I'm 34 yrs old and I've a depression in my left thigh. It's about the size of my little finger. How can I get rid of it? (Photo)

You may consider a scar revision to excise the indent, but the trade off would be a linear scar, bigger than the dent in your thigh.  The scar may be more subtle than the dent, it depends on whether or not that would bother you.  Possibly liposuction of a small area & fat injections to fill in the indent. Fat grafting can survive permanently, however there's always a chance some of it can be absorbed by the body.  Rest assured you do have options to remove or improve this dent that bothers you.Best of Luck.  

It is not unusual to have a dent result from multiple injections in the same area, especially in a baby or young child.  The injections can result in bruising and fat necrosis (death of the fat cells in an area).  This can lead to a depressed area where the fat failed to grow normally.  The best option will be a small surgery to free the scarred skin and perform a fat graft or free fat transfer to the depression.  The result may not perfectly fill the depression, but it should be improved significantly.  Best wishes, Dr. Lepore.