Ectopic Breast Cancer in the Axilla After Bilateral Breast Cancer Surgery: A Case Report and Literature Review.

Ectopic breast cancer (EBC) is a rare condition, and there have been no reports of axillary EBC as a third primary breast cancer after bilateral pectoral breast cancer (PBC) surgery. A woman presented with a mass in her axilla, which was located just beneath the skin. On ultrasound (US) examination, it appeared oval-shaped with uniform internal echoes and relatively clear boundaries.