Is this an infection after breast reduction?

Most infections following breast reduction surgery occur in the immediate post-operative period.  Occasionally infections occur late in the patient’s recovery and this is usually related to a stitch abscess.
This problem occurs when infection develops around one of the absorbable internal sutures that are used during breast reduction surgery.  This can result in a marble sized abscess or granuloma that requires drainage and treatment with antibiotics.  This is a relatively simple problem to deal with if treated early.  If diagnosis and treatment are delayed, then more significant problems can result.
This problem requires follow up with your surgeon.  With appropriate care, this should represent a minor setback with no long term consequences.

Thank you for the question  and the precise description of your problem.

The two most common culprits that would explain your situation are suture related infections and/or fat necrosis.  Since  you have been treated you should be fine.

Best wishes.

Great question. It is very odd to have the presentation you had, as typically an infection etc. is unlikely to present that far out from surgery. Most likely, since it is your incision, is a reaction to one of the sutures that your body had an inflammatory response to. This can lead to an infection or simply be inflammation. It's possible you had it for a while and it finally erupted through the skin just recently. Either way it should get better after drainage and go away.
-Dr. David Mattos, New York Plastic Surgical Group