Bronchogenic cyst causing unilateral ventilation-perfusion mismatch

A 24-year-old woman presented with dysphagia and shortness of breath. Ventilation-perfusion lung imaging demonstrated global reduction in perfusion with normal ventilation in the entire right lung. CT and MRI showed a large subcarinal maas compatible with a bronchogenic or esophageal duplication cyst. Histologic examination after surgical excision revealed findings typical for a bronchogenic cyst. Previous case reports of bronchogenic cysts detected with scintigraphy have documented complete absence of perfusion and matched ventilation-perfusion defects within the right lung. This case report demonstrates a bronchogenic cyst that caused reduced perfusion with normal ventilation within the right lung (unilateral ventilation-perfusion mismatch). Although pulmonary embolism may cause a unilateral ventilation- perfusion mismatch, other conditions that cause extrinsic compression of central pulmonary vasculature also need to be considered in patients with this scintigraphic finding.