Table 2.
American Joint Committee on Cancer classification for staging of cutaneous squamous cell carcinoma of the head and neck, 8th edition.
| T | Primary tumor | ||
|---|---|---|---|
| TX | Primary tumor cannot be assessed | ||
| Tis | Carcinoma in situ | ||
| T1 | Tumor smaller than or equal to 2 cm in greatest dimension | ||
| T2 | Tumor >2 cm but smaller than or equal to 4 cm in greatest dimension | ||
| T3 | Tumor >4 cm in maximum dimension or minor bone erosion or perineural invasion or deep invasion* | ||
| T4 | Tumor with gross cortical bone/marrow, skull base invasion, and/or skull base foramen invasion | ||
| T4a | Tumor with gross cortical bone/marrow invasion | ||
| T4b | Tumor with skull base invasion and/or skull base foramen involvement | ||
| Clinical N (cN) | |||
| cN | Regional lymph nodes | ||
| NX | Regional lymph nodes cannot be assessed | ||
| N0 | No regional lymph node metastasis | ||
| N1 | Metastasis in a single ipsilateral lymph node ⩽3 cm in greatest dimension and no ENE (−) | ||
| N2 | Metastasis in a single ipsilateral lymph node >3 cm but not more than 6 cm in greatest dimension and ENE (−); or metastases in multiple ipsilateral lymph nodes, none >6 cm in greatest dimension and ENE (−); or in bilateral or contralateral lymph nodes, none >6 cm in greatest dimension and ENE (−) | ||
| N2a | Metastasis in a single ipsilateral lymph node >3 cm but not more than 6 cm in greatest dimension and ENE (−) | ||
| N2b | Metastasis in multiple ipsilateral lymph nodes, none >6 cm in greatest dimension and ENE (−) | ||
| N2c | Metastasis in bilateral or contralateral lymph nodes, none >6 cm in greatest dimension and ENE (−) | ||
| N3 | Metastasis in a lymph node >6 cm in greatest dimension and ENE (−); or metastasis in any node(s) with clinically overt ENE (+) | ||
| N3a | Metastasis in a lymph node >6 cm in greatest dimension and ENE (−) | ||
| N3b | Metastasis in any node(s) with clinically overt ENE (+) | ||
| NX | Regional lymph nodes cannot be assessed | ||
| N0 | No regional lymph node metastasis | ||
| Pathological N (pN) | |||
| pN | Regional lymph nodes | ||
| N1 | Metastasis in a single ipsilateral lymph node ⩽3 cm in greatest dimension and ENE (−) | ||
| N2 | Metastasis in a single ipsilateral lymph node, 3 cm or smaller in greatest dimension and ENE (+) or a single ipsilateral lymph node >3 cm but not more than 6 cm in greatest dimension and ENE (−); or metastases in multiple ipsilateral lymph nodes, none >6 cm in greatest dimension and ENE (−); or in bilateral or contralateral lymph nodes, none >6 cm in greatest dimension and ENE (−) | ||
| N2a | Metastasis in a single ipsilateral lymph node, 3 cm or smaller in greatest dimension and ENE (+) or a single ipsilateral lymph node >3 cm but not more than 6 cm in greatest dimension and ENE (−) | ||
| N2b | Metastasis in multiple ipsilateral lymph nodes, none >6 cm in greatest dimension and ENE (−) | ||
| N2c | Metastasis in bilateral or contralateral lymph node(s), none >6 cm in greatest dimension and ENE (−) | ||
| N3 | Metastasis in a lymph node >6 cm in greatest dimension and ENE (−); or in a single ipsilateral node >3 cm in greatest dimension and ENE (+); or multiple ipsilateral, contralateral, or bilateral nodes, any with ENE (+); or a single contralateral node of any size and ENE (+) | ||
| N3a | Metastasis in a lymph node >6 cm in greatest dimension and ENE (−) | ||
| N3b | Metastasis in a single ipsilateral node >3 cm in greatest dimension and ENE (+); or multiple ipsilateral, contralateral, or bilateral nodes, any with ENE (+); or a single contralateral node of any size and ENE (+) | ||
| M | Distant metastasis | G | Histologic grade |
| M0 | No distant metastasis | GX | Grade cannot be assessed |
| M1 | Distant metastasis | G1 | Well differentiated |
| G2 | Moderately differentiated | ||
| G3 | Poorly differentiated | ||
| G4 | Undifferentiated | ||
Abbreviations: ENE, extranodal extension; G, grade; T, tumor; N, node; M, metastasis.