What Is The Red And Bruised Hard Band Around My Left Leg?

I have had a hard band around my left leg just below the calf since 2007. I have been to 5 different doctors and had MRI's, blood test, etc. The area affected appear slightly red to bruised looking. It has recently began to itch and have small bumps that are fluid filled. My leg appears bowed where the band is when I stand with my legs together. It concerns me, but no one has a clue what it is.