system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A lesion with sharp outlines extending above the clavicles suggests?
assistant
The correct answer is  Ans BThe anterior mediastinum ends below the clavicle while the apical lobes of upper lung lobes extend superior to the clavicles more posteriorly hence if a mass lies in the posterior mediastinum its margins would be lined by air filled lungs and hence seen as sharp margins. This is an extension of the Silhouette sign - the Cervico-thoracic sign.