This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thorax And Mediastinum, Subject name: Surgery
Not a posterior mediastinal tumor: 
Select and explain. 
A. Neurofibroma, B. Lymphoma, C. Thymoma, D. Gastroenteric cyst
C: Thymoma
Answer: C: Thymoma 
Explanation: Posterior Mediastinum Neurogenic tumors (MC overall) Meningoceles Mesenchymal tumours Pheochromocytoma Lymphoma Bochdalek hernia Bronchogenic cyst Enterogenous cyst EXTRA EDGE: MC anterior MM: ThymomaQ MC middle MM: Cyst(Pericardial cyst is MC) MC posterior MM: Neurogenic tumors MC MM (overall): Neurogenic tumors MM seen in all three compaments of mediastinum: Lymphoma, bronchogenic cyst & mesenchymal tumors IOC for diagnosis of MM (except neurogenic tumors): CT