This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Medicine
The most common posterior mediastinal mass is 
Select and explain. 
A. Neurogenic tumor, B. Lymph nodes, C. Neurogenic parasitic cyst, D. Teratoma
A: Neurogenic tumor
Answer: A: Neurogenic tumor 
Explanation: The posterior mediastinum contains the following structures: sympathetic ganglia, nerve roots, lymph nodes, parasympathetic chain, thoracic duct, descending thoracic aoa, small vessels and the veebrae. Most masses in the posterior mediastinum are neurogenicnature Ref Davidson 23rd edition pg 580