<prompt> Most common anterior mediastinal tumour isThymomaNeurogenic tumorLymphomaTeratoma  <response>: Thymoma: 2181- H 18th editionMEDIASTINAL MASSESAnterior mediastinumThymoma Most commonLymphomaTeratomatous neoplasmsThyroid massesMiddle mediastinum- Vascular masses Most common- Lymph node enlargement from metastasis or granulomatous disease- Pleuropericardial and bronchogenic cystsPosterior mediastinum- Neurogenic tumours Most common- Meningoceles, meningomyelocele- Gastroenteric cysts- Esophageal diverticula Investigation of choice - CT-scan Definite diagnosis - Mediastinoscopy or anterior mediastinotomy 