Stage IV includes: (T1, N2, M0); (T2, N2, M0); (T3, N2, M0); (Any T, N3, M0); (T4, Any N, M0); (Any T, Any N, M1). T1: Tumor smaller than 2 cm in greatest dimension. T2: Tumor 2 cm or larger, but smaller than 4 cm in greatest dimension. T3: Tumor 4 cm or larger in greatest dimension or minor bone erosion or perineural invasion or deep invasion. Deep invasion is defined as invasion beyond the subcutaneous fat or larger than 6 mm; perineural invasion for T3 classification is defined as tumor cells within the nerve sheath of a nerve lying deeper than the dermis or measuring 0.1 mm or larger in caliber, or presenting with clinical or radiographic involvement of named nerves without skull base invasion or transgression. T4: Tumor with gross cortical bone/marrow, skull base invasion and/or skull base foramen invasion. N2: Metastasis in a single ipsilateral lymph node, 3 cm or smaller in greatest dimension and ENE(+); or metastasis in a single ipsilateral lymph node larger than 3 cm but not larger than 6 cm in greatest dimension and ENE(-); or metastases in multiple ipsilateral lymph nodes, none larger than 6 cm in greatest dimension and ENE(-); or metastases in bilateral or contralateral lymph nodes, none larger than 6 cm in greatest dimension and ENE(-). N3: Metastasis in a lymph node larger than 6 cm in greatest dimension and ENE(-); or metastasis in a single ipsilateral lymph node larger than 3 cm in greatest dimension and ENE(+); or metastases in multiple ipsilateral, contralateral, or bilateral lymph nodes, any with ENE(+). M0: No distant metastasis. M1: Distant metastasis. (AJCC 8th ed.) [from NCI]