Education And Debate

ABC of Breast Diseases: Congenital Problems and Aberrations of Normal Breast Development and Involution

BMJ 1994; 309 doi: (Published 24 September 1994) Cite this as: BMJ 1994;309:797
  1. J M Dixon,
  2. R E Mansel

    Congenital abnormalities Extra nipples and breasts

    Between 1% and 5% of men and women have supernumerary or accessory nipples or, less frequently, supernumerary or accessory breasts. These usually develop along the milk line: the most common site for accessory nipples is just below the normal breast, and the most common site for accessory breast tissue is the lower axilla. Accessory breasts below the umbilicus are extremely rare. Extra breasts or nipples rarely require treatment unless unsightly, although they are subject to the same diseases as normal breasts and nipples.

    Usual sites of accessory nipples and breasts along milk lines.

    Patients with an accessory nipple (left) and bilateral accessory breasts (right).

    Absence or hypoplasia of the breast

    One breast can be absent or hypoplastic, usually in association with defects in pectoral muscle. Some degree of breast asymmetry is usual, and the left breast is more commonly larger than is the right. True breast asymmetry can be treated by augmentation of the smaller breast, reduction or elevation of the larger breast, or a combination of procedures.

    Left breast hypoplasia. Breast asymmetry.

    Breast development and involution

    The breast is identical in boys and girls until puberty. Growth begins at about the age of 10 and may initially be asymmetrical: a unilateral breast lump in a 9-10 year old girl is invariably developing breast, and biopsy specimens should not be taken from girls of this age as they can damage the breast bud. The functional unit of the breast is the terminal duct lobular unit or lobule, which drains via a branching duct system to the nipple. The duct system does not run in a truly radial manner, and the breast is not separated into easily defined segments. The lobules and ducts - the glandular tissue - are supported by fibrous tissue - the stroma. Most benign breast conditions and almost all breast cancers arise within the terminal duct lobular …

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