From: Skin Cancer Treatment (PDQ®)
PDQ Cancer Information Summaries [Internet].
Bethesda (MD): National Cancer Institute (US); 2002-.
NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.
Table 1. Definitions of Primary Tumor (T) for Cutaneous Carcinoma of the Head and Necka
| T Category | T Criteria |
|---|---|
| TX | Primary tumor cannot be identified. |
| Tis | Carcinoma in situ. |
| T1 | Tumor ≤2 cm in greatest dimension. |
| T2 | Tumor >2 cm, but ≤4 cm in greatest dimension. |
| T3 | Tumor >4 cm in maximum dimension or minor bone erosion or perineural invasion or deep invasion.b |
| 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. |
aReprinted with permission from AJCC: Cutaneous carcinoma of the head and neck. In: Amin MB, Edge SB, Greene FL, et al., eds.: AJCC Cancer Staging Manual. 8th ed. New York, NY: Springer, 2017, pp. 171–81.
bDeep invasion is defined as invasion beyond the subcutaneous fat or >6 mm (as measured from the granular layer of adjacent normal epidermis to the base of the tumor); 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 in caliber, or presenting with clinical or radiographic involvement of named nerves without skull base invasion or transgression.