Huge thymoma: role of preoperative WHO histological classification.

A 57-year-old woman was admitted to our hospital with complaints of recent onset of dyspnea on exertion. A chest computed tomography revealed a large mediastinal mass which extrinsically compressed the heart and mediastinal structures, occupying one half of the hemithorax. A needle biopsy was performed to find a thymoma with type AB according to the WHO classification. Based on the radiological and histological finding a surgery for the tumor was achieved by exploratory VATS thoracotomy followed by thymectomy through a median sternotomy with tumor extirpation of 910 g in weight. A definite diagnosis of thymoma (Masaoka I) without capsular invasion was obtained from the pathologic findings, including positive immunohistochemical staining for CD1a and cytokeratin.