Bump on my cat's chin and gum area

I recently spotted a bump on Dexter's chin and gum area. I'm planning on taking him to the vet, but can somebody tell me what it could possibly be a result of? He isn't in pain or in distress, behaving perfectly normal and has his usual very healthy appetite.

Could it be a boil that needs draining? I know his teeth & gums are in need of a dental scrapping, which worries me if the bump is an abcessed tooth? (

Looks like a rodent ulcer, which isn't caused by rodents at all.

My guy has one of those as well but it is right at the base of his jaw where it meets the skull and I have no idea what it is but it is now much bigger than that. I have had it drained and tested two or three times and it is basically water. I know renal failure cats can get these but you should have the vet check it just to be sure.

It looks like some sort of cyst, I would recommend a vet visit.

Yes, this looks like it could be a rodent ulcer which is an auto-immune response type lesion. My Max gets these from time to time and my response is to bathe them in warm salt water which helps to reduce the inflammation. If you are using plastic, I would advise switching to ceramic and ensuring that drinking and eating bowls are washed regularly in case this is a reaction of some kind. 

In any event, a consultation with your vet is in order so you can know for sure what this is.

Thanks all for your advice. I'll be scheduling a vet visit after the Holidays.

I do use stainless steel dishes, however I believe I may have neglected washing them thoroughly. I'll try the warm water & salt remedy in the meantime.