CT Scan Results - Are Lytic Lesions Always Mets?

My mom who is an 11 year Stage 3 breast cancer survivor had an xray done for shoulder pain at the ER which was clear. A CT scan was ordered of the neck/chest/abdomen/pelvis because of her history and the results are suspicious for malignancy.

We are going stir crazy waiting for an appt. for biopsy and she has a bone scan scheduled for next week. In the mean time I was hoping someone could share some insight about her results:

#1- Lytic lesion right head of clavicle with soft tissue density. Invades prox. right sternocleidomastoid muscle and 2 other lytic lesions in right sacrum + illiac bone. Left sclerotic lesion.

#2- Mild non-specific lymphadenopathy

#3- 6x3mm oblong lung nodule

#4 -No source seen.

Conclusion:

3 lytic lesions --> one in right clavicular head causing expansion and assoc. soft tissue density.

DDX: mets, myeloma, ? other?

Consider biopsy and bone scan.