Radiological features and diagnostic pitfalls of idiopathic azygos vein aneurysm: A case report

Introduction and importance: We present a case of idiopathic azygos vein aneurysm (AVA) and describe its radiological features. Clinicians should be aware of the imaging findings to avoid the risk of bleeding caused by biopsy.

Case presentation: An asymptomatic 46-year-old woman was found to have an abnormal shadow on a chest computed tomography (CT) scan during a medical checkup. Plain CT revealed a well-defined, homogeneous mass on the posterior side of the right main bronchus. Contrast-enhanced CT revealed a mass with marked enhancement pointing to a vascular structure. Three-dimensional reconstruction showed that the mass was connected to the azygos arch, and inflow to and outflow from the azygos vein was detected. Subsequently, video-assisted thoracic surgery was performed.

Clinical discussion: Patients with idiopathic AVA often present with accidental findings of a mediastinal or lung mass on a chest radiographs or CT scans, which can be mistakenly diagnosed as a paratracheal tumor, bronchial cyst, or posterior mediastinal tumor. Needle biopsy should be avoided due to the risk of massive bleeding. During the evaluation of thoracic malignancies, AVAs should be considered in the differential diagnosis, especially in area of the right tracheobronchial angle or right upper or posterior mediastinum. Three-dimensional reconstruction can help surgeons to clarify the disease diagnosis.

Conclusion: Imaging findings combined with enhanced CT and three-dimensional reconstruction are useful for diagnosing AVAs.