TNM Classification

Following are the prognostic staging categories, histologic grades, and tumor/node/metastasis (TNM) classifications for cutaneous carcinoma of the head and neck according to the American Joint Committee on Cancer (AJCC).

Primary tumor (T)

• TX-Primary tumour cannot be evaluated; TIS-In situ carcinoma
• T1-Tumor with a maximum dimension of less than or equal to 2 cm
• T2-Tumor with a maximum dimension greater than 2 cm but less than or equal to 4 cm
• T3-Tumor with a maximum dimension of 4 cm or with perineural invasion or deep invasion or with mild bone erosion
• T4-Tumor with gross cortical bone/marrow invasion, invasion of the skull base, or invasion of the skull base foramen
• Gross cortical bone/marrow invasion in T4a tumour
• T4b-Tumor with invasion of the skull base and/or involvement of the skull base foramen

Regional lymph nodes (n)

Clinical N (cN):

• It is impossible to evaluate NX-Regional lymph nodes.
• N0-None of the local lymph nodes have spread.
• N1-Metastasis with no extranodal extension and a maximum diameter of 3 cm in a single ipsilateral lymph node (ENE [-])
• N2-Metastasis in one ipsilateral lymph node that is greater than 3 cm but less than 6 cm in greatest dimension and ENE (-); metastases in multiple ipsilateral lymph nodes, none greater than 6 cm in greatest dimension and ENE (-); or in bilateral or contralateral lymph nodes, none greater than 6 cm in greatest dimension and ENE (-)
• N2a-Metastasis in a single ipsilateral lymph node > 3 cm in maximum diameter but no more than 6 cm and ENE (-)
• Multiple ipsilateral lymph nodes with N2b-metastasis, none larger than 6 cm in maximum diameter, and ENE (-)
• N2c-Metastasis, none greater than 6 cm in maximum size, in bilateral or contralateral lymph nodes
• N3-Metastasis in any lymph node with clinically overt ENE (+) or metastasis in any lymph node with a maximum size of >6 cm.
• N3a-Metastasis in a lymph node with an ENE and a maximum diameter of 6 cm (-)
• Any node(s) with clinically overt ENE (+) and N3b-Metastasis

Pathological N (pN)

• It is impossible to evaluate NX-Regional lymph nodes.
• N0-None of the local lymph nodes have spread.
• N1-Metastasis in one ipsilateral lymph node with a maximum size of 3 cm and ENE (-)
• N2-Metastasis in a single ipsilateral lymph node with a greatest dimension and ENE of 3 cm or less (+); in a single ipsilateral lymph node with a greatest dimension and ENE of 3 cm to 6 cm (-); in metastases in multiple ipsilateral lymph nodes with a greatest dimension and ENE of no more than 6 cm (-); or in bilateral or contralateral lymph nodes with a greatest dimension and ENE of no more than 6 (-)
• N2a-Metastasis in a single ipsilateral lymph node with a greatest dimension and ENE (+) of 3 cm or less; or a greatest dimension and ENE (+) of 3 cm to 6 cm in a single ipsilateral lymph node (-)
• Multiple ipsilateral lymph nodes with N2b-metastasis, none larger than 6 cm in maximum diameter, and ENE (-)
• N2c-Metastasis, none greater than 6 cm in maximum size, in bilateral or contralateral lymph node(s) (-)
• N3-Metastasis in a lymph node with a greatest dimension greater than 6 cm and an ENE score of (-); in a single ipsilateral node with a greatest dimension greater than 3 cm and an ENE score of (+); in multiple ipsilateral, contralateral, or bilateral nodes, any of which have an ENE score of (+); or in a single contralateral node of any size and an ENE score of (+)
• N3a-Metastasis in a lymph node with an ENE and a maximum diameter of 6 cm (-)
• N3b-Metastasis in one ipsilateral node with a greatest dimension > 3 cm and ENE (+); in several ipsilateral, contralateral, or bilateral nodes, any of which have ENE (+); or in one contralateral node with a maximum dimension of any size and ENE (+)

Distant metastasis (M)

• No distant metastasis (cM0-)
• Distant metastasis cM1
• pM1-Confirmed distant metastases, as determined by microscopy