This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Neck, Subject name: Surgery
[{'content': 'A 25 years old male patient presents to the outpatient department with a midline swelling in the neck. O/E there is no movement of the swelling on swallowing, but the swelling moves on protrusion of the tongue. The likely origin of the swelling is \nSelect and explain. \nA. 1st & 2nd branchial arch, B. 4th branchial pouch, C. 4th branchial arch, D. Midline endoderm of pharynx', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Answer: d) Midline endoderm of pharynxTHYROGLOSSAL CYSTArise from the midline endoderm of pharynxMost common site is the sub-hyoid regionMidline swelling (except in the region of thyroid cartilage where it is pushed usually to the left side)Congenital but swelling presents at the age of 15-30 yrsThyroglossal fistula is always acquiredCyst can be moved sideways but not up and downMoves up with the protrusion of tongue; moves with deglutitionRarely papillary carcinoma may developSurgery - Sistrunk operation (removal of the cyst + track + central part of hyoid bone + portion of the tongue base up to the foramen cecum', 'role': 'assistant'}]