Supernumerary nipples are common minor congenital malformations that consist of nipples and/or related tissue in addition to the nipples normally appearing on the chest. Supernumerary nipples are located along the embryonic milk lines. Ectopic supernumerary nipples are found beyond the embryonic milk lines. The embryonic milk line is the line of potentially appearing breast tissue as observed in many mammals. In humans, the embryonic milk line extends bilaterally from a point slightly beyond the axillae on the arms, down the chest and the abdomen toward the groin. It is generally thought to end at the proximal inner sides of the thighs, although supernumerary nipples have been described on the foot. [1] Supernumerary nipples can appear complete with breast tissue and ducts and are then referred to as polymastia, or they can appear partially with either of the tissues involved.

The classification established by Kajava in 1915 remains valid [2] :

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. [3] 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. [3]

The first medical report dates back to 1878 when Leichtenstern estimated the prevalence of supernumerary nipples to be 1 in 500 (0.2%). [4] In recent years, supernumerary nipples and their association with other congenital anomalies and malignancies has been a topic of considerable debate.

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 [5] ; ectodermal dysplasia; Kaufman-McKusick syndrome; Char syndrome; Simpson-Golabi-Behmel syndrome; and epibulbar lipodermoids associated with preauricular appendages syndrome. [6] 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

Publications concerning renal and urinary tract involvement in the presence of supernumerary nipple

In 1979, Méhes drew attention to the association of supernumerary nipples and other anomalies. [7] The claim that 40% of supernumerary nipples investigated also had renal involvement was striking. This figure was later corrected to 23-27% [8, 9] ; 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.

Claiming close association are as follows:

Méhes, 1979 [7]

Goedert et al, 1981 [10]

Méhes, 1983 [8]

Kahn and Wagner, 1982 [11]

Varsano et al, 1984 [9]

Meggyessy and Méhes, 1984 [12]

Hersch et al, 1987 [13]

Méhes and Pinter, 1990 [14]

Leung and Robson, 1990 [15]

Urbini and Betti, 1996 [16]

Brown and Schwartz, 2004 [17]

Ferrara et al, 2009 [18]

Grimshaw et al, 2013 [19]

Denying support for association are as follows:

Smith, 1981 [20]

Rahbar, 1982 [21]

Mimouni et al, 1983 [22]

Robertson et al, 1986 [23]

Kenney et al, 1987 [24]

Hoyme, 1987 [25]

Bortz et al, 1989 [26]

Armoni et al, 1992 [27]

Jójárt and Seres, 1994 [28]

Casey et al, 1996 [29]

Schmidt, 1998 [30]

Grotto et al, 2001 [31]

The Medscape article Disorders of the Breast may be of interest.