SESSION TYPE: Miscellaneous Case Report Posters I
PRESENTED ON: Tuesday, October 23, 2012 at 01:30 PM - 02:30 PM
INTRODUCTION: Vascular malformations may appear as mass on imaging.
CASE PRESENTATION: 62 year old female underwent CT chest that revealed subpleural nodules. Eighteen months after initial CT scan, a 2.0 x 1.7cm mass was identified in the middle mediastinum at the level of the aortopulmonary window, deviating the esophagus to the left. There was no associated lymphadenopathy. The patient denied pulmonary or gastrointestinal symptoms. Her physical exam was notable only for retrognathia, Mallampati III and no palpable lymphadenopathy. Differential diagnosis of pathologic mediastinal lymph node versus an esophageal lesion such as leiomyoma was proposed and biopsy was suggested. Repeat CT of the chest performed with thin cuts and intravenous contrast demonstrated the middle mediastinal mass had contiguity with the azygos vein and filled slowly with contrast. No intervention was performed and the patient remains asymptomatic.
DISCUSSION: Aneurysm of the azygos vein is a rare, incidental finding in surgery or on imaging in an asymptomatic patient. The etiology is often idiopathic and presumed to be congenital. The segment of the azygos that joins the superior vena cava is of different embryologic origin from the rest of the azygos vein. This segment is susceptible to weakness in the media of the vein. (1) If patients are symptomatic they report chest tightness, dysphagia, palpitations or cough. Acquired aneurysms are typically secondary to liver or vascular disease. The diagnosis on imaging can be complicated. Case reports indicate azygos vein aneurysms have been resected after being misdiagnosed as a solid mass. (3) As a venous structure contrast fills the azygos slowly and may appear as an enhancing mass in the pathway of the azygos vein. Clues to diagnosis include change in size of mass from a supine and upright position as it is vascular, slow filling of contrast secondary to venous phase, location in the right posterior mediastinum, the connecting structure arching over the right bronchus and the “mass” draining at the superior vena cava of the fourth thoracic vertebrae. (1) There is no clear consensus regarding treatment. Watchful waiting, surgical excision and stent-graft placement have been proposed. Advocates of more aggressive intervention reference case reports of azygos vein aneurysm associated with massive pulmonary embolus. (2)
CONCLUSIONS: The diagnosis of azygos vein aneurysm remains a rare finding and challenging diagnosis. Watchful waiting appears to be the most appropriate management strategy although catastrophic clinical sequelae have been rarely reported in the literature.
1) Gallego M, et al. Idiopathic azygos vein aneurysm: a rare cause of mediastinal mass. Thorax 1999; 54: 653-655
2) Nakamura Y, et al. Surgical excision of a thrombosed azygos vein aneurysm causing pulmonary embolism. J Thorac Cardiovasc Surg 2007; 133: 834-5
3) Santamaria N, et al. Azygos vein aneurysm forming a mediastinal mass. Arch Bronconeumol. 2006; 42 (8): 410-2
DISCLOSURE: The following authors have nothing to disclose: Kelly Newton, Dina KiaNoury
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