Brand Spanking New&clueless..Help with what this all means..

I am 56, healthy and active with no family history of breast cancer. I have had annual mamograms ..forever..

I felt a lump 4 years ago.. it was a cyst..No further issues. I have now felt another lump at the same location of the last cyst..But this time there was some tingling and itching.MyOct 2014 negative no issues..I go in for a mammogram with a specialist. Radiologist is concerned,so schedules me for needle biopsy( 2 suspicious sites).Here is the path report. Only left breast involved

Good news- I think..Estrogen and Progesterone Pos and Her2 Negative (0) but...Ki-67 HIGH (80%)

areaA- DCIS at least 1.0cm nuclear grade 2, Comedonecrosis

Area B- Microinvasive ductal Carcinoma 1.5mm thats MM! 2 foci

Only Microinvasion present

Associated DCIS grade intermediate central luminal necrosis present

I thought this was a "great cancer" to have.. but my breast surgeon look like shes highly concerned and ordering another biopsy and a breast MRI.

She is one of the best and I have a family member that is an MD.BS is saying mastectomy ..why is she saying this from these results..Can anyone help me with what the BS is thinking is so wrong that has me meeting with a platic surgeon asap..I thought standard thinking was a lumpectomy..what am I missing?