Thymic hyperplasia commonly presents in association with Grave's disease. We report on a patient in whom Grave's disease was diagnosed after thymectomy. The patient, a 53-year-old man, was initially suspected to have thymoma, thymectomy was performed. Tachycardia and a high-grade fever developed immediately after surgery, suggesting thyroid crisis. The patient was treated with antithyroid drugs and beta blockers. The patient's condition improved thereafter, and the patient was discharged on the 18th hospital day. Histopathological examination of the resected thymic tissue revealed thymic hyperplasia. To our knowledge, there have been no reported cases of Grave's disease which had not been detected until the development of postoperative thyroid crisis, as in our patient. Therefore, we report this case with discuss the treatment performed.
