Thymic Hyperplasia and Graves Disease: Management of Anterior Mediastinal Masses in Patients with Graves Disease

ObjectiveTo describe a case of an anterior mediastinal mass (AMM) in a patient with Graves disease.MethodsWe report the clinical presentation, diagnosis, management, and outcome of a 34-year-old man with dyspnea on exertion.ResultsInitial evaluation of the patient’s complaints revealed a large AMM on chest radiography and then chest computed tomography. After occurrence of additional symptoms, the patient was diagnosed as having Graves disease and treated with antithyroid medications. Despite an appropriate biochemical response, he continued to experience severe dyspnea on exertion. A repeated computed tomographic scan 8 weeks after initiation of therapy showed no appreciable decrease in size of the AMM. He elected to undergo thymectomy. An intraoperative phrenic nerve injury resulted in a paralyzed left hemidiaphragm, leaving the patient with considerable difficulties in his career and profoundly decreased exercise tolerance.ConclusionThe differential diagnosis of an AMM includes several malignant lesions with a risk often warranting early surgical excision. In light of the association of benign thymic hyperplasia with Graves disease, thymectomy may be delayed in expectation of thymic regression with medical therapy. The timing of regression is variable, and very few reports exist in the literature. In our current case, the patient opted for thymectomy relatively early and had an unfortunate complication. The lack of clinical evidence regarding management of an enlarged thymus in patients with Graves disease, however, makes management decisions more difficult. (Endocr Pract. 2009;15: 534-539)