What is single incision surgery for FTM top surgery, and why would it be used instead of periareolar or keyhole surgery?

There are several methods used which depend upon the patient’s breast or chest #size before surgery. Considerations on the surgical technique to be applied include the #laxity of skin, the #size of the #areola, the amount of #fat and recent weight #gain or weight #loss. The most common procedures which are described include the #periareola, #buttonhole, #double incision, and #anchor patterns. I often use #liposuction along with the double #incision for larger breasts, and, some variation for smaller breasts; depending upon the position of the areola. The female breast nipple and areola are often centered on the breast. However, the nipple and areola are lower and closer to the outside edge of the #pectoralis muscle in the male patient. Shaping the side of the chest may also be required and can be performed with #suctioning; along with contouring of the muscle, as noted above, to provide the best definition for the chest. Being each person varies, it’s important to be realistic about your goals and what is achievable. It's best to consult with your board-certified plastic surgeon about your concerns and to confirm if FTM Top is in your best interests.

Thanks for your question.  I agree with the below consultants.  I do not recommend an incision in the sternal area.  For someone like your son, I would usually use a periareolar incision, which I think heals very well.  Best Regards.

I share your confusion. Based on the information provided, the only thing that is clear is that you (and apparently the prospective patient) do not have a clear understanding of the surgical plan or the anticipated permanent scars. I hate this type of answer, but I can only recommend that you have another discussion with your surgeon.
Otherwise, I can guess that what may have been meant was that your transgender son has areolas that are "too small" for the anticipated subcutaneous mastectomies, so the surgeon is suggesting a (larger?) incision (between the breasts?) to allow the work to be done.In twenty five years of doing this kind of surgery, I've not encountered areolas too small to allow performance of mastectomies for the appropriately-small breast tissue in transgender patients who qualify for this procedure anatomically. That's the whole idea of "keyhole" mastectomies. Please talk to your surgeon, and if answers are not suitably forthcoming, consider switching to a different surgeon experienced in transgender mastectomies. Best wishes! Dr.Tholen

Typically the goal of this surgery is to reduce the amount of breast tissue AND to make scars as invisible as possible. While this surgery is considered "functional," aesthetics matter just as much, as large visible scars can lead to poor body image, wanting to cover up, etc. For smaller breasts, I would advise removal of the breast tissue through an incision hidden in the areola +/- some liposuction to remove any additional fullness or tissue that can't be reached through the keyhole incision. 

In general, a periareolar incision can be used to remove small amounts of breast tissue.  Larger breasts require a double incision for better cosmetic results.  I have not heard of a "simple incision" for FTM surgery.