There are no general screening procedures for apparently healthy people. About a third of all thymoma cases are discovered during a routine or diagnostic chest x-ray. Myasthenia gravis, characterized by ever-worsening muscle weakness, is associated with a thymoma in up to 50 percent of cases. Removing the tumor will produce a complete remission of the myasthenia gravis in about one-third of patients, and at least half will improve.
