Azygos Vein Aneurysm Mimicking a Calcified Lymph Node

A 66-year-old female who had been receiving treatment for a non-tuberculous pulmonary mycobacterial infection underwent enhanced computed tomography (CT). A wellcircumscribed, high density nodule, measuring 12 mm in diameter, was noted in the right main bronchus (Picture 1) and it was initially considered to be a calcified mediastinal lymph node that had been caused by the mycobacterial infection. However a plain CT scan conducted 2 months later produced no abnormal findings (Picture 2). Subsequent CT angiography showed the presence of contrast material in a fusiform azygos vein aneurysm (AVA) from 12 seconds (Picture 3) after the infusion of the contrast material, suggesting that the blood stream, flowing backward from the superior vena cava, had thus become stagnated in the AVA.