Which chest X-ray finding may raise suspicion for mediastinal widening suggestive of a dissection?

• A. Widening of the mediastinum
• B. Left lower lobe infiltrate
• C. Pleural effusion
• D. Normal mediastinum

Answer: (A)

Mediastinal widening on a chest X-ray is a red flag for acute aortic pathology, such as dissection. The mediastinum houses the aorta, and a dissection can create hematoma or an expanding aortic contour that makes the overall silhouette appear wider. When a patient has sudden chest or back pain, or hypertension with concerning symptoms, this radiographic finding should prompt urgent further imaging, typically CT angiography, to confirm dissection and guide management.

Other findings described—like a left lower lobe infiltrate or a pleural effusion—point to infection/aspiration or fluid buildup, not specifically to dissection. A normal mediastinum would not raise suspicion for dissection based on the radiograph alone, since the dissection can still be present even if the mediastinal contour appears normal on X-ray. However, the radiograph’s sensitivity is limited, so a high clinical index of suspicion leads to definitive imaging with CT angiography.