[Indication of video-assisted thoracic surgery for mediastinal mass lesions]

Most of mediastinal tumors are benign cysts and neoplasms. Resection is indicated for cystic lesions because of possibility of malignancy, compression symptom and possible rupture in future. However careful observation might be appropriate for asymptomatic tumors without risk of malignancy. Although video-assisted thoracoscopic surgery (VATS) is increasingly performed, its indication is still controversial.

Among 37 mediastinal cystic lesions with confirmed pathological diagnosis, 17 were neoplasms. All of 20 non-neoplastic lesions have cyst wall thinner than 5 mm. Five cases( 29%) of neoplastic lesions have cyst wall thinner than 5 mm. Three of them underwent preoperative fluorodeoxyglucose-positron emission tomography( FDG-PET) or PET-computed tomography( CT). All 3 neoplastic lesions with thin wall showed accumulation of FDG. None of non-neoplastic cyst had FDG accumulation. Ninety-seven patients underwent surgical resection for mediastinal tumors. Out of 51 VATS, 2 were converted to open thoracotomy. One patient with thymoma had ipsilateral pleural recurrence after VATS. Tumor sizes of those 3 patients were larger than 7 cm.

Cystic mediastinal tumor with wall thickness less than 5 mm and no FDG accumulation might be observed without resection because it is very unlikely to be a neoplasm. Mediastinal tumor larger than 7 cm might not be suitable for VATS.