Can scar tissue/suture granuloma form internally under the nipple after a breast reduction with new implants?

Small lumps are not uncommon after a breast reduction. Common causes include scar tissue or fat necrosis. A more definitive diagnosis would require a physical examination. Discuss your concerns with your surgeon.

Dear Straightforward494999,
I understand your concern. generally speaking, scar tissue forms in place if injury so it can form under the nipple. However, without a proper assessment, it would be difficult to determine what went wrong. It is best that you visit your plastic surgeon for further assessment or ask for a second opinion. Only after a thorough examination, you can get proper recommendations and advice.
Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery

It could be a stitch, but most used are dissolvable, or it could have been an area of fat necrosis that developed scar tissue. Please discuss this with your surgeon.

It is impossible to accurately answer your question without a proper physical exam. There is not enough information to give you a proper response.
Scar tissue may form anywhere: thick or thin, painful or painless. Most surgeons use dissolving sutures when performing a lollipop mastopexy (whereas in a periareolar procedure, a permanent suture may be left in place).
Return to your surgeon for their opinion.
Best wishes.
Dr. Taranow