My son has a soft lump about the size of a silver dollar below his knee on the inside of the shin. We have a new cat that he plays with alot. Like all cats that are played with has scratched him on the hands, very small scartches but the tops of his hands look like he has a rash on them that is starting to dry up. He is 8 years old and the only reason we found the lump was that he said his knee had bothered him a little yeasterday. As I was checking it out I found the lump that he says doesn't really hunt when touched but I did not put any pressure on it.