Femur tumor--b9 or mets? Anyone been there?

I have had knee pain for months, but never related it to my CA.  I had a knee MRI last week which is "worrisome" for mets--completely unexpected, we were looking for torn cartilage.  Two areas in the distal femur (they only MRI'd the knee) and some erosion of the cortex.  PET Monday. Oncologist says on a 1-10 scale (10 the worst) her concern is a 6.  If the PET is positive, a biopsy.  If negative, a bone scan.

I also had rising tumor markers last year, but after a clean PET , we stopped testing for them. 

My anxiety is sky high.  Has anyone had a b9 tumor of the bone.  She said another possibility is a hermangioma.  Thanks, Jody