Seriously what causes that? I competed in one show with a guy that had a stomach like that exactly. He was pregnant with a 6 pac. I couldn't stop staring. And of course Genova needs help.
Just a guess, but IMO, the gut is permanently distended, because Lenny used to be real big and real fat, with the stomach hanging down, out of the bottom of his shirt.
You can see him in an old powerlifting video he's in on Youtube. So with the gut being "pulled out" all those years and hanging, it turns into a permanent distorted abdomen.
(Again, just a guess). Either that or his organs are gigantic from heavy HGH use...