A previously healthy 15-year-old boy was admitted to the hospital because of recurrent episodic hemoptysis after physical exercise. A chest radiograph showed an opacity near the left hilum. The flow-volume curve showed high flows in the central airways and an abrupt fall at the level of the peripheral airways (Fig 1). A broncodilatation test was positive, without changing the curve shape. Exhaled nitric oxide, carbon monoxide diffusing capacity, skin prick tests to aeroallergens, tuberculin skin test, and QuantiFERON-TB Gold In-Tube results were normal. A contrast-enhanced chest CT scan showed symmetrical diffuse dilation of lobar and segmental bronchi, bilaterally (Fig 2, Video 1). A cylindrical vascular malformation (7×12 mm), interpreted as pulmonary venous ectasia, was detected at the apicoposterior segment of the superior left lobe, and, because no other abnormality was detected, it was hypothesized as being the site of origin of the bleeding (e-Fig 1). Bronchoscopy confirmed the dilatation of lobar and segmental bronchi (e-Fig 2). Only modest bleeding was observed during the procedure. BAL culture was positive for Staphylococcus aureus.