Thymic Masses of the Middle Mediastinum

Although thymic lesions are relatively common causes of anterior mediastinal masses, they can rarely arise in other mediastinal compartments, as it is well recognized that thymic tissue can lie in ectopic intrathoracic locations. A thymic mass within the middle mediastinum has rarely been reported, with only a single case of a thymic cyst described and no reports of a middle mediastinal thymoma. We report 2 thymic masses (1 thymoma and 1 thymic cyst) found to arise in the middle mediastinum.