Scientists have discovered a full-grown nipple on the foot of a 22-year-old woman.

The startling discovery is the first of its kind, as between one to five percent of the population are believed to suffer from the head-scratching condition, which is clinically called supernumerary breast tissue, according to a report released in the scientific journal Dermatology Online.

Extra nipples are prone to exist above the waist.

Third and fourth nipples have been found on the likes of King Henry VIII of England's wife Anne Boleyn, the actor Mark Walhberg and pop star Lily Allen.