Do any of the hand or arm bones have non 100% scale on them? Looks to me like the hand bones are inheriting scale from a parent somewhere in the hierarchy above them. Also, which version of 3ds Max is this?
It does look like it's Skin rather than CAT that's being wonky. I've not rigged anything in max for a couple of years but I too have seen skin create silly sized envelope bone thingies on several occasions. iirc you can edit them manually and copy/mirror them in the same way you can vertex weights