Spontaneous pneumothorax secondary to radiographically occult lung metastasis from parapharyngeal synovial sarcoma: report of a case.

This report describes a case of secondary pneumothorax caused by a radiographically occult lung metastasis from parapharyngeal synovial sarcoma, a relatively rare tumor known to be highly metastatic to the lung. Although chest X-ray and thoracic computed tomography scan failed to detect the metastatic nodule in the right lung, the surgically resected specimen proved to be a 3-mm lung metastasis. To our knowledge, only eight cases of lung metastases from synovial sarcoma causing pneumothorax have ever been reported. In most of these cases, the lung metastases were detected by radiographical examinations. However, in this patient, the metastatic lesion was not detected during examination. It is speculated that secondary pneumothorax caused by synovial sarcoma may occur during the early stages of lung metastasis. Therefore, if pneumothorax occurs in a patient with a synovial sarcoma, the possibility of lung metastasis should be carefully considered, even if it is undetectable on radiological examinations.