Hilum Overlay Sign on Chest X-Ray
If a mass is in contact with the pulmonary vessels then, according to the silhouette sign, we would expect the outlines of the vessels to be lost. However, if the edges of the vessels are appreciated then it implies that the mass is not in contact with the vessels and is thus either anterior or posterior to the hilum:
In this case, the hilar vessels are seen through the mass. This was later proven to be an anterior mediastinal teratoma.

Dr. Devpriyo Pal @drdevrad

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