INTRODUCTION
An uncommon, but potentially serious, cause of respiratory disorders in childhood is represented by the extrinsic tracheal compression due to congenital vascular anomalies within the mediastinum [1]. The most severe forms are usually diagnosed during the neonatal period, while the less severe forms can be detected later in life, when unexplained chronic or recurrent respiratory symptoms, or occasional mild dysphagia, lead to endoscopic evaluations. In two retrospective studies we found that the most prevalent respiratory symptoms associated with this condition were chronic cough, poorly responsive to therapy, and recurrent lower respiratory tract infections (LRTI) [2,3]. In the absence of known comorbidities, these symptoms are often misdiagnosed as asthma, non-specific bronchial hyperreactivity and/or gastroesophageal reflux and inappropriate prescription of anti-asthmatic drugs and/or antibiotics often occurs [3,4]. The generation of cough in these children is thought to be induced by mechanical sensory inputs, through rapidly adapting mechanoreceptors [3,5]. The recurrence of LRTI in these otherwise healthy children is believed to be related to the dynamic collapse of the airway lumen, associated with malacia, that reduces cough effectiveness and interferes with mucociliary clearance [6-8]. Under-recognition and under-treatment of subclinical protracted bacterial infections may lead to the development of chronic suppurative lung disease and bronchiectasis [8]. With this background a retrospective study was performed to evaluate whether tracheal malacia, secondary to abnormal mediastinal vessels, is associated with persistent lower respiratory tract inflammation and infection.