Spontaneous pyopneumothorax in patients treated with mTOR inhibitors for subpleural pulmonary metastases.

Spontaneous pyopneumothorax is a very rare occurrence, even in cancer treated patients. Here we present two consecutive cases of spontaneous pyopneumothorax that occurred early after initiation of mTOR inhibitors for the treatment of renal cell carcinoma with subpleural pulmonary metastasis. In these two cases, necrosis and excavation of lung metastasis were observed, suggesting their involvement in the pathogenic mechanism of pyopneumothorax. This report extends the available experience of the pulmonary side effects of these novel targeted therapies.