From the Guidelines
Yes, breast tissue can be present in the axillae (armpits). This is known as accessory breast tissue or axillary breast tissue and occurs in approximately 2-6% of women 1. During embryonic development, breast tissue forms along milk lines that extend from the armpit to the groin. Normally, most of this tissue regresses, leaving only the breast tissue on the chest. However, sometimes this regression is incomplete, resulting in accessory breast tissue in locations along these milk lines, with the axilla being the most common site.
Key Points to Consider
- This tissue responds to hormonal changes just like normal breast tissue, so it may become more noticeable or tender during puberty, pregnancy, or menstruation 1.
- While usually harmless, axillary breast tissue can develop the same conditions that affect normal breast tissue, including cysts, pain, and rarely, cancer 1.
- If a suspicious finding or mass is identified in the axilla, ultrasound (US)-guided biopsy can be performed for definitive diagnosis, even if the malignancy rate may be low in a woman with a palpable axillary mass and no other signs of malignancy 1.
Recommendations for Evaluation
- If you notice unusual swelling or lumps in your armpit, it's advisable to have it evaluated by a healthcare provider, especially if there are changes in size, texture, or if it becomes painful 1.
- Diagnostic mammogram and/or digital breast tomosynthesis (DBT) may be used to evaluate the breast for underlying lesions in the setting of patients presenting with axillary lymphadenopathy 1.
From the Research
Presence of Breast Tissue in Axillae
- Breast tissue can be present in the axillae (armpits), as reported in several studies 2, 3, 4, 5, 6.
- This ectopic or accessory breast tissue is most commonly located in the axilla, though it may be present anywhere along the milk line 2.
- The development of this tissue is hormone-dependent, similar to normal breast tissue 2.
Incidence and Characteristics
- Accessory axillary breast tissue is present in approximately 2% to 6% of women 4.
- This tissue can undergo monthly premenstrual changes, such as tenderness and swelling, and can be cosmetically unsightly 4.
- Ectopic breast tissue can develop along the mammary ridge from the axilla to the groin, and the most common site is the axillae 3.
Pathologies and Treatment
- Ectopic breast tissue can undergo the same physiological and pathological processes as the normally located breast, including the development of fibroadenoma 6 and invasive ductal carcinoma 3.
- Surgical removal of accessory axillary breast tissue is often recommended to address cosmetic concerns and minimize cancer risks 4, 5.
- Identification and distinction of ectopic breast tissue from other breast pathologies, both benign and malignant, is essential to provide appropriate treatment and management 2.