Thanks for your reply. My LCIS in my right breast was discovered through mammogram. Since LCIS is not within my HMO ‘s guidelines for routine MRI, I figured that any follow up screening that would be offered to me, be it ultrasound or mammogram, would probably be less than optimal. I then decided to take the most aggressive approach to dealing with it, which was to ask for a double mastectomy. Post mastectomy biopsy of the breast tissue revealed that I had LCIS in the other breast as well. Thus, this shows that LCIS does not always show up on mammograms.