Thymus staging

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This article deals with thymus staging. An introduction to staging is in the cancer staging systems article.

Thymic staging, thymus cancer staging, thymic carcinoma staging, Masaoka-Koga classification, and thymus tumour staging redirect here.


There is a system by Masaoka and colleagues[1] that was subsequently modified, and is known as the modified Masaoka staging system.[2]

Based on CAP protocol

Staging as per Butnor et al.:[3]

Stage Characteristics
I encapsulated lesion, tumour does not penetrate capsule
IIa microscopic penetration of the capsule
IIb macroscopic penetration of the capsule
III macroscopic invasion of adjacent organs
IVa pleural or pericardial spread
IVb lymphatic or hematogenous spread ‡


  • ‡ The International Thymic Malignancy Interest Group (ITMIG) notes that is must have spread to distant organs.[4] This implies that lymphovascular invasion within the tumour itself is not sufficient for calling stage IVb.

Modified Masaoka as per Masaoka et al. (1999)

T-stage - based on Masaoka et al. (1999):[5]

Stage Features
T1 macroscopically and microscopically encapulated
T2 macroscopic invasion or adhesion to surrounding tissue (fat or pleura) or microscopic invasion into the capsule
T3 Spread to adjacent organs, e.g. pericardium, lung, great vessels.
T4 pericardial or pleural spread

N-stage - based on Masaoka et al. (1999):[5]

Stage Features
N0 no lymph node spread
N1 spread to anterior mediastinal lymph nodes
N2 spread to intrathoracic lymph nodes other than the mediastinal lymph nodes
N3 spread to supraclavicular lymph nodes

M-stage - based on Masaoka et al. (1999):[5]

Stage Features
M0 no hematogeneous spread and extrathoracic lymph nodes with the exception of the supraclavicular nodes
M1 hematogeneous spread and/or extrathoracic lymph nodes

See also


  1. Masaoka, A.; Monden, Y.; Nakahara, K.; Tanioka, T. (Dec 1981). "Follow-up study of thymomas with special reference to their clinical stages.". Cancer 48 (11): 2485-92. PMID 7296496.
  2. Koga, K.; Matsuno, Y.; Noguchi, M.; Mukai, K.; Asamura, H.; Goya, T.; Shimosato, Y. (May 1994). "A review of 79 thymomas: modification of staging system and reappraisal of conventional division into invasive and non-invasive thymoma.". Pathol Int 44 (5): 359-67. PMID 8044305.
  3. Butnor KJ et al. Thymus. Version 2011. URL: Accessed on: 31 August 2015.
  4. URL: Accessed on: May 13, 2016.
  5. 5.0 5.1 5.2 Masaoka, A.; Yamakawa, Y.; Fujii, Y. (Mar 1999). "Well-differentiated thymic carcinoma: is it thymic carcinoma or not?". J Thorac Cardiovasc Surg 117 (3): 628-30. PMID 10047676.

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