Solitary fibrous tumour of the pleura arising in a pulmonary cavity.

Solitary fibrous tumour of the pleura (SFTP) arising in a cavity is extremely rare. A 66-year-old Japanese male presented with an abnormal shadow on his chest X-ray. Chest computed tomography showed a cavity of approximately 18 mm in diameter between the upper and lower lobes that contained a solid nodule within. Under the thoracoscope, the peduncle cystic tumour was removed with sufficient surgical margin. Macroscopically, a tumour of about 15 mm in diameter arose in the cystic cavity. Immunohistochemical stains were positive for CD34, bcl-2, and signal transduction and activator of transcription 6 (STAT6) but negative for smooth muscle actin (SMA), desmin, and epithelial membrane antigen (EMA), and a diagnosis of SFTP was made. The patient remains well without recurrence or any complications at two and a half years after the operation. SFTP should be considered when a tumour arises in a cavity existing in an interlobar space. It is important to determine whether the tumour is pedunculated or sessile during surgery and to perform the appropriate surgical procedure.