Your mother has been diagnosed with metastatic adenocarcinoma of axilla (with unknown primary) almost 2 months ago.
I hope that in the meantime she has tests (MRI breast, PET CT, ER, PR, and other IHC stains on biopsy specimen, tumor markers, genetic tests, etc) to determine the primary site from where the cancer originated, and has started treatment for it. Many women with axilla adenocarcinoma and normal mammograms have breast cancer, which may be identified in some of them by breast MRI or on pathological examination of surgically removed breast.
If she has occult breast primary with axillary involvement only, then she has stage 2 breast cancer. (However, we need to confirm that indeed she has no other metastases).
One approach to treatment of women with axillary node adenocarcinoma with unknown primary involves breast surgery followed by chemotherapy and radiation.
Please discuss in detail with the treating oncologist.
Best of Luck, and God Bless!
Thank you for taking the time to respond to my questions.