[Thymic Cancer Associated with Spontaneous Regression of Multilocular Thymic Cysts]

Thymic cancer associated with spontaneous regression of thymic cysts is a rare disease. A 47-yearold man was referred to our hospital for right chest pain and chest abnormal shadow. Chest computed tomography( CT) revealed a solid lesion 1.3 cm in diameter and a cystic lesion 1.0 cm in diameter at the right anterior mediastinum. A second CT study after six months showed a solid lesion increased to 1.7 cm in diameter and a cystic lesion reduced to 0.7 cm in diameter. A second magnetic resonance imaging (MRI) showed a cystic lesion reduced and high signal intensity region in the thymus enlarged on T2-weighted imaging. Under the diagnosis of thymoma associated with multilocular thymic cysts, total thymectomy was performed for these mediastinal lesions by video-assisted thoracic surgery. Histopathological finding was thymic squamous cell carcinoma (Masaoka stage II) associated with multilocular thymic cysts. Additional postoperative radiotherapy was performed, and there has been no recurrence after one postoperative year.