TNM classification of primary cutaneous carcinomas

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Clinical practice guidelines for keratinocyte cancer > TNM classification of primary cutaneous carcinomas


Appendix A provides updated information on staging using UICC TNM 8,[1] which should be used for all tumours diagnosed after 1 January 2018.

This combines the UICC TNM 8 guidance for skin carcinoma of the head and neck and carcinoma of the skin (essentially limbs and trunk but excluding eyelid, vulva, penis, non-hair bearing lip and non-hair bearing perianal skin within 5cm of the perianal margin).

This includes basal cell carcinoma, squamous cell carcinoma and adnexal carcinomas, but excludes Merkel cell carcinoma.

Primary tumour (pT)

UICC TNM 8 states pT is identical to T.

pTX Primary tumour cannot be assessed
pT0 No evidence of primary tumour
pTis Carcinoma in situ
pT1 Tumour ≤20mm or less in maximum dimension (this is the clinical dimension but the pathological dimension, usually macroscopic, can be used if the clinical is not available)
pT2 Tumour >20mm to ≤40mm in maximum dimension (this is the clinical dimension but the pathological dimension, usually macroscopic, can be used if the clinical is not available)
pT3 Tumour >40mm in maximum dimension (this is the clinical dimension but the pathological dimension, usually macroscopic, can be used if the clinical is not available)

pT1 or pT2 can be upstaged to pT3 by one or more high-risk clinical/pathological features including deep invasion*, specifically defined perineural invasion** or minor bone erosion

pT4a Tumour with gross cortical/marrow invasion
pT4b Tumour with axial skeleton/skull base/foraminal invasion

High-risk features in relation to pT1 and pT2 upstaging to pT3:
*Deep invasion: this is defined as depth of invasion (DOI) to a level beyond the subcutaneous fat and/or tumour depth/thickness >6mm. Depth is measured in millimetres from the granular layer of the nearest adjacent normal epidermis to the deepest point of the tumour.
**Specifically defined perineural invasion using clinical or pathological criteria: this relates to a named nerve or a nerve ≥0.1mm diameter or a nerve deeper than the dermis or tumour cells within the nerve.

Regional lymph nodes (pN)

The division between non-head and neck and head and neck (trunk and limbs) regions anteriorly represents the level of the acromioclavicular joint and posterior the level of the upper margin of the shoulder blade.

Table A.1 Carcinoma of the skin (essentially limbs and trunk but excluding the eyelid, vulva, penis or perianal area)

pNX Regional lymph nodes cannot be assessed
pN0 No regional lymph node metastasis
pN1 Metastasis in a single ipsilateral lymph node ≤30mm in greatest dimension
pN2 Metastasis in a single ipsilateral lymph node >30mm, but not more than 60mm in greatest dimension, or in multiple ipsilateral lymph nodes, but not more than 60mm in greatest dimension
pN3 Metastasis in a lymph node >60mm in greatest dimension

A contralateral nodal metastasis (unlike with skin carcinoma of head and neck below) represents a distant metastasis.

There is an expectation that at least six lymph nodes will be identified in a lymphadenectomy specimen.

Table A.2 Skin carcinoma of head and neck (excluding vermillion lip)

pNX Regional lymph nodes cannot be assessed
pN0 No regional lymph node metastasis
pN1 Metastasis in a single ipsilateral lymph node ≤30mm in greatest dimension, without extranodal extension
pN2a Metastasis in a single ipsilateral lymph node, more than 30mm but not more than 60mm in greatest dimension, without extranodal extension
pN2b Metastasis in multiple ipsilateral lymph nodes, none more than 60mm in greatest dimension, without extranodal extension
pN2c Metastasis in bilateral or contralateral lymph nodes, none more than 60mm in greatest dimension, without extranodal extension
pN3a Metastasis in a lymph node, more than 60mm in greatest dimension, without extranodal extension
pN3b Metastasis in a lymph node with extranodal extension

Extranodal extension can be defined by clinical or pathological criteria.

There is an expectation that at least 10 lymph nodes will be identified by selective lymphadenectomy and at least 15 in radical or modified radical lymphadenectomy.

Table A.3 Distant metastasis (M)

M0 No distant metastasis
M1/pM1 Distant metastatic disease

Note: MX and pM0 do not exist.

Table A.4 Staging group

Stage 0 Tis N0 M0
Stage I T1 N0 M0
Stage II T2 N0 M0
Stage III T3 N0 M0
  T1, T2, T3 N1 M0
Stage IVA T1, T2, T3 N2, N3 M0
T4 Any N M0
Stage IVB Any T Any N M1

References

  1. Skin Tumours In: Brierley JD, Gospodarowicz MK, Wittekind C (eds).. TNM Classification of Malignant Tumours (8th edition). Oxford, UK: Wiley-Blackwell; 2017.

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