DX is having day surgery on January 4th.
We saw the second ENT on Wednesday of this week, and he wants to move quickly. He says that the most common condition like this in 3 year olds is a cholesteotoma (the benign cyst thingy), but he's not sure that this is what we're dealing with, as there is some vascularization of the growth apparent on the CT scan.
So, he needs to have a "look-see" and, hopefully, can remove whatever it is. Cross your fingers for us that this turns out to be nothing unexpected.