Cats have lumps on lower abdomen near ?

Both of my cats have this big lump way down there abdomen right above their . I was thinking cancer but both of them have it so I'm just wondering. They are neutered but that was back in May. Is that lump in all male cats or just mine? Its like squishy and you can grab all of it with your hand. Maybe its fat? Any ideas would be appreciated, thanks in advance ;]. Oh they are a year old by the way and appear to be in good health.