Fat Grafting Gone Wrong/complications. Fat Transfer to Butt - My Story? (photo)

This looks like an infection of the area. You need to have it opened up and drained surgically. Please follow up with your doctor as these issues require the attention of a plastic surgeon.

   Although I have been fortunate not to have such an occurrence, I think that there is a possibility of this happening and is likely not technique dependent.  Sometimes less than optimal outcomes happen to good patients and good surgeons alike.  I would continue to follow closely with your plastic surgeon.  Kenneth Hughes, MD Los Angeles, CA

This is an uncommon outcome from fat injections to the buttocks but is most likely the result of such high fat volumes placed. (over 1000ccs per buttock)  As you have mentioned, this is fat necrosis in which the risk of occurrence increases when the volume of fat is so high and large segments of the injected fat can not get nourished and die. When this happens it will do so closest to the skin which is furtherest away from a good blood supply.