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Head & Neck Staging: Table One
| TNM Classification | Histological/Clinical Features |
|---|---|
| T1 | 2 cm or less |
| T2 | > 2 but < 4 cm |
| T3 | > 4 cm |
| T4(lip) | Invades through cortical bone, inferior nerve, floor of mouth, or skin of face, i.e, chin or nose |
| T4a | (Oral cavity) invades adjacent structures (e.g., through cortical bone, into deep [extrinsic] muscle of tongue [genioglossus, hypoglossus, palataglossus, and styloglossus], maxillary sinus, skin of face) |
| T4b | Tumor invades masticator space, pterygoid plates, or skull base and/or encases internal carotid artery |
Note: Superficial erosion alone of bone/tooth socket by gingival primary is not sufficient to classify as T4.