Axolotl at pet store

[Kiki]

I was just at a local pet store and saw axolotls for the first time. They were turned in by a customer. I was thinking of realscuing them. They are in a. Set small tank there. My concern is this one has a large black legion on his head. Anyone know what it could be??

 

[Bette]

That black area looks to be a cancerous growth.