You Might Have A Spare Nipple, Innit

By Warren Hamilton Category: Human Anatomy 11th August 2026

Another daft thing about the human body: some folks have an extra nipple. Proper spare. Not on the head, not on the foot, just lurking along the old 'milk line' that runs from armpit to groin. It's called supernumerary nipple or polythelia. Sounds posh. It's basically a factory fault nature left in the margin.

It turns up in roughly one to five percent of people, depending who you ask. So yeah, you've probably met someone with one and nobody mentioned it because we are all well-mannered about odd bits. Sometimes it looks like a mole. Sometimes it's a little patch of darker skin. Other times it actually looks like a tiny nipple. Imagine that. Your torso's got a spare button.

Embryology does this daft thing where the milk lines form and then most of them disappear. Usually just the chest bit stays. Occasionally one bit forgets to leave. There you go. Developmental hangover. It can be totally harmless. It can also have actual breast tissue. Which means, in puberty or pregnancy, it might swell or even leak milk. People get surprised. Fair play.

Most times they're cosmetic. Folks get them cut out if they bother them or for hygiene reasons. Surgeons are used to it. And yes, in rare cases the extra tissue can develop the same problems real breasts can get, including the odd cancer. Rare, but real. Doesn't help the drama, does it?

I remember years ago a mate showed me one on his rib and wanted to know if it was witchcraft. I said, "No mate, it's biology being lazy." He kept it. Said it made him feel like a limited edition. People are weirdly proud of their quirks.

So next time you spot a suspicious mole somewhere odd, don't scream. Could be nothing. Could be your body's idea of a spare part. Either way, it's proper human, utterly boring to nature, and brilliant to talk about down the pub.