What is supernumerary nipple

Supernumerary nipple is a common, minor birth defect that consists of an extra nipple(s) and/or related tissue, in addition to the two nipples that normally appear on the chest. Supernumerary nipple is also known as accessory nipple, ectopic nipple or extra nipple. Most supernumerary nipples do not cause symptoms or complications. They often are small and go undetected. Sometimes supernumerary nipples are first noticed during puberty, menstruation, or pregnancy when hormonal changes affect breast tissue.

The prevalence of supernumerary nipples varies geographically. The prevalence is 0.22% in a Hungarian population ¹, 1.63% in African American neonates ², 2.5% in Israeli neonates ³, 4.7% in Israeli Arabic children ⁴ and 5.6% in German children ⁵.

The incidence of supernumerary nipples is similar in males and females. Some studies have supported a slight male predominance with estimates of male-to-female ratio as high as 1.7:1 ⁶.

A supernumerary nipple is distinct from:

• Polythelia, which is the presence of supernumerary nipples without accessory glandular tissue
• Supernumerary or accessory breasts, which may or may not have nipples.

Supernumerary nipple can be present with no other tissue (polythelia); with some related tissue; or with breast tissue and ducts (then referred to as polymastia). Supernumerary nipples are usually located along areas of the body known as the “embryonic milk lines,” the lines of potentially appearing breast tissue. The embryonic milk lines extend on both sides of the body from slightly above the armpit, down the chest and abdomen, to the inner thighs near the groin.

Supernumerary nipples or breasts are found in up to 6% of the population. They present as either isolated findings or as features of genetic syndromes. Supernumerary nipples are usually not inherited but familial cases have been reported ⁶. These include:

• Ruvalcaba-Myhre syndrome
• Hay-Wells syndrome of ectodermal dysplasia

There have been some reports of an increased risk of urinary tract abnormalities in patients with supernumerary nipples, although this is disputed.

Most isolated cases of supernumerary nipples are sporadic, however they are familial in approximately 6% of reported cases. They exhibit an autosomal dominant pattern of inheritance with incomplete penetrance.

Most people do not need treatment, but the supernumerary nipple and related tissue can be removed for cosmetic purposes or if there is discomfort ⁷.

What causes supernumerary nipple?

Most supernumerary nipples are sporadic, although familial cases have been reported, including 1 report of a family who had supernumerary nipples in 4 successive generations. Familial cases are typically inherited in an autosomal dominant fashion with incomplete expressivity ⁸.

Supernumerary nipple is formed early on in the development of the embryo.

Week 4

• Mammary ridges form from thickening strips of ectoderm—these are the “milk lines” that extend from the axilla to the groin.

Week 6

• Mammary buds develop from downgrowth of epidermis from the ridges.

Week 8

• Failure of regression of mammary ridges result in the formation of the supernumerary nipple.

Supernumerary nipples commonly arise anywhere along the two vertical milk lines that originate in the axilla, descend through the region where nipples are typically situated, and terminate at the groin. About 5% of supernumerary nipples form outside the milk lines on the skin of the neck, back, vulva or thigh.

Supernumerary nipple associations with other diseases

Supernumerary nipple features are found in a number of syndromes, but, in most cases, it is probably a chance finding. These syndromes include Turner syndrome, Fanconi anemia, and other hematologic disorders ⁹; ectodermal dysplasia; Kaufman-McKusick syndrome; Char syndrome; Simpson-Golabi-Behmel syndrome; and epibulbar lipodermoids associated with preauricular appendages syndrome ¹. Isolated reports have linked supernumerary nipples to a number of other conditions, but in light of the fact that supernumerary nipples occur with a relatively high frequency in the general population, further studies are needed to validate the following associations:

Central nervous system associations are as follows:

• Epilepsy
• Migraine
• Neurosis
• Familial alcoholism
• Fetal alcohol syndrome
• Intracranial aneurism
• Neural tube defect
• Developmental delay

Gastrointestinal associations are as follows:

• Peptic ulcer
• Pyloric stenosis

Ears, nose, throat, and lung associations are as follows:

• Laryngeal web
• Ear abnormalities
• Accessory lung lobe

Skeletal associations are as follows:

• Hand malformation
• Vertebral anomaly
• Absence of rib
• Coronal suture synostosis
• Hemihypertrophy
• Arthrogryposis
• Scalp defects and microcephaly
• Dental anomalies

Cardiac associations are as follows:

• Essential hypertension
• Conduction defect
• Bundle-branch block
• Patent ductus arteriosus
• Congenital heart disease, atrial septic defect, and ventricular septal defect.

In 1979, Méhes ¹⁰ drew attention to the association of supernumerary nipples and other anomalies. The claim that 40% of supernumerary nipples investigated also had renal involvement was striking. This figure was later corrected to 23-27% ¹¹; however, more recent studies have not validated this association. In addition to renal and urinary tract malformations, supernumerary nipples have also been reported in association with solid organ malignancies such as renal adenocarcinoma, testicular cancer, prostate cancer, and urinary bladder carcinoma.

Supernumerary nipple clinical features

A supernumerary nipple is present at birth. It often appears similar to a congenital organoid or melanocytic nevus. Most supernumerary nipples are much smaller than the normal areola and nipple. They may be solitary or multiple, arising on one or both sides of the nipple line.

They may be pink or brown, and at least the central nipple is elevated off the skin surface. There may be a central dimple. Supernumerary nipples may develop prominent hair at puberty.

If the supernumerary nipple contains glandular tissue, it can enlarge during puberty, swell and become tender pre-menstrually, and undergo lactation.

Supernumerary nipple diagnosis

A clinical classification tool is the Kajava supernumerary nipple classification (1915) ¹².

• Complete supernumerary nipple – Nipple and areola and glandular breast tissue
• Supernumerary nipple – Nipple and glandular tissue (no areola)
• Supernumerary nipple – Areola and glandular tissue (no nipple)
• Aberrant glandular tissue only
• Supernumerary nipple – Nipple and areola and pseudomamma (fat tissue that replaces the glandular tissue)
• Supernumerary nipple – Nipple only (the most common supernumerary nipple)
• Supernumerary nipple – Areola only (polythelia areolaris)
• Patch of hair only (polythelia pilosa)

Although this classification is clear, encountering interchangeable terms and misnomers when dealing with the supernumerary nipple complex is not surprising due to variability in morphologic patterns.

The paucity of descriptions of supernumerary nipples in medical writings is probably due to its relatively minor clinical significance. The occurrence of supernumerary nipples has been documented since Roman times and featured in legends and ethnic mythology prior to that time. Supernumerary nipples, and particularly polymastia, were attributed to increased femininity and fertility. Ancient artists depicted the goddess of Artemis of Ephesus and the Phoenician goddess of fertility, Astrate, like other ancient deities, as having row upon row of breasts on their chests ¹³. Anne Boleyn, the wife of King Henry VIII, was known to have a third breast. Supernumerary nipples in men were a sign of virility and endowed them with divine powers. Nowadays, film stars expose their supernumerary nipples in the cinema with this same effect ¹³.

The first medical report dates back to 1878 when Leichtenstern estimated the prevalence of supernumerary nipples to be 1 in 500 (0.2%) ¹⁴. In recent years, supernumerary nipples and their association with other congenital anomalies and malignancies has been a topic of considerable debate.

Histology provides definitive diagnosis, as it often resembles the normal nipple.

• Epidermal thickening
• Mild papillomatosis and basal hyperpigmentation
• Pilosebaceous structures
• Smooth muscle
• Breast ducts
• Sometimes presence of underlying breast tissue

Supernumerary nipple treatment

Usually no treatment is required. Surgical removal can be considered for cosmetic purposes or if there is discomfort from lactation or tenderness.

Supernumerary nipples can undergo similar diseases to normal breast tissue. There are reported cases of supernumerary nipples developing:

• Fibroadenoma
• Adenoma
• Cyst
• Abscess
• Mastitis
• Breast cancer

Supernumerary nipple prognosis

Most isolated supernumerary nipples persist without complication. Ectopic breast tissue can be associated with the same inflammatory and neoplastic conditions that affect normal breast tissue. Ectopic breast tissue does not have an increased malignant potential compared with normal breast tissue.

References

1. Goldschmidt E, Jacobsen N. Epibulbar lipodermoids, preauricular appendages and polythelia in four generations: a new hereditary syndrome?. Ophthalmic Genet. 2010 Jun. 31(2):81-3.
2. Smith DW. Comment on association of supernumerary nipples with other anomalies. Oska FA, Stockman JA III, eds. Year Book of Pediatrics. Chicago, Ill: YB Medical Publishers; 1981. 437.
3. Rahbar F. Clinical significance of supernumerary nipples in black neonates. Clin Pediatr (Phila). 1982 Jan. 21(1):46-7.
4. Jaber L, Merlob P. The prevalence of supernumerary nipples in Arab infants and children. Eur J Pediatr. 1988 May. 147(4):443.
5. Casey HD, Chasan PE, Chick LR. Familial polythelia without associated anomalies. Ann Plast Surg. 1996 Jan. 36(1):101-4.
6. Supernumerary nipple. https://emedicine.medscape.com/article/1117825-overview
7. Supernumerary nipples. https://medlineplus.gov/ency/article/003110.htm
8. Toumbis-Ioannou E, Cohen PR. Familial polythelia. J Am Acad Dermatol. 1994 Apr. 30(4):667-8.
9. Aslan D, Gürsel T, Kaya Z. Supernumerary nipples in children with hematologic disorders. Pediatr Hematol Oncol. 2004 Jul-Aug. 21(5):461-3.
10. Méhes K. Association of supernumerary nipples with other anomalies. J Pediatr. 1979 Aug. 95(2):274-5.
11. Varsano IB, Jaber L, Garty BZ, Mukamel MM, Grünebaum M. Urinary tract abnormalities in children with supernumerary nipples. Pediatrics. 1984 Jan. 73(1):103-5.
12. De Cholnoky T. Supernumerary breast. Arch Surg. 1939. 39:926-41.
13. Grossl NA. Supernumerary breast tissue: historical perspectives and clinical features. South Med J. 2000 Jan. 93(1):29-32.
14. Leichtenstern D. Uber das Vorkommen und Bedeutung Supernumerarer (accessorischer ) Bruste und Brustwarzen. Arch Pathol Anat Physiol Klin Med. 1878. 73:222.