Is This a Sign of Necrosis? (photo)

This is not necrosis. The skin is still irritable from surgery. For these issues I typically recommend Aquaphor ointment and bandaging to prevent rubbing on the area. Soft bra also may be good idea. If this does not heal within a week or two, you should return to your plastic surgeon for assessment.

Most likely a dissolvable stitch worked it's way out and has left you with a small hole. I recommend keeping the area clean and covered. You might want to see your surgeon and let him/her check your breast.

No this is not tissue necrosis.   It is most likely a dissolvable deep stitch, which has made its way to the surface.   It could also be due to friction/rubbing on a fresh scar.    I would recommend visit to your plastic surgeon to rule out a stitch problem.   Also, I would use a nonadherent dressing with bactroban over the opening.

Dr. Gill