Lump behind my Cats front leg

[Daston]

Hey guys,

My cat was sat on my lap the other night and I noticed a small lump behind his front leg near his chest (sort of armpit area). Its hard and seems to move around when I squeezed it he dosn't seem to be in any pain and is eating fine.

He is an indoor cat although does scrap a bit with his brother (mostly play fighting). He has just turned 4 and other than a bad case of fleas the other month he has been his normal bouncy chatty self.

Have got him booked into the vets later this week just to play it safe, but just wondered what you guys thought it could be.