Table 1. AJCC 7th edition N staging system and the modified N staging system.

Stage	AJCC 7th edition N staging system	Modified N staging system
N0	No regional lymph node metastasis	No regional lymph node metastasis
Nx	Regional lymph nodes cannot be assessed	Regional lymph nodes cannot be assessed
N1	Metastasis in a single inguinal lymph node	Metastasis in one to two unilateral inguinal lymph nodes without ENE
N2	Metastasis in multiple or bilateral inguinal lymph nodes	Metastasis in three unilateral or metastasis in two to three bilateral inguinal lymph nodes without ENE
N2	Metastasis in multiple or bilateral inguinal lymph nodes	Unilateral or bilateral metastasis in four or more inguinal lymph nodes without ENE, ENE of LNM or pelvic lymph node(s)
N3	Unilateral or bilateral ENE of LNM or pelvic lymph node(s)	Unilateral or bilateral metastasis in four or more inguinal lymph nodes without ENE, ENE of LNM or pelvic lymph node(s)

Abbreviations: ENE=extranodal extension; LNM=lymph node metastasis.