Axillary breast tissue refers to the presence of breast tissue in the armpit, or axilla, area. This condition is relatively common, affecting approximately 2% to 6% of women and 1% to 3% of men. While often benign, its presence can lead to concerns about its appearance or potential discomfort. This article explores the underlying reasons for axillary breast tissue formation and its implications.
Understanding Axillary Breast Tissue
Axillary breast tissue, also known as accessory breast or polymastia, is breast tissue located outside the typical breast region. It is distinct from simple fat pads or swollen lymph nodes, as it contains components similar to normal breast tissue, including glandular tissue, ducts, and fat. Unlike general armpit fat, which is solely adipose tissue, axillary breast tissue is capable of responding to hormonal changes.
Embryological Development
The existence of axillary breast tissue stems from human embryological development. During the fourth to sixth week of gestation, two bilateral thickenings of ectoderm, known as the “milk lines” or mammary ridges, form along the ventral surface of the embryo. These ridges extend from the armpit area down to the groin. Normally, most of this milk line regresses, with only a small segment persisting to form the primary breasts in the chest region. Axillary breast tissue develops when portions of this embryonic tissue fail to disappear completely, making it a congenital condition present from birth, though it may become noticeable later in life.
Physiological Triggers for Growth
While axillary breast tissue is present from birth due to embryological development, its growth and prominence are often triggered by hormonal fluctuations. Like normal breast tissue, accessory breast tissue is responsive to hormones such as estrogen, progesterone, and prolactin.
Puberty is one such period when hormonal changes can stimulate its growth, making it more noticeable. Pregnancy and lactation are other triggers, as the accessory tissue can swell, become tender, and even produce milk, mirroring the changes in the main breasts. Hormonal therapies, including birth control or hormone replacement therapy, can also influence its size and sensitivity. Additionally, significant weight gain can make it more prominent due to increased fat deposition within and around the accessory tissue.
Common Concerns and Management
Individuals with axillary breast tissue may experience various symptoms, including tenderness, swelling, or pain, particularly during hormonal changes like menstruation or pregnancy. It can also lead to cosmetic concerns due to visible bulging in the armpit area, which may affect clothing choices or self-confidence. In some cases, the presence of this tissue can restrict arm movement or cause irritation from clothing.
Diagnosis
Diagnosis typically involves a physical examination, where a healthcare provider assesses the lump or swelling. Imaging techniques such as ultrasound or mammography may be used to confirm the presence of glandular tissue and differentiate it from other conditions like fat deposits or lymph nodes. Rarely, a biopsy might be performed if there is a suspicion of abnormal changes.
Management
Management options vary based on symptoms and concerns. If asymptomatic, observation may be sufficient. For discomfort, cosmetic concerns, or suspicion of pathology, surgical removal, often through liposuction or excision, can be considered. Axillary breast tissue can be susceptible to the same conditions as normal breast tissue, including benign lumps and, rarely, cancer. Therefore, medical evaluation of any changes is important.