Correct!
Answer: 3. The “dense hilum” sign
Figure 1 shows the” dense hilum” sign. The “dense hilum” sign is present when one hilum appears clearly denser than the contralateral hilum on a frontal chest radiograph, and implies the presence of a lesion within or projected over the abnormal hilum. Compare the density of the left hilum in Figure 1A, obtained at the time of presentation, with that of Figure 1B, which is a chest radiograph obtained 2 years earlier. Normally the left hilum is somewhat cephalic to the right, and both hila are roughly of equal density. In Figure 1, the left hilum is noticeably denser than the right. Importantly, this observation represents a change compared to the chest radiograph obtained 2 years earlier- compare the left hilum in Figure 1A and Figure 1B.
The “silhouette sign” represents the lack of visualization of a border on a chest radiograph that is normally rendered visible because the juxtaposing structures creating the border are of different density. Recall that the visibility of a border on a chest radiograph requires the juxtaposition of structures of different density. When the silhouette sign is present, the juxtaposing structures are of similar density, and the border between two structures of equal density cannot be visualized. “Golden’s S” sign occurs when a central mass produces right upper lobe atelectasis, resulting in superior displacement of the right minor fissure, creating an “S” shape. The medial portion of the “S” faces laterally and inferiorly, and is created by the mass causing hilar enlargement and right upper lobe bronchial obstruction, with cephalic displacement of the lateral portion of the right minor fissure, forming the lateral portion of the “S”. The “cervicothoracic” sign refers to the notion that a mass on chest radiography that has a lateral border visible superior to the clavicle must be located within the posterior mediastinum, and not the anterior mediastinum, owing to the anteriorly downward sloping orientation of the cervicothoracic junction. In other words, an anterior mediastinal lesion near the thoracic inlet will no longer contact lung and create a visible border because such a lesion will enter the neck at this point and lose contact with lung, whereas a posterior mediastinal lesion may still contact the lung at a level cephalic to the clavicle, creating a visible border on chest radiography. Finally, the “scimitar sign” refers to a curvilinear density, representing partial anomalous pulmonary venous return, typically found along the right heart border coursing inferiorly and medially, so named for its resemblance to a Turkish sword of the same name.)
Follow up thoracic CT (Figure 2) was performed.
Figure 2. Click here for a movie of the axial CT.
Characterize the thoracic CT findings. Which of the following is correct?
