Thyroid Storm and Incidental Anterior Mediastinal Teratoma: Coincidence or Correlation?

Teratoma is a rare cause of thyrotoxicosis. Among the different types of teratoma, struma ovarii is the main type which contains thyroid tissue. There is no evidence in the literature that would indicate mediasternal teratoma would also lead to thyrotoxicosis or thyroid storm. Herein we report a 37-year-old woman who suffered from palpitation. Her chest X-ray showed a mass lesion at the left hilum, and chest computed tomography scan yielded a suspicion of pericardial cyst. Thereafter, video-assisted thoracoscopic surgery was performed, and thymic cyst was diagnosed during the operation. However, subsequent pathological studies confirmed a diagnosis of mature cystic teratoma. A thyroid function test demonstrating hyperthyroidism was completed prior to the patient's operation, and thyroid storm was diagnosed by clinical presentation. The patient's symptoms did not improve after the operation until we added beta blocker and anti-thyroid agents. Therefore, was the presence of thyroid storm and anterior mediastinal teratoma coincident or correlative in this case? The special stain of teratoma tissues did not reveal any thyroid tissues. In conclusion, thyroid storm and anterior mediastinal teratoma in our case occurred coincidentally. However, a survey of possible hyperthyroidism in patients with anterior mediastinal tumor before operation is critical to avoid perioperative complications.