We present two cases of spontaneous pneumothorax secondary to metastatic synovial cell sarcoma. Radiographic techniques initially did not suggest lung nodules in either patients; thoracoscopy allowed sequential bilateral detection of small pulmonary metastases in one case and confirmed the diagnosis during treatment of recurrent pneumothorax in the second case. This report underlines that pneumothorax may be the first clinical manifestation of metastatic sarcoma and can occur even if current imaging techniques are not indicative of metastatic disease. In the latter instance, thoracoscopic exploration has to be envisaged in order to rule out the possibility of metastatic lung involvement.