Abstract
A 75-year-old woman was referred to our hospital for evaluation of abnormal shadows on a routine chest roentgenogram. Chest CT scans showed two separate anterior mediastinal masses the size and findings of which were the same.
After obtaining a diagnosis of thymoma with CT-guided needle biopsy, we resected both tumors combined with sorrounding thymic tissues via a median sternotomy. Those tumors were found, one in the right and the other in the left lobe of the thymus. Both tumors were encapsulated solid masses 4 cm in diameter.
Microscopically, the tumors were consistent with thymoma of the predominant lymphocytic type. Immunohistochemical study, using Leu7 and cytokeratin, showed similar characteristics between the tumors. However, because the tumors had the same size and non-invasive nature, we considered that their origin was multicentric development rather than intra-thymic metastasis.
