Mediastinum
General
Staging-thymic tumors
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Last author update: 1 September 2018
Last staff update: 10 May 2021
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PubMed Search: Thymoma staging[TI]
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Cite this page: Bychkov A. Staging-thymic tumors. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/mediastinumthymomastaging.html. Accessed April 26th, 2024.
Definition / general
- Thymoma, thymic carcinoma, thymic neuroendocrine tumors and combined thymic carcinoma are covered by this staging system
- First introduced in AJCC 8th edition (Amin: AJCC Cancer Staging Manual, 8th Edition, 2017)
- AJCC/TNM staging is used for predicting outcomes of thymic tumors, such as recurrence (in the lower stages) and disease specific survival (in the higher stages); reference numbers are available (J Thorac Oncol 2014;9:S65)
- Pre operative clinical staging is based on physical examination and imaging; post operative clinical staging may be supplemented by pathological findings
- Stage is determined primarily by levels of local invasion of a thymic malignancy into surrounding mediastinal structures (T classification) while nodal involvement and metastatic spread are much rarer events
- There is no recommended histologic grading system for thymic tumors
- Other staging systems also exist (Lung Cancer 2014;83:126)
Essential features
- AJCC 7th edition staging was sunset on December 31, 2017; as of January 1, 2018, use of the 8th edition is mandatory
- T, N and M categories are the mainstay for predicting recurrence and survival in patients with thymic tumors
- Local invasion (T category) is the primary determinant of staging
Primary tumor (T)
- TX: primary tumor cannot be assessed
- T0: no evidence of primary tumor
- T1: tumor encapsulated or extending into the mediastinal fat, may involve the mediastinal pleura
- T1a: tumor with no mediastinal pleura involvement
- T1b: tumor with direct invasion of mediastinal pleura
- T2: tumor with direct invasion of the pericardium (either partial or full thickness)
- T3: tumor with direct invasion into any of the following: lung, brachiocephalic vein, superior vena cava, phrenic nerve, chest wall or extrapericardial pulmonary artery or veins
- T4: tumor with invasion into any of the following: aorta (ascending, arch or descending), arch vessels, intrapericardial pulmonary artery, myocardium, trachea, esophagus
Notes:
- Involvement must be microscopically confirmed in pathological staging, if possible
- T categories are defined by levels of invasion; they reflect the highest degree of invasion regardless of how many other (lower level) structures are invaded
- T1, level 1 structures: thymus, anterior mediastinal fat, mediastinal pleura
- T2, level 2 structures: pericardium
- T3, level 3 structures: lung, brachiocephalic vein, superior vena cava, phrenic nerve, chest wall, hilar pulmonary vessels
- T4, level 4 structures: aorta (ascending, arch or descending), arch vessels, intrapericardial pulmonary artery, myocardium, trachea, esophagus
Regional lymph node (N)
- NX: regional lymph nodes cannot be assessed
- N0: no regional lymph nodes metastasis
- N1: metastasis in anterior (perithymic) lymph nodes
- N2: metastasis in deep intrathoracic or cervical lymph nodes
Note:
- Involvement must be microscopically confirmed in pathological staging, if possible
AJCC prognostic stage grouping
| Stage I: |
T1a, T1b |
N0 |
M0 |
|
| Stage II: |
T2 |
N0 |
M0 |
|
| Stage IIIA: |
T3 |
N0 |
M0 |
|
| Stage IIIB: |
T4 |
N0 |
M0 |
|
| Stage IVA: |
any T |
N1 |
M0 |
|
|
any T |
N0, N1 |
M1a |
|
| Stage IVB: |
any T |
N2 |
M0, M1a |
|
|
any T |
any N |
M1b |
|
Board review style question #1
A 62 year old man presented with a large thymic carcinoma directly invading pericardium and no
metastatic spread. What is the pT category per the AJCC/TNM 8th edition?
- pT1a
- pT1b
- pT2
- pT3
- pT4
Board review style answer #1
Board review style question #2
What is the major predictor of thymic carcinoma recurrence?
- Distant metastasis
- Extent of local invasion
- Histological type
- Nodal metastasis
- Size of tumor
Board review style answer #2
B. Extent of local invasion. T category (local invasion) is a major predictor of recurrence while N and M categories significantly influence survival.
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Reference:
Staging-thymic tumors
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