Table 2.

TNM classifications of pheochromocytoma and paraganglioma

Primary Tumor (T)
Tx	Tumor cannot be assessed
T1	<5 cm in greatest diameter, no extra-adrenal invasion
T2	>5 cm or sympathetic paraganglioma of any size, no extra-adrenal invasion
T3	Any size with invasion into surrounding tissues (e.g., liver, pancreas, spleen, and and kidneys)
Nodal Involvement (N)
Nx	Regional lymph nodes cannot be Assessed
N0	No regional lymph node metastasis
N1	Regional lymph node metastasis
Distant metastases (M)
M0	No distant metastasis
M1	Distant metastasis
M1a	Metastasis to only bone
M1b	Metastasis to only distant lymph nodes/liver or lung
M1c	Metastasis to the bone and multiple
	other sites
Stage Groups
Stage 1	T1, N0, M0
Stage 2	T2, N0, M0
Stage 3	T1, N1, M0 or T2, N1, M0 or T3,
	Any N, M0
Stage 4	Any T, Any N, Any M1