Tracheal diverticulum is a benign cystic mass in the cervical and mediastinal regions, with an incidence of 1% in post-mortem findings, and 2% in CT findings. The lesion is in most cases completely asymptomatic and is most commonly incidentally detected during a CT examination. We present the case of a young female patient with a tracheal diverticulum who has been followed up for 8 years by pediatric pneumologist. Patient health state deteriorated and she developed stress-induced dyspnea requiring surgical resection. Moreover, we mention differential diagnosis of other mediastinal cystic lesions.