Role of advanced magnetic resonance imaging in the assessment of malignancies of the mediastinum

Table 4 The tumor node metastasis staging system by International Thymic Malignancy Interest Group

		TNM staging
Tumor (T) descriptor		I	II	IIIA	IIIB	IVA	IVB
T1a	Encapsulated or unencapsulated tumor, with or without extension into fat	X				X	X
T1b	Invasion of mediastinal pleura	X				X	X
T2	Invasion of pericardium		X			X	X
T3	Involvement of lung, chest wall, phrenic nerve, brachiocephalic vein, superior vena cava, or hilar (extrapericardial) pulmonary vessels			X		X	X
T4	Invasion of thoracic aorta, arch vessels, main pulmonary artery, trachea, esophagus, or myocardium				X	X	X
Node (N) descriptor		I	II	IIIA	IIIB	IVA	IVB
N0	No lymph node metastasis	X	X	X	X	X	X
N1	Involvement of anterior (perithymic) lymph nodes					X	X
N2	Involvement of deep intrathoracic or cervical lymph nodes						X
Metastasis (M) descriptor		I	II	IIIA	IIIB	IVA	IVB
M0	No Metastasis	X	X	X	X	X (N1)	X (N2)
M1a	Pleural or pericardial metastatic nodule or lesions					X (N0,1)	X (N2)
M1b	Pulmonary intraparenchymal metastastic nodule or distant organ metastasis						X (any T, N)

TNM: Tumor node metastasis staging system; ITMIG: International Thymic Malignancy Interest Group.