* “Deep invasion” is defined as invasion beyond the subcutaneous adipose tissue or >6 mm (measured from the stratum granulosum of the adjacent epidermis to the base of the tumor). Perineural invasion as a criterion for T3 is defined as clinical or radiologic involvement of named nerves without involvement of the foramina or skull base.
Stage 0
Tis
N0
M0
Stage I
T1
Stage II
T2
Stage III
T3
T1, T2, T3
N1
Stage IV
N2, N3
T4
Any N
Any T
M1
>2 mm thickness
Clark level ≥ IV
Perineural invasion
Primary site ear
Primary site hair-bearing lip
Poorly differentiated or undifferentiated
Patients with primary cSCC or other cutaneous carcinomas with no evidence (clinical, radiologic, or pathologic) of regional or distant metastases are divided into two stages: Stage I for tumors measuring ≤ 2 cm in size and Stage II for those that are greater than 2 cm in size. In instances where there is clinical concern for extension of tumor into bone and radiologic evaluation has been performed (and is negative), these data may be included to support the Stage I vs. II designation. Tumors that are ≤ 2 cm in size can be upstaged to Stage II if they contain two or more high-risk features. Stage III patients are those with (1) clinical, histologic, or radiologic evidence of one solitary node measuring ≤ 3 cm in size or (2) Tumor extension into bone: maxilla, mandible, orbit, or temporal bone. Stage IV patients are those with (1) tumor with direct or perineural invasion of skull base or axial skeleton, (2) ≥ 2 lymph nodes or (3) single or multiple lymph nodes measuring >3 cm in size or (4) distant metastasis.