Is this axillary breast tissue or arm fat? (Photo)

Axillary breast tissue is fairly common, it is a combination of fatty and glandular breast tissue. Axillary breast tissue is usually in the armpit, in front of the armpit/ anterior, or below the armpit toward the chest. Excess tissue beyond the armpit crease towards the arm is usually upper arm adipose/ fat.
Treatment options include direct excision and liposuction.

Axila bulges because of the combination of excesses: breast tissue, fat and saggy skin.
If you get removed fat and breast tissue only, the saggy skin will become more obvious and the area will not be tighter. So you need the combination of procedures: removal of the breast tissue, liposuction and skin tightening. Also is extremely important your BMI is below 28-29 because the excess of that area (fat) is genetically influenced, so you must get it fixed with surgery and maintain it with weight control.
Dr. Cárdenas

Dear Awesome943059,
it is hard to tell for sure without an examination. If you are considering surgery, I would suggest you consult a board-certified plastic surgeon. Only after a thorough examination, you will get more information and recommendations.
Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery

An examination is needed to see how much is fat that can be treated with liposuction, and how much is actual breast tissue which cannot be removed with liposuction. Just based on your photos, I suspect most is fat.

Axillary breast tissue is unique because it is a combination of fatty tissue and glandular tissue. Common sites can reach up into the armpit area. Tissue in the upper portion of the arms is typically fatty tissue.

Axillary breast tissue is a common condition. It varies a bit from person to person but this tissue tends to be very fatty and not have the same firm consistency that glandular breasted tissue has in the center of the breast.
Usually the change in contour is related to your laxative breast tissue and fat. The tissue itself cans to have enough fat and be soft enough that it can generally be effectively removed using liposuction. This is not true for firm breast tissue in the center of the breast.
Liposuction however does not deal with the skin laxity which typically contributed significantly to the contour and only removing subcutaneous tissues done with either open surgery or with Liposuction and not addressing the skin laxity typically only leads to a partial improvement.
Most people benefit from having some axillary skin removed in conjunction and for that reason it’s sometimes better to do these as open procedures(not Liposuction).
Each plastic surgery will have their own opinion view and technique based on their experience training and personal philosophy.
Generally speaking for a cases who have significant fullness in the Ariel failure to address some of the skin laxity with some skin reduction often leads to sub optimal outcomes.
For some patients having skin redundancy is undesirable while for others it doesn’t bother them.
Some people are highly adverse to having visible scars while others aren’t bothered by it.
Breast tissue in the armpit usually follows a certain anatomic course and the tissue is often called the axillary tail of Spence. Tissue and surrounding areas are most likely 100% fat and the tissue that follows the typical fourth axillary breast issue is typically fatty breast tissue that looks more like fat than breast tissue when removed.
Best,
Mats Hagstrom MD