What is the most likely diagnosis? 
              
- 53 year-old man with neck pain following fall

                  
              Axial CT Images of Trachea
            
              - Thyroid Cyst
- Zenker's Diverticulum
- Pneumomediastinum
- Paratracheal Air Cyst
- Mounier-Kuhn Syndrome
Additional Image - Sagittal Reconstruction of Trachea
             
              
             
            
               
              Additional Images
               
              
              Sagittal Reconstruction of Trachea
              
             
            
              
                  Answer:
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                4. Paratracheal Air Cyst
              
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              More (Click Discussion Tab) 
             
            
              
              
              Paratracheal Air Cysts
              General Considerations
              
                - Benign incidental       finding on CT (rarely seen on chest radiographs)
- 2.0% to 3.7% of the       population
- Most are probably       tracheal diverticulum
                    
                      - On imaging, 35%  have a narrow stalk to the trachea
 
                  - Histology shows  ciliated columnar epithelium
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