Note 1: If there is a discrepancy between the Clark level and the pathologic description of extent, use the higher (more extensive) code.
Note 2: Satellite or in-transit metastasis are coded under CS Lymph Nodes.
Note 3: If there is no documentation of ulceration in the pathology report, assume ulceration is not present.
Note 4: Ulceration is determined by histopathological examination and not on clinical evaluation.
|00||In situ: Noninvasive; intraepidermal
Clark's level I
Basement membrane of the epidermis is intact
|10||Papillary dermis invaded
Clark's level II
|20||Papillary-reticular dermal interface invaded
Clark's level III
|30||Reticular dermis invaded
Clark's level IV
|50||Subcutaneous tissue invaded (through entire dermis)
Clark's level V
|80||Further contiguous extension:
Underlying cartilage, bone, skeletal muscle
|95||No evidence of primary tumor||T0||U||U|
* For Extension codes 10 - 80, and 99 ONLY, the T category is assigned based on value the of Site-Specific Factor 1, Measured Thickness and Site-Specific Factor 2, Ulceration, as well as Extra Table 1, Thickness and Ulceration and Extra Table 2, Extension and Ulceration.