​Differential diagnosis of tracheal obstruction

​Differential diagnosis of tracheal obstruction: 
-tracheal trauma 
-tracheal granuloma or papillomas 
-foreign body aspiration 
-extrinsic compression by tumor of thymus, thyroid, lung, aneurysm, congenital vascular rings, lymphadenopathy,
- primary tracheal tumor 
-metastatic tracheal tumour
-tracheal stenosis 
-congenital tracheal stenosis 
-acquired tracheal stenosis due to trauma or intubation