Occult solitary fibrous tumour of the pleura presenting as recurrent spontaneous pneumothorax

A woman in her 30s, non-smoker, presented at the emergency department two times because of spontaneous pneumothorax. The first episode was treated with small bore catheter drainage, while during the second episode-occurring only 1 week later-thoracoscopic talcage was attempted. The postoperative course was characterised by slow clinical and radiological resolution, and recurrence 3 days after discharge. Eventually, multiportal video-assisted thoracoscopic exploration identified an interfissural solid mass. Resection and further work-up revealed the diagnosis of 'low-risk' solitary fibrous tumour (SFT) stage pT1N0M0. The interdisciplinary tumour board advised no adjuvant therapy. A CT thorax was scheduled in 1 year for follow-up. The patient was discharged without complications and has had no recurrences of pneumothorax at 6 months of follow-up. This report shows that SFT can easily be missed on initial presentation and should be considered in the differential diagnosis of pneumothorax, especially when frequently recurring.