Oh my, I am familiar with hematomas & there have been some cases like that here on the boards.
Did he previously hurt himself by falling or something of that nature to have caused that?
I am glad though it was not a tumor! Hopefully it will gradually recede & get smaller. I am happy it doesn't bother him & he is eating well & basking.
Thanks for the update on him.
I'm not sure how it happened, it could be genetic apparently, if that's the case he could've landed awkwardly when catching a locust which would've ruptured an already weak vein. He loves climbing though, so he may have fallen, although I don't really see him fall as he is pretty strong. I don't really want to discourage him from climbing because it keeps him active and healthy (or perhaps not if this is a consequence!) I guess I'll just have to keep an eye on him when he tries to climb something.