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': 'Not a posterior mediastinal tumor : \nSelect and explain. \nA. Neurofibroma, B. Lymphoma, C. Thymoma, D. Gastroenteric cyst', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans is 'c' ie Thymoma Mediastinum- is situated b/w the lungs in the center of the thorax.It is divided into 3 compartmentsAnterior or Anterosuperior it lies in front of the anterior pericardium & tracheaMiddle mediastinum or Visceral compartment it lies within the pericardial cavity including the tracheaPosterior mediastinum or paravertebral sulci it lies posterior to the post pericardium & tracheaLocations of the common Mediastinal MassesAnterior mediastinumMiddle MediastinumPost. MediastinumThymoma (most common in Ant med.)LymphomaGerm cell tumorsMesenchymal tumorsThyroid & parathyroid massesThymic cystCysts (MC in Mid. Med.)pleuropericardialbronchogenicenterogenousneuroentericVascular masses (aneurysm)Lymph node enlargement (including lymphoma)Mesenchymal tumorsPheochromocytomaMC tumor in middle Mediastinum- LymphomaNeurogenic tumors (MC overall)MeningoceleGastroenteric cystMesenchymal tumorsPheochromocytomaLymphoma", 'role': 'assistant'}]