A mediastinal mass: Graves' disease related thymic hyperplasia.

A 35-year-old woman presented with symptoms of pulmonary embolism and thyrotoxicosis. Computed tomography of the chest ruled out pulmonary embolism but showed an incidental mediastinal mass. Graves' disease was confirmed and the mediastinal mass was ascribed to associating thymic hyperplasia. Treatment of Graves' thyrotoxicosis resulted in a spontaneous shrinkage of the mediastinal mass. Although it is relatively unknown, thymic hyperplasia is a normal and reversible manifestation of Graves' disease.