<prompt> Not a posterior mediastinal tumor :NeurofibromaLymphomaThymomaGastroenteric cyst  <response>: Ans is c ie Thymoma Mediastinum- is situated bw 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 aneurysmLymph node enlargement including lymphomaMesenchymal tumorsPheochromocytomaMC tumor in middle Mediastinum- LymphomaNeurogenic tumors MC overallMeningoceleGastroenteric cystMesenchymal tumorsPheochromocytomaLymphoma 