The azygos lobe and vein: interesting and typical clinical image.

1 of 2 DESCRIPTION A 38-year-old male admitted to the hospital with chest pain for few days. He does not have any signifi cant medical and surgical problems. Physical examination, lab work, imaging studies and exercise cardiolite stress were normal. Eventually, we concluded that this chest pain was most likely secondary to musculoskeletal origin. We found azygos lob incidentally on chest x-ray and computed axial tomography of chest. These images have typical appearance of azygos lobe, fi ssure and vein. The azygos lobe (azygos lobe in fi gures 1 and 2 ) is a uncommon anomaly that is found in 1% of anatomic specimens, 1 on about 0.4% of chest radiographs 2 and 1.2% of high resolution CT. 3 The azygos lobe is a developmental anomaly but not a true accessory lobe. On chest radiographs, azygos fi ssure (azygos fi ssure in fi gure 1 ) is visible as a fi ne convex line and its upper portion has triangular shape due to extrapleural areolar tissue and lower portion has tear-shaped shadow due to azygos vein (azygos vein in fi gure 1 ). Anatomy of azygos lobe is clinically important during thoracic surgical procedures. Cases of spontaneous pneumothorax have reported in patients with azygos lobe.