Masaoka staging system of thymoma

Last revised by Dr Yuranga Weerakkody on 15 May 2022

The Masaoka staging system is commonly adopted for thymomas 1-3, and is the most important determinant of survival following surgical resection 4:

  • stage I: intact thymic capsule
  • stage II: capsular invasion into adjacent mediastinal fat or pleura
  • stage III: macroscopic invasion into adjacent organs, vessels
  • stage IV
    • IVa: dissemination in thoracic cavity (i.e. pleural or pericardial implants) 
    • IVb: distant metastases

Stage II and above are regarded as thymic carcinoma 2.

ADVERTISEMENT: Supporters see fewer/no ads

Cases and figures

  • Case 1
    Drag here to reorder.
  • Case 2: stage I
    Drag here to reorder.
  • Updating… Please wait.

     Unable to process the form. Check for errors and try again.

     Thank you for updating your details.