Table 3 Definition of regional lymph node (N)
Extent of regional lymph node and/or lymphatic metastasis | ||
|---|---|---|
N Category | Number of tumor-involved regional lymph node | Presence of in-transit, satellite, and/or microsatellite metastases |
NX | Regional nodes not assessed (e.g., SLN biopsy not performed, regional nodes previously removed for another reason) Exception: pathological N category is not required for T1 melanomas, use cN, if regional lymph nodes not assessed for patient with T1 melanoma | No |
N0 | No regional metastases detected | No |
N1 | One tumor-involved node or any number of in-transit, satellite, and/or microsatellite metastases with no tumor-involved nodes | |
N1a | One clinically occult (i.e., detected by SLN biopsy) | No |
N1b | One clinically detected | No |
N1c | No regional lymph node disease | Yes |
N2 | Two or three tumor-involved nodes or any number of in-transit, satellite, and/or microsatellite metastases with one tumor-involved node | |
N2a | Two or three clinically occult (i.e., detected by SLN biopsy) | No |
N2b | Two or three, at least one of which was clinically detected | No |
N2c | One clinically occult or clinically detected | Yes |
N3 | Four or more tumor-involved nodes or any number of in-transit, satellite, and/or microsatellite metastases with two or more tumor-involved nodes, or any number of matted nodes without or with in-transit, satellite, and/or microsatellite metastases | |
N3a | Four or more clinically occult (i.e., detected by SLN biopsy) | No |
N3b | Four or more, at least one of which was clinically detected, or presence of any number of matted nodes | No |
N3c | Two or more clinically occult or clinically detected and/or presence of any number of matted nodes | Yes |
