The Axilla is the medical term for the under-arm area. Every woman has breast glandular tissue in the axilla as well as many lymph nodes. As a matter of fact, the collection of breast tissue that is present in every woman's axilla is called the Axillary Tail of Spence and is considered a normal anatomical structure.
It is not normal for the glandular tissue in the Axillary Tail of Spence to be of such a large quantity that it is both visible and easily palpable (palpable means that you can easily feel it with your finger). This, however, is a common developmental abnormality.
Another reason why breast glands in the axilla region can become visible is due to the hormonal stimulation effects of pregnancy. It is fairly common for women who are pregnant to develop a prominent enlargement of the axillary glandular tissue. Normally this tissue goes back down to a normal size after delivery of the child.
In cases where this enlarged axillary breast tissue persists, a safe and conservative removal of the abnormally enlarged tissue is performed through a small incision hidden in the axilla.
Below are several views of a typical case of axillary breast tissue enlargement that persisted after delivery of a healthy baby. The patient will undergo removal of the excess once she has completed breast feeding, or once she is fully recovered from the physical and psychological demands and stress of childbirth (if she does not intend to breast feed).