Azygos lobe

68-year-old man presented with exertional dyspnea. On examination, mild pretibial edema was present on both sides. A chest radiograph showed cardiomegaly with right pleural effusion; notably, an uncommon structure close to the upper mediastinum was detected in the right lung (Fig. 1). An azygos lobe was indicated by the coronal image of chest computed tomography without contrast medium (Fig. 2, arrow). The three-dimensional reconstruction confirmed that the azygos lobe (Fig. 3, arrowheads) was separated from the right upper lobe of the lung by an azygos fissure (arrows) extending to an abnormally located azygos vein (asterisk).