I had Restylane defyne injected in my chin. I grew this fatty patch on one side..is this swelling or filler?

You do not mention how long ago you had your treatment. There can be some swelling after injections, which could affect your ability to see your final results right away. If it has been at least two weeks since your procedure, I recommend scheduling a follow-up with your injector. It may be that you need to have a bit of the filler dissolved on one side to create a more symmetrical appearance. Since Defyne is a hyaluronic acid filler, this is a simple process that requires injections of hyaluronidase to dissolve a portion of the filler. Always work with a very experienced, qualified injector for these treatments to ensure the best possible results.

Without knowing the techniques used by your injector and not having Before and After photos, it would be difficult to determine what had happened with your results. Restylane Defyne is a great, flexible product that can be used in many areas of the face, including jawline and chin. For more structure in the jawline and chin, there are other stronger products that can uphold this look. I recommend that you follow up with an experienced and knowledgeable injector. 
Best, 
Dr. Anil Shah

I use Defyne for these areas on a daily basis. If you feel that the chin is asymmetric, go back to your injector and see if it needs dissolving or more added. Without pictures I'm unable to assist you further. Defyne has a mid-range G' and should do well in areas needing support.