My Bombay cat is roughly 10 years old and for about a year or two, he’s had a soft lump on his stomach area with a black spot on the top. I had it checked out and the vet didn’t seem very concerned but never gave me a definitive answer. It stays about the same size however about 6 months ago, it was suddenly gone. There was just a black dot on his skin and everything looked pretty normal but in less than a week the lump came back as quickly as it left and returned the same size as before. It doesn’t seem to bother him or affect his behavior in any way, It’s just something that I would like to learn more about