text: A supernumerary nipple is an additional instance of nipple occurring in mammals, including humans and monkeys. They are often mistaken for moles. Studies variously report the prevalence of supernumerary nipples as approximately 1 in 18 and 1 in 40.
  The nipples appear along the two vertical "milk lines", which start in the armpit on each side, run down through the typical nipples and end at the groin. They are classified into eight levels of completeness, from a simple patch of hair to a milk-bearing breast in miniature.
  Types
  Polythelia refers to the presence of an additional nipple alone, while polymastia denotes the much rarer presence of additional mammary glands.
  Although usually presenting on the milk line, pseudomamma can appear as far away as the foot.
  A possible relationship with mitral valve prolapse has been proposed.
  Clinical significance
  Clinical presentation
  It may remain undetected. Occasionally, the supernumerary nipple is noticed when hormonal changes during adolescence, menstruation, or pregnancy cause increased pigmentation, fluctuating swelling, tenderness, or even lactation.
  Associations
  It is said to be found in association with many syndromes and other conditions:
  McKusick–Kaufman syndrome
  Char syndrome
  Simpson–Golabi–Behmel syndrome