Anomalous systemic arterial supply to normal basilar segments of the lower lobe of the left lung.

A 38-year-old man with an anomalous systemic arterial supply from the descending thoracic aorta to the normal basilar segments of the left lower lobe experienced symptoms of progressive exertional dyspnea. Although the pulmonary parenchyma was normal, there was no pulmonary arterial supply to the basilar segments of the left lower lobe. Left lower lobectomy was performed because of worsening left-to-left shunt. Aortography and pulmonary arteriography form the cornerstone for diagnosis, but a less invasive diagnostic method with less patient suffering is high-resolution computed tomography, which might replace bronchography for accurate evaluation of the distribution and patency of the bronchial tree and delineation of the characteristic "Medusa's hair"-like anomalous vascular supply penetrating into the nearly normal pulmonary parenchyma.