Scabbard Trachea; True is?: (A) Flattening of trachea, (B) Caused by lateral compression by swellings, (C) Caused by lateral compression by tumors, (D) All of the above
Answer is D. SCABBARD (SABER-SHEATH) TRACHEA

Flattening of trachea caused by lateral compression by swellings or tumors.
Causes: Carcinoma thyroid, thyroiditis, carcinoma larynx, goitre.