Shortly after I purchased my adult Jackson's cham, a bump formed on the base of his tail. I took him to a vet, they said "abscess" and had no questions about it. Took him to another vet for a second opinion (in which we did blood tests, x-rays, culture) and she said it was no abscess, but a growth. He also had a small bump forming on his upper shoulder, next to and behind his tongue, that was just a little discolored-pink area among his green.
When I had him go forward with the surgery, the vet (did her homework on chameleons but wasn't too experienced to begin with) removed the bump on the base of his tail successfully. Not an abscess, just a growth. Not sure of cause to this day.
However, the bump that was below his skin that just caused the little discoloring, above his shoulder, she said she tried to remove but found out that it was just "hardened skin" and couldn't be removed. Nowadays the bump is a bit bigger but looks to not be affecting his life or growing. I have decided not to get it removed if it seems as though it is not hurting him, the vet visits and antibiotics and painkillers were just so stressful for my Jackson's and I don't want to put him through it again if we can avoid it.
If it is absolutely needed, I will do it. Though he is an adult and seems to be doing just fine. His appetite is always hardy and he drinks regularly, has no problems.
Hope you can figure it out! If the vet is certain they can remove it, I would go through with it. Above the spine being a rough area to operate on, my vet said it was risky. Though he pulled through just fine and is all healed to this day!