Having extra nipples (often known as a third nipple) or polythelia is often mistaken for moles by many. Approximately 1 in 18 humans would have an extra nipple. These extra nipples are usually found along the two vertical “milk lines” which can vary in number from one to as many as eight or more. One should be aware that the presence of “extra nipples” or polythelia has a strong association with kidney disease.
Supernumerary nipples from the work of Erik Strandberg (Wikimedia commons)
Fast Facts about Polythelia
There may be a possible relationship with mitral valve prolapsed (heart valve problem).
Kidney abnormalities associated with polythelia include: cysts, duplications of the kidney, and kidney cancer
14% of patients with no family history of polythelia have kidney abnormalities
32 % of patients with a family history of polythelia have kidney abnormalities
1-2% of general population may have kidney abnormalities.
19% of patients who had kidney cancer had extra nipples.
I recommend that physicians, families and friends of individuals who have "extra nipples" should be aware of the association of kidney abnormalities with polythelia. Routine physical examination, a renal ultrasound and urinalysis may be recommended in these patients.