Unusual cause of recurrent pneumothorax: excavated metastasis of osteosarcoma.

We report the case of a recurrent right pneumothorax, revealing metastasis of an osteosarcoma, 40 months after complete remission. Seven years after surgical excision, the patient is still considered in complete remission. Pneumothorax is rarely the first manifestation of lung metastasis. Osteosarcoma is the most frequent primary tumor. Chest computed tomography detects excavated or subpleural lung metastasis. Differential diagnosis between benign and malignant bullous lesions is important because surgical excision affects survival in some malignancies.