Spontaneous pneumothorax associated with cavitating pulmonary metastasis from breast cancer: a case report and literature review.

We report a 69-year-old woman with spontaneous pneumothorax associated with cavitating pulmonary metastasis from breast cancer. She was treated for right breast cancer (invasive ductal carcinoma, ypT4bN1M0, stage IIIB) 2 years earlier, and was admitted for right pneumothorax and chest computed tomography, which showed multiple small cavitating lesions in bilateral lungs. The pneumothorax was treated conservatively with chest drainage, but subsequently recurred ipsilaterally. During video-assisted thoracic surgery, we detected small white nodules with visceral pleural rupture; therefore, we performed partial lung resection. The pathological findings revealed metastatic breast cancer with pleural invasion. Forty days later, ipsilateral pneumothorax recurred, and chemical pleurodesis was performed, which resolved the pneumothorax and prevented subsequent recurrence. Early diagnosis and definitive treatment, including pleurodesis, should be considered to prevent recurrence of spontaneous pneumothorax and improve patients' quality of life, even in patients with advanced malignancy.