows calcification confuses me.  Can you shed any light on this issue?  I will be having another ultrasound in July.
Thank you