What is Rotti Largo's terminal illness?

TVTropes.org, which looks at various conventions throughout movies, call it an "Incurable Cough of Death", one of the signs in any movie that a character will not make it to the end. They expand on this though, saying:

Rotti's terminal disease, which is heavily implied to be an untreatable cancer by the doctor's statement, "You don't have a lot of time. It's spreading rapidly."

Ultimately though, his illness is never explicitly stated.

It could be anything fatal. The world was going through an epic organ failure crisis, he was just another victim who got lucky for far too long.

It's symbolic meaning is that no matter how much money you got if you don't take care of yourself you're in trouble. It also represents his bitterness which ultimately manifested inside himself and called his own downfall.