Pathology and MRI Report different

Is is normal for the patholgy report to say that DCIS is 0.7cm and a week later the MRI says 5cm. I'm not sure if I'm getting correct information from my Dr. He gave me options of Lumpectomy or Mastectomy but when I talked with him he's pushing mastectomy and don't want to do a Lumpectomy. I'm confused on why he wants to do a Mastectomy and he's not considering what I want.

[zouzi]

Hi,
Treatments on how to proceed with DCIS diagnosis are related to many factors. For example a doctor has to consider the size of the tumor,the grade, and the breast cosmetic appearance if the tumor is large.Also additional tissues has to be removed to obtain clean margins.
Yes, it does happen to have a difference in tumor sizes with additional tests .Only the final pathology report (After surgery) will give the exact measure of the lump.
If your doctor is pushing for a Mastectomy,there must be a good reason to suggest it since he would know your case the best after considering the many factors mentioned above.
If  you have any doubt on how to proceed,you could seek the opinion of another breast Specialist so that you are convinced about which option is best in your case.
Please check this website,it has valuable info and you may find it helpful.

http://www.dcis.info/dcis.html

Wishing you all the best and good luck!.