TNM Classification : Malignant melanoma of skin

T- Primary tumor

TX - Primary tumor cannot be assessed

TO - No evicence of primary tumor

Tis - Melanoma in situ (Clark level I), (atypical melanocytic hyperplasia, severe melanocytic dysplasia, not an invasive malignant lesion)

T1 - Tumor 0.75 mm or less in thickness and invades the papillary dermis (Clark level II) 

T2    - Tumor more than 0.75 mm but not more than 1.5 mm in thiskness and.or invades to the papillary-reticular dermis interface (Clark level III) 

T3 - Tumor more than 1.5 mm but not more than 4.0 mm in the thiskness, and/or invades the reticular dermis (Clark level IV)

T3a - Tumor more than 1.5 mm but not more than 3.0 mm in thiskness 

T3b - Tumor more than 3.0 mm but not more than 4.0 mm in thiskness 

T4 - Tumor more than 4.0 mm in thiskness, and/or invades subcutanesous tissue (Clark level V) and/or satellite(s) within 2 cm of the primary tumor

T4a - Tumor more than 4.0 mm in thickness and/or invades subcutanesous tissue T4b - Satellite(s) within 2 cm of the primary tumor

Notes: in case of discrepancy between tumor thickness and level, the T category is based on the less favorable finding.

N - Regional lymph nodes

NX - Regional lymph nodes cannot be assessed NO - No regional lymph node metastasis

N1 - Metastasis 3 cm or less in greatest dimension in any regional lymph node(s) N2 - Metastasis more than 3 cm in greatest dimension in any regional lymph node(s) and/or in-transit metastasis

N2a - Metastasis more than 3 cm in greatest dimension in any regional lymph node(s)

N2b - In-transit metastasis

N2c - Both

M - Distant metastasis

MX - Distant metastasis cannot be assessed MO - No distant metastasis M1 - Distant metastasis

M1a - Metastasis in skin or subcutaneous tissue or lymph node(s) beyond the regional lymph nodes

M1b - Visceral metastasis