• Corticosteroid-induced mediastinal widening with simulated focal lymphadenopathy was found in a patient having myasthenia gravis. To my knowledge, this is the first report of such changes occurring in a patient having myasthenia gravis. As the use of corticosteroids in the treatment of myasthenia gravis becomes more common, this association can be expected to occur more often. Reemphasis of this phenomenon should help to avoid unnecessary surgical intervention in these patients.