McRaney, star of TV's "Major Dad" and "Simon & Simon," is expected to remain at the hospital for a few days before returning to his Los Angeles home, Entertainment Tonight reported Tuesday.
The tumor was found when McRaney, 57, went to the doctor for an exam before having minor knee surgery.
The actor reportedly is a longtime smoker.
McRaney, married to actress Delta Burke, is to star as a Beverly Hills, Calif., tycoon in the upcoming WB series "Commando Nanny."
Scarlett Johansson steps out with fiance after pregnancy reveal
Teacher apologizes for showing sexual image of herself in class