A 56 year-old woman (treated for ovarian cystadenocarcinoma 9-yrs before) presented a slowly increasing dyspnea. CT-scan revealed a mediastinal cyst with typical radiological pattern compatible with benign pleuro-pericardial cyst. The cyst was removed via right thoracoscopy. Surprisingly, the pathology were indicative of cystic mediastinal recurrence from ovarian adenocarcinoma.