Last Updated: July 18, 2005
|Synonyms and related keywords: accessory nipples, polythelia, SN, polymastia, extra nipples
||Section 1 of 10
|Author: Aryeh Metzker, MD, Consulting Staff, Department of Pediatric Dermatology, Senior Clinical Lecturer, Department of Dermatology, Sourasky Medical Center, Sackler School of Medicine, Tel Aviv University
|Editor(s): Mark A Crowe, MD, Assistant Clinical Instructor, Department of Medicine, Division of Dermatology, University of Washington School of Medicine; Michael J Wells, MD, Associate Professor, Department of Dermatology, Texas Tech University Health Sciences Center; Robert A Schwartz, MD, MPH, Professor and Head of Dermatology, Professor of Medicine, Professor of Pediatrics, Professor of Pathology, Professor of Preventive Medicine and Community Health, UMDNJ-New Jersey Medical School; Glen H Crawford, MD, Assistant Clinical Professor, Department of Dermatology, University of Pennsylvania School of Medicine; Chief, Division of Dermatology, The Pennsylvania Hospital; and Dirk M Elston, MD, Teaching Faculty, Department of Dermatology, Geisinger Medical Center
||Section 2 of 10
Background: Supernumerary nipples (SNs) are a common minor congenital malformation that consists of nipples and/or related tissue in addition to the 2 nipples normally appearing on the chest. SNs are located along the embryonic milk line. Ectopic SNs are found beyond the embryonic milk line. 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, and ends at the proximal inner sides of the thighs. SNs 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 is still valid (De Cholnoky, 1939):
- Complete SN - Nipple and areola and glandular breast tissue
- SN - Nipple and glandular tissue (no areola)
- SN - Areola and glandular tissue (no nipple)
- Aberrant glandular tissue only
- SN - Nipple and areola and pseudomamma (fat tissue that replaces the glandular tissue)
- SN - Nipple only (the most common SN)
- SN - Areola only (polythelia areolaris)
- Patch of hair only (polythelia pilosa)
Although this classification is clear, encountering interchangeable terms and misnomers when dealing with the SN complex is not surprising because of the variability in morphologic patterns.
The paucity of descriptions of SNs in medical writings is probably due to its relatively minor clinical significance. However, the subject of SNs has been very popular in the last 2 decades because of the dilemma of possible associated malformations and diseases. The occurrence of SNs has been documented since Roman times and featured in legends and ethnic mythology prior to that time. SNs, 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 (Grossl, 2000). Anne Boleyn, the wife of King Henry VIII, was known to have a third breast. SNs in men were a sign of virility and endowed them with divine powers. Nowadays, film stars expose their SNs in the cinema with this same effect (Grossl, 2000).
The first medical report dates back to 1878 when Leichtenstern estimated the prevalence of SNs to be 1 in 500 (0.2%) (Leichtenstern, 1878).
Associations with other diseases
SN 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 (Aslan, 2004); ectodermal dysplasia; Kaufman-McKusick syndrome; and Char syndrome. Numerous sporadic publications linked SNs to an association with anomalies or diseases, but such an association is probably only a chance finding.
In 1979, Mehes drew attention to the association of SNs and other anomalies (Mehes, 1979). The claim that 40% of SNs investigated also had renal involvement was striking. This figure was later corrected to 23-27% (Mehes, 1983; Varsano, 1984). The renal involvement was infectious, a malformation, or neoplastic but mainly due to an obstructive disturbance. Other associations of SNs include the following:
- Central nervous system
- Familial alcoholism
- Fetal alcohol syndrome
- Intracranial aneurism
- Neural tube defect
- Developmental delay
- Peptic ulcer
- Pyloric stenosis
- Ears, nose, and throat
- Laryngeal web
- Ear abnormalities
- Hand malformation
- Vertebral anomaly
- Absence of rib
- Coronal suture synostosis
- Scalp defects and microcephaly
- Essential hypertension
- Conduction defect
- Bundle-branch block
- Patent ductus arteriosus
- Congenital heart disease, atrial septic defect, and ventricular septal defect
Publications concerning renal involvement in the presence of SN
In the following decade, numerous publications supported the claim for a close association of SNs and a renal anomaly, but many others could not find evidence to support such an association, which remains controversial.
- Claiming close association
- Mehes, 1979
- Goedert et al, 1981
- Mehes, 1983
- Kahn and Wagner, 1982
- Varsano et al, 1984
- Meggyessy and Mehes, 1984
- Hersch et al, 1987
- Mehes and Pinter, 1990
- Leung and Robson, 1990
- Urbini and Betti, 1996
- Brown and Schwartz, 2004
- Denying support for association
- Smith, 1981
- Rahbar, 1982
- Mimouni et al, 1983
- Robertson et al, 1986
- Kenny et al, 1987
- Hoyme, 1987
- Bortz et al, 1989
- Armoni et al, 1992
- Jojart and Seres, 1994
- Casey et al, 1996
- Schmidt, 1998
- Grotto et al, 2001
Pathophysiology: Saint-Hilaire in 1836 and Darwin in 1871 advanced the concept of development of the human race from primitive animals; thus, they also considered the SN as an atavistic structure deriving from the milk line of mammals. Similarly, ectopic SN found on the vulva may express an atavistic structure because the breasts of dolphins and whales are in that location, or ectopic SN on the back, the scapula, and the shoulder (Newman, 1988; Baruchin, 1981) is reminiscent of the nutria and hutia (rodents) with a similar location of the breasts.
Between the fourth and fifth weeks of embryogenesis, an ectodermal thickening forms symmetrically along the ventral lateral sides of the embryo. This epidermal ridge extends from the axillary region to the inner side of the thigh to form the embryogenic milk (or mammary) line. During the second and third embryogenic months, the glandular elements of the breasts are formed near the fourth and fifth ribs, with regression of the rest of the thickened ectodermal streaks. In the case of failure of a complete regression, some foci may remain to result in a SN. This can develop into a supernumerary complete breast (polymastia) or into any other SN variant according to the Kajava classification.
- Internationally: The prevalence of SNs varies with different reports. The prevalence is 0.22% in a Hungarian population (Mehes, 1979), 1.63% in black American neonates (Rahbar, 1982), 2.5% in Israeli neonates (Mimouni, 1983), 4.7% in Israeli Arabic children (Jaber, 1988), and 5.6% in German children (Schmidt, 1998). These variabilities are attributed at least partially to differences in geographic regions, ethnic groups, and methodology, including methods of physical examination, as well as the age groups participating in the studies.
Sex: The male-to-female ratio differs in various studies, but, most often, the studies show a male predominance as high as 1.7:1.
- Usually, the SN remains undetected or asymptomatic.
- Occasionally, the SN is noticed only when hormonal changes during adolescence, menstruation, or pregnancy cause increased pigmentation, fluctuating swelling, tenderness, or even lactation.
- The SN is often overlooked at the first examination of the neonate. It appears as a small pigmented or pearl-colored mark or as a concave or umbilicated spot. In 75% of patients, it measures no more than 30% of the diameter of the normal nipple (at times no more than 0.2-0.3 cm in diameter). In the other 25% of patients, it is of medium size, as large as 50% of the normal size of the nipple. Rarely, a SN is as large as a normal nipple (Schmidt, 1998). It can be mistaken for many other small lesions, most of them hardly noticeable (see Other Problems to be Considered).
- Most SNs are single, and, when 2 or more (as many as 8) SNs are present, they are distributed bilaterally or unilaterally, symmetrically or not. Most SNs are located below the regular nipple, while approximately 13% appear above it along the milk line (Mimouni, 1983).
- When examining adolescent girls, the normally developed breast may hide the SN. A number of studies have indicated a preponderance of SNs on the right side (Armoni, 1992).
- For easier detection of the SN, a wet gauze pad is passed along the mammary line (milk line) from the axillary region to the upper part of the thigh on each side. This technique is particularly helpful in the dry and desquamating skin of full-term and postterm infants (Mimouni, 1983). When the suggested lesion is concave, folding it between fingers shows a typical wrinkling.
- Approximately 5% of SNs are ectopic, located outside of the milk line, such as on the back (Hanson, 1978), the shoulder (Schewach-Milet, 1976), the limbs, the neck, the face, and the vulva.
Causes: Familial cases were recorded as parent-child transmission, including 1 report of a family who had SNs in 4 successive generations; therefore, autosomal dominant with incomplete expressivity is the accepted transmission of inheritance (Toumbis-Ioannou, 1994).
||Section 4 of 10
Other Problems to be Considered: