Skin Mets to Arm Pit?

I wondering if anyone has had skin mets to the armpit area.

I had a mastectomy, 15 positive lymph nodes, and radiation to the breast and axilla. I also had chemo and herceptin. I finished radiation 9 months ago. I have a rash in my armpit that's been there for about 2 months. It doesn't hurt, it doesn't itch and it hasn't gotten worse.