Signs in chest radiology- The hilum overlay sign

By Dr Deepu

The hilar overlay sign is another sign described by Felson.The hilum overlay sign refers to an appearance on frontal chest X ray of patients with a mass at the level of the hilum which is in fact either anterior or posterior to the hilum.

When a mass arises from the hilum, the pulmonary vessels will be in contact with the mass and hence their silhouette is obliterated. The ability to see and trace the edges of the vessels through the mass implies that the mass is not contacting the hilum, and is therefore either anterior or posterior to it. 

Most of these masses usually are found to be in the anterior mediastinum.

want to read more in chest radiology??? Have a look at the following pages

Chest Radiology

Signs in Chest Radiology