Dermatologist I guess. For a growth like that they'll probably want to cook it with an electric needle. Once they get to a certain size and depth the liquid nitrogen method doesn't work so well. Doc may want to cut it out too.
A friend and I (when we were teens) were chasing barracuda on the flats in the Florida Keys. We walked around for hours in thigh deep water sight casting to small groups of cuda with tube lures, and because they were biting we stayed out for hours. A some point my buddy decided to kick of his Tevas and go barefoot. No coral there, just sand, muck, and turtle grass so no big deal right?
That evening he was losing his mind his feet itched so bad, we all kinda laughed it off. Next morning things were decidedly less funny! The bottom of his right foot was almost completely covered in what looked like black warts embedded into white, gross looking skin, as if he has spent the night soaking in a bathtub. The left foot was the same but only about %40 coverage. His feet looked like a cross between brain coral and frog eggs, one of the nastiest things I've ever seen.
Took him to a doctor and they were baffled, said it must have been some kind of organism or parasite that burrowed in and caused the reaction.
They gave him a valium, had him lay down on his stomach, and proceeded to stick every single one of those wart things with a syringe-like tool that had voltage running thru it. Poor guy endured that for hours, made the office smell like BBQ'd ass, and he couldn't walk right for days. The amount of mass that ended up coming off of his feet was nothing short of amazing.
Whatever happens be glad you only have to worry about one of those things!