Imaging features and outcomes in 10 cases of idiopathic azygos vein aneurysm

Background Idiopathic azygos vein aneurysm (AVA) is rare. This retrospective study evaluated the imaging features and outcomes in 10 cases of idiopathic AVA. Methods We retrospectively evaluated 10 patients with surgically proven or typical imaging features of idiopathic AVA encountered in our institution between 1990 and 2012. Chest roentgenography and computed tomography (CT) were performed in all 10 patients, and magnetic resonance imaging (MRI) was performed in 4 of these patients. The clinical features, AVA morphologic characteristics, and outcomes were analyzed. Results Chest roentgenograms showed a right paratracheal nodule or mediastinal mass in 7 cases. CT and MRI disclosed 4 thrombosed saccular AVAs (short axis, 3-6 cm; mean, 4.7 cm) and 6 fusiform AVAs (short axis, 2.2-3 cm; mean 2.7 cm). Two large saccular AVAs that presented with chest tightness were resected shortly after diagnosis. One saccular AVA manifested as a pulmonary embolism, whereas the remaining AVA was asymptomatic; they showed 25% to 40% short-axis growth in a 3- to 5-year interval before subsequent AVA resection. Conversely, all 6 fusiform AVAs were asymptomatic and found incidentally, remaining rather stable with less than 8% short-axis growth during 3 to 8 years of follow-up. Compared with fusiform AVAs, saccular AVAs were larger and had a greater frequency of AVA-related symptoms, intralesional thromboses, and greater than 20% short-axis growth during the follow-up period. Conclusions Saccular AVAs are larger than fusiform aneurysms, presenting with greater frequency of chest symptoms, intralesional thrombosis, considerable lesion growth, and need for surgical intervention. In contrast, fusiform AVAs are asymptomatic and rather stable in long-term follow-up.