I have never seen accessory nipple cancer. However, I do have a supernumary nipple! Mine is located a few inches under my left breast, and it is very tiny like a small mole. However, if you look closely, it is really a tiny nipple. There is no obvious breast tissue there that I can see. It's actually a quirky kind of thing to have. Nearly every health practicioner that I see gets excited when they see it. LOL! Apparently, these "extra" nipples can come in all shapes and sizes. I saw a slide show in nursing school
given by a lactation consultant, and she discussed accessory nipples. Most people that have them, she said, have the tiny ones that look like a small mole. And yes, some of them will produce milk when a woman becomes pregnant. Good point, though, we still need to examine this area too, even if it is super small.