Dear Dr G,

In the spirit of Pink October, I am hoping you can help me with some troubling matters on my chest.

I am a female university student in my early twenties.

As far as I can remember, I have had two moles on each side of my chest, next to my nipples.

Although a bit unsightly, these two lumps were not troubling at all.

Things began to change after I started my puberty.

I noticed the moles have become bulkier and darker in colour.

During my menstruation, the lumps are somewhat uncomfortable.

Another observation is when I am aroused during sexual intercourse: I noticed the lump to be more prominent and sensitive.

My partner tells me these lumps are likely to be two extra nipples.

I have never heard of such nonsense and would like to put Dr G on the spot to set the record straight.

Is there such a thing as an extra nipple? Why does it appear?

How many types of extra nipples are there, and where do they usually appear?

Can anything be done about my extra nipples? They are rather unsightly.

Lastly, can men get extra nipples, too?

Incidentally, why do men have nipples when they are functionless?

I am so confused. Please help me get this double trouble off my chest.

Yours truly,

Erogenous Ernie

A supernumerary nipple occurs when an extra nipple or nipples appear, in addition to the pair of nipples in the usual location. In medical terms, this is also known as ectopic nipples, accessory nipples, vestigial nipples, or triple nipples.‌ Such a phenomenon is relatively common, occurring in between 1% and 5% of the population.

Extra nipples in humans are completely harmless, and many people with an extra nipple may not realise that they have one, as they are often mistaken for moles. Extra nipples form during development in the womb, appearing along the milk line, or the mammary ridge. This location, anywhere between the armpits and groin, is where breast tissues potentially develop and regress in mammals.

In human embryogenesis, the mammary ridge appears as a narrow skin thickening in both sexes during the first seven weeks of pregnancy. As this occurs before sexual differentiation, this explains why men have nipples too. After the initial development of the milk line, they go into regression. Most humans have two nipples, but in some cases, additional ones will develop, usually growing along the milk line.

The ectopic nipples may appear with or without the accessory glandular tissues. When the supernumerary nipple appears alone, it is termed polythelia. However, when an extra nipple is connected to the breast tissues and glands, it is known as polymastia.

Supernumerary nipples can be classified into six categories depending on their existence with or without the pigmented skin around the nipple (areola) and the underlying breast tissues. The existence of areola and glandular tissues will also be influenced by hormonal changes and sexual stimulation.

The male and female breasts and areolae develop similarly in the fetus and have the same number of nerve endings. At puberty, male breasts remain rudimentary, but female breasts develop further into adulthood. The influence of estrogen and progesterone determines the degree of enlargement of both breasts. Therefore, even the third nipple will experience some degree of change in engorgement and sensitivity during the menstrual cycle.

The human breasts, especially the nipples, are highly sensitive with erogenous zones for both men and women, and the number of nerve endings of the breast is similar irrespective of size. The tactile stimulation often has a heightened sensitivity and stimulation that can generate sexual arousal and excitement. Nipple stimulation is a common, but less talked about, mode of human sexual practice, either by itself or as part of a sexual experience with a partner.

Engorged nipples are typically a prominent indicator of female sexual arousal; similarly, male breasts may protrude and become erect when erotically inclined. Such sexual sensitivity may also apply to the ectopic nipple. Supernumerary nipples are essentially harmless. Some scientific publications link the condition with kidney cancers and end-stage renal diseases; however, such associations are exceedingly rare.

Most individuals with ectopic nipples are oblivious to their additional nipples. However, some may be bothered by them and request surgical removal for cosmetic purposes. The removal process itself is usually a minor outpatient procedure under local anaesthesia, with minimal complications. The embryological development of a human being is a curious form of creation.

Some may be scarred with a disabling malfunction of an organ, others may just be oblivious of a variation of the norm, such as a harmless supernumerary mammary gland.

Charlie Chaplin famously said: “I do not have much patience with a thing of beauty that must be explained to be understood. If it does need additional interpretation by someone other than the creator, then I question whether it fulfilled its purpose”

When Dr G is put on the spot by troubled men and women, with a mole-like lesion on their chests and curious about a possible extra nipple, his view is: “The extra nipple is just like a thing of beauty that needs no explanation nor understanding. Questioning whether it fulfils its purpose is pointless, as the additional interpretation by the creator is lacking. Why interfere with nature when the double trouble may just actually be doubly pleasurable?”