All Sample Questions

Branchial Cleft Cyst 1

Question

Question: A 5-year-old boy is brought to the pediatrician by his mother because of difficulty swallowing. Physical examination reveals a persistent cervical sinus on the lateral aspect of the neck. The pediatrician explains that this is a congenital defect. Which of the following embryological structures failed to obliterate during development and led to this defect?

Choices

A. First pharyngeal arch

B. Second pharyngeal arch

C. Third pharyngeal arch

D. Fourth pharyngeal arch

E. Second pharyngeal cleft

Answer

E. Second pharyngeal cleft

Explanation

The patient's difficulty swallowing and persistent cervical sinus on the lateral aspect of the neck indicates a branchial cleft cyst, which is a congenital defect resulting from failure of the second pharyngeal cleft to obliterate during embryological development. Normally, the second through fourth pharyngeal clefts form temporary cervical sinuses, which are obliterated by proliferation of the second pharyngeal arch. Failure of this obliteration process results in a persistent cervical sinus, which can present as a lateral neck mass (branchial cleft cyst). This cyst may become infected, leading to difficulty swallowing. The pharyngeal arches contribute to different structures in the head and neck and are not involved in this process. The first arch forms the maxilla, zygoma, mandible among other structures. The second arch forms the stapes, styloid process, lesser horn of hyoid, stylohyoid ligament. The third arch forms the greater horn of the hyoid and part of the hyoid bone. The fourth arch forms the laryngeal cartilages.