This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Mediastinum, Cysts, and Neoplasms, Subject name: Surgery
[{'content': 'Anterior mediastinal mass in 18 yrs old male - \nSelect and explain. \nA. Thymoma, B. Ectopic gland, C. Aneunysm, D. Lymphoma', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Thymoma Mediastinumo It is situated b/w the lungs in the center o the thoraxo It is divided into 3 compartmentsy Anterior or Anterosuperioro It lies in front of the anterior pericardium &trachea.y Middle mediastinum or Visceral compartmento It lives within the pericardial cavity including the tracheay Posterior mediastinum or paravertebral suleio It lies posterior to te post pericardium & trachea Anatomic division of the mediastinumLocations of the common Mediastinal MassesAnterior mediastinumMiddle MediastinumPost. Mediastinumo Thymoma (most common in Ant. med.)o Cysts (MC in Mid. Med.)o Neurogenic tumors (MC overall)# pleuropericardialo Meningoceleso Lymphoma# bronchogenico Gastroenteric cysto Germ cell tumors# enterogenouso Mesenchymal tumorso Mesenchymal tumors# neuroenterico Pheochromocytomao Thyroid & parathyroid masseso Vascular masses (aneurysm)o Lymphomao Lymph node enlargement (including lymphoma)o Thymic cysto Mesenchymal tumorso Pheochromocytomao MC tumor in middle Mediastinum-Lymphoma", 'role': 'assistant'}]