I have had a tummy tuck approx. 3 years ago and have developed hard lump and constant pain.

I am sorry that you are having this pain. I would recommend that you return and talk with your plastic surgeon. Pain and a hard lump three years after surgery is unusual and can be caused by several things including a hernia. The only way to determine what is causing the problem is a physical exam and possible medical imaging. Good luck and I hope that you feel better.

While there are a number of potential diagnosis for this problem, assuming that you have had no intra-abdominal operations (C-section, hysterectomy, colon resection, etc.), the chances that this represents a hernia are low. I think that the most likely cause is an area of compromised fat that has died due to changes in blood supply and is causing a localize inflammatory reaction. It is also possible that you have a persistent suture that never absorbed and can cause a similar foreign body reaction. Finally, some women present with similar symptoms along a c-section scar (which may have been converted to your tummy tuck scar) and the diagnosis can be a seeding of endometrial tissue in the abdominal wall that is firm and painful particularly during menstruation. Any of these problems are fairly easy to fix with surgery. I would recommend discussing your case with a board certified plastic surgeon, preferably the one who performed your original surgery if possible as he/she has the best understanding of your case.

Tummy tuck changes the blood supply to the skin and fat of the abdomen after surgery.  Sometimes there can be an area of fat that loses its blood supply.  This is called fat necrosis.  This can result in a hard lump that can sometimes be painful.  Since this has not improved over the last 3 years, then I would recommend excising the hard lump.  This will usually relieve the pain that you are having.