A 79-year-old woman was given a diagnosis of scalp angiosarcoma. Treatment with interleukin-2 and radiotherapy aclieved a complete response. However, a few months later, the patient presented with multiple thin-walled cavitary metastases in the right lung and pneumothorax. The pneumothorax was successfully treated but soon relapsed. The patient died of respiratory failure at home. Lung metastasis of malignant tumors should be considered one cause of relapsing pneumothorax.