Massive Thymic Hyperplasia in Graves Disease

Thymic hyperplasia (TH) is a rare but established complication of Graves disease (GD). It is a benign phenomenon that regresses with appropriate treatment of GD. We report the case of a Burmese refugee with newly diagnosed GD, who had an incidental thymic mass measuring 70 mm × 21 mm × 121 mm. The size of the mass exceeded typical reports in the literature but was not accompanied by a substantial thyrotoxicosis. As the mass receded with antithyroid medication, a presumptive diagnosis of TH was ultimately made. Recognition of this association is vital to prevent unnecessary biopsy and surgical intervention.