Apparent sore / green iguana

I have owned my iguana for about seven years...it was abandoned at my place of work when it was about four years old. It is reasonably healthy
and has plenty of space and sunlight and may roam freely if he wants on a sun-lite area of the house. Recently I have noticed on the bottom of a rib,
more on his side than underneath on his belly, what appears to be a cyst..he is somewhat sensitive when you touch it. It is not oozing or anything but
appears almost like a wart but distinctly raised, sort of a distinct bump.
His appetite is good..eats fresh food almost daily. Has anyone out there had
such an occurrence?

Hello,

What type of UVB lighting are you providing? Do you supplement calcium several times a week, with D3 as well?
Does he go outside for his sunlight, or does he get it through a window? Keep in mind, UVB's from sunlight will not penetrate through glass. If he gets some sunlight through a small screen, that will filter out quite a bit of the UVB so he still needs a good UVB light on him as well. They have large UVB requirements.
Usually, cysts, or growths occuring on ribs are calcium related, most of the time. This is from being deficient in calcium.
Has he ever seen a vet for x-rays or gotten any blood work to test his calcium levels?

Tracie