This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Which of the following is TRUE about branchial cyst? 
Select and explain. 
A. Usually seen along the posterior border of the sternocleidomastoid muscle, B. Mostly arises from 2nd branchial system, C. Always present in preschool children, D. Conservatory treatment is indicated
B: Mostly arises from 2nd branchial system
Answer: B: Mostly arises from 2nd branchial system 
Explanation: Branchial cleft cysts usually present as a soft cystic mass along the anterior border of the sternocleidomastoid muscle. These lesions are usually recognized in the second or third decades of life. To prevent recurrent infection and possible carcinoma, they should be completely excised, along with their fistulous tracts. First branchial cleft cysts present high in the neck, sometimes just below the ear. A fistulous connection with the floor of the external auditory canal may be present. Second branchial cleft cysts, which are far more common, may communicate with the tonsillar fossa. Third branchial cleft cysts, which may communicate with the piriform sinus, are rare and present low in the neck. Ref: Lustig L.R., Schindler J.S. (2013). Chapter 8. Ear, Nose, & Throat Disorders. In M.A. Papadakis, S.J. McPhee, M.W. Rabow, T.G. Berger (Eds), CURRENT Medical Diagnosis & Treatment 2014.