Supernumerary breasts

Supernumerary breasts, also known as polymastia or accessory breasts, is a congenital condition in which one or more additional breast tissues develop along the embryonic mammary ridge (milk line), which extends from the axilla (armpit) to the groin on both sides of the body. This condition results from incomplete regression of the mammary ridge during fetal development. The extra breast tissue may range from a small amount of glandular tissue without a visible nipple to a fully formed accessory breast with a nipple and areola. The most common location for supernumerary breasts is the axillary (underarm) region or just below the normal breast on the chest or abdomen. The condition affects the integumentary system and, in some cases, the underlying soft tissues of the chest or abdominal wall. Supernumerary breasts are usually present from birth but may become more noticeable during puberty, pregnancy, or lactation, when hormonal changes cause the accessory tissue to enlarge, become tender, or even produce milk. In most cases, the condition is benign and asymptomatic, though it can cause cosmetic concerns, discomfort, or psychological distress. Importantly, accessory breast tissue is subject to the same pathological conditions as normal breast tissue, including fibroadenomas, cysts, and, rarely, breast carcinoma. Therefore, clinical surveillance may be recommended, particularly if the tissue is glandular. Treatment is generally not required unless the individual experiences symptoms, cosmetic concerns, or complications. Surgical excision is the standard treatment when intervention is desired, and it is typically curative. Supernumerary breasts can occur as an isolated finding or, less commonly, in association with other congenital anomalies, including renal or urinary tract malformations, though this association remains debated in the literature.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

Common questions about Supernumerary breasts