Breast Reduction - hole developed. Is this a splitting suture? (photos)

It is very likely that's what you have shown is a spitting stitch and this is very common in breast reduction surgery. To close this type of incision many buried stitches are placed to reapproximate to take tension off the closure. Sometimes one or two or more stitches will spit and desist treated wood local care using Neosporin twice a day. 

Suture issue, fat necrosis, or both. See you surgeon for in person care ASAP.........................

Breast reduction surgery often requires the placement of hundreds of buried stitches in order to align the tissues to achieve smooth contours.  These sutures will slowly dissolve over time as they are being broken down by the body's immune system.  Sometimes the body will "reject" the suture, and spit it out of the skin similar to what happens with a splinter in the skin.  This is known as a spitting stitch or suture.  If there is inflammation and pus, this is known as a stitch abscess.  Most surgeons recommend cleansing the area with mild soap and water, and then apply antibiotic ointment to the wound. The area will typically close over several days.  Persistence of the opening suggests a retained suture, and will need to be addressed by your surgeon.I would recommend reporting the problem to your surgeon, so he or she may follow up on the issue with you.Good luck with the rest of your recovery!