It is possible to have axillary breast. If it is breast tissue it will likely change in size with the menstrual cycle and pregnancy.
It is actually very common to have breast tissue that extends into the armpit (axilla) and most women notice it for the first time during pregnancy. It can definitely be removed at the time of any breast surgery and will not restrict upper arm mobility or lymphatics. Your plastic surgeon likely feels very comfortable managing this issue. Best of luck.
Thank you for the question and picture. You are correct in that this area of fullness tends to consist of mainly breast tissue. In my experience, it is best treated ( for most patients) with direct excision of the “excess” skin and breast tissue. Liposuction surgery alone will likely not be as effective and/or may leave you with continued excess/irregular skin. Yes, this area can be excised at the time of breast augmentation surgery.Placement of the incision line in the hair bearing axillary area is one of the keys to success; keeping the resulting scar as hidden as possible is important to most patients.I hope this helps.