Fat transfer has become a very common procedure to surgically enhance any part of the body, but you need to understand that even though fat is useful to augment parts of the body, it does not behave like an implant. For example, if you put in a breast implant, you can rest assured that the volume is not going to change significantly over time, unless you get soft tissue atrophy secondary to the implant interactions with the surrounding tissue. However, fat is very different than a static implant. Fat is a dynamic implant. This means that the fat is alive, and augmenting any part of the body with fat can be unpredictable if the proper techniques are not used.One of the complications that can occur from the fat transfer procedure is fat necrosis, which means that some of the fat that was injected dies. During a fat transfer, some of the fat may get reabsorbed, causing absolutely no consequences except that the area gets smaller. However, in certain circumstances, the fat actually dies and forms a layer of dead fat and scar formation. Typically, this occurs when high-volume fat transfers are performed, particularly in the buttock area. So, you need to be careful what you wish for. People want to have as much fat injected into their buttocks as they can, thinking that all the fat will survive and no complications will occur. The more fat you put in your buttocks, the more complications you may have. The more fat you put in the buttocks, the higher the chance that some areas in the buttocks will develop fat necrosis.Fat necrosis can cause lumps and bumps, areas of hardening, and pain in the specific area. Most of the time, this does not cause any issues, but if the patient is having pain, there are certain things that we can do, like injections of Kenalog, which is an anti-inflammatory agent. Rarely, a revision surgery needs to be performed to actually remove the area of fat necrosis.Fat necrosis is not as uncommon as most people think. As a matter of fact, most fat necrosis is asymptomatic, and this is the reason that most people do not even talk about it. If you develop an area of hardening, even if it is not causing any issue, most likely, you have fat necrosis. The treatment is to do absolutely nothing unless the area becomes symptomatic. If it becomes symptomatic, I will offer you medical or surgical intervention.