hilum overlay sign

hilum overlay sign

Imaging A radiologic finding consisting of a well-circumscribed mass in the anterior or posterior mediastinum which may simulate an enlarged cardiac border and be misinterpreted as cardiomegaly Etiology Tumors, abscesses, TB
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A chest X-ray (CXR) was performed, and the antero-posterior view demonstrated the hilum overlay sign. Furthermore, there was absence of the azygo-oesophageal line and bilateral paraspinal lines.
Felson described the hilum overlay sign as the visualisation, on a frontal X-ray, of the first bifurcation of either the left or right pulmonary artery more than 1 cm medial to the lateral edge of the cardiac shadow.
The hilum overlay sign is present on a frontal chest radiograph when normal hilar structures can be visualised through a mass, which implies that the mass is either anterior or posterior to the hilum.