Summary of AJCC (8th Edition) TNM staging for CSCC* (adapted from Cañueto and Román-Curto176)
| Stage | Primary tumor (T) | Lymph node (N) | Metastasis (M) |
| 0 | In situ primary tumor | No lymph node metastasis (clinical or pathological exam) | No distant metastasis |
| I | Tumor ≤2 cm across | No lymph node metastasis (clinical or pathological exam) | No distant metastasis |
| II | Tumor >2 cm but ≤4 cm across | No lymph node metastasis (clinical or pathological exam) | No distant metastasis |
| III | Tumor ≤2 cm across | Metastasis in an isolated ipsilateral lymph node ≤3 cm, no ENE† (clinical or pathological exam) | No distant metastasis |
| Tumor >2 cm but ≤4 cm across | Metastasis in an isolated ipsilateral lymph node ≤3 cm, no ENE† (clinical or pathological exam) | No distant metastasis | |
| Tumor >4 cm across, minor bone invasion, perineural invasion, or deep invasion‡ | No lymph node metastasis (clinical or pathological exam) | No distant metastasis | |
| Tumor >4 cm across, minor bone invasion, perineural invasion, or deep invasion‡ | Metastasis in an isolated ipsilateral lymph node ≤3 cm, no ENE† (clinical or pathological exam) | No distant metastasis | |
| IV | Tumor ≤2 cm across | Clinical exam: Metastasis in an isolated ipsilateral lymph node >3 to ≤6 cm, no ENE† Metastasis in multiple ipsilateral lymph nodes ≤6 cm, no ENE† Metastasis in bilateral or contralateral lymph nodes ≤6 cm, no ENE† | No distant metastasis |
| Pathological exam: Metastasis in an isolated ipsilateral lymph node ≤3 cm, ENE-positive† Metastasis in an isolated ipsilateral lymph node >3 cm to ≤6 cm; No ENE† Metastasis in multiple ipsilateral lymph nodes ≤6 cm, no ENE† Metastasis in bilateral or contralateral lymph nodes ≤6 cm, no ENE† | |||
| Tumor >2 cm but ≤4 cm across | Clinical exam: Metastasis in an isolated ipsilateral lymph node >3 to ≤6 cm, no ENE† Metastasis in multiple ipsilateral lymph nodes ≤6 cm; No ENE† Metastasis in bilateral or contralateral lymph nodes ≤6 cm; No ENE† | No distant metastasis | |
| Pathological exam: Metastasis in an isolated ipsilateral lymph node ≤3 cm; ENE-positive† Metastasis in an isolated ipsilateral lymph node >3 cm to ≤6 cm, no ENE† Metastasis in multiple ipsilateral lymph nodes ≤6 cm, no ENE† Metastasis in bilateral or contralateral lymph nodes ≤6 cm, no ENE† | |||
| Tumor >4 cm across, minor bone invasion, perineural invasion, or deep invasion‡ | Clinical exam: Metastasis in an isolated ipsilateral lymph node >3 to ≤6 cm, no ENE† Metastasis in multiple ipsilateral lymph nodes ≤6 cm, no ENE† Metastasis in bilateral or contralateral lymph nodes ≤6 cm, no ENE† | No distant metastasis | |
| Pathological exam: Metastasis in an isolated ipsilateral lymph node ≤3 cm, ENE-positive† Metastasis in an isolated ipsilateral lymph node >3 cm to ≤6 cm, no ENE† Metastasis in multiple ipsilateral lymph nodes ≤6 cm, no ENE† Metastasis in bilateral or contralateral lymph nodes ≤6 cm, no ENE† | |||
| Tumor with gross cortical bone and/or marrow invasion, skull base invasion and/or skull base foramen invasion | Nearby lymph node(s) may or may not be positive (clinical or pathological) | No distant metastasis | |
| Any tumor size or depth | Clinical exam: Metastasis in a lymph node >6 cm, no ENE† Metastasis in any lymph node(s) and ENE-positive† (clinically overt) | No distant metastasis | |
| Pathological exam: Metastasis in a lymph node >6 cm, no ENE† Metastasis in an isolated ipsilateral lymph node >3 cm, ENE-positive† Metastasis in multiple ipsilateral, contralateral or bilateral lymph nodes; any with ENE-positive† Metastasis in a single contralateral lymph nodes (any size), ENE-positive† | |||
| Any tumor size or depth | Nearby lymph node may or may not be positive (clinical or pathological) | Distant metastasis |
*The AJCC 8th Edition staging table was developed for CSCC of the head and neck.
†ENE is defined as extension through the lymph node capsule in the surrounding connective tissue with or without stromal reaction.
‡Deep invasion is defined as invasion beyond the subcutaenous fat or >6 mm (measured from the granular layer of adjacent normal epidermis to the base of the tumor); perineural invasion is defined as tumor cells in the nerve sheath of a nerve lying deeper than the dermis or measuring ≥0.1 mm in caliber or presenting with clinical or radiographic involvement of named nerves without skull base invasion or transgression.
AJCC, American Joint Committee on Cancer; CSCC, cutaneous squamous cell carcinoma; ENE, extranodal or extracapsular nodal extension; M, metastasis; N, lymph node; T, primary tumor; TNM, tumor, node, metastasis.