Sounds like the description of what Abby has on her belly...our vet said most likely a hy---(I can't remember what it is called...but started with "hy") which is a relatively common occurrence in some breeds such as boxers. Nothing dangerous and typically it comes off on it's own in 2 to 3 months. If not, then they will cut it off. They did however test for cancer cells which came back negative. Good luck!