8_merkel

Merkel Cell Carcinoma of Skin

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Merkel Cell Carcinoma of Skin (ICD‐O‐3 C44.0‐9, C63.2) Rules for Classification

Regional Lymph Nodes The regional lymph nodes are those appropriate to the site of the primary tumour. See page 8.

TNM Clinical Classification T – Primary Tumour TX Primary tumour cannot be assessed T0 No evidence of primary tumour Tis Carcinoma in situ

T1 Tumour 2 cm or less in greatest dimension T2 Tumour more than 2 cm but not more than 5 cm in greatest dimension T3 Tumour more than 5 cm in greatest dimension T4 Tumour invades deep extradermal structures, i.e., cartilage, skeletal muscle, fascia or bone

N – Regional Lymph Nodes NX N0 N1 N2 N3

Regional lymph nodes cannot be assessed No regional lymph node metastasis Regional lymph node metastasis In‐transit metastasis without lymph node metastasis In‐transit metastasis with lymph node metastasis

Skin

The classification applies only to Merkel cell carcinomas. There should be histological confirmation of the disease.

The following are the procedures for assessing T, N, and M categories: T categories Physical examination N categories Physical examination and imaging M categories Physical examination and imaging

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Skin Tumours

Note In‐transit metastasis: a discontinuous tumour distinct from the primary lesion and located between the primary lesion and the draining regional lymph nodes or distal to the primary lesion.

M – Distant Metastasis M0 No distant metastasis M1 Distant metastasis M1a Skin, subcutaneous tissues or non‐regional lymph node(s) M1b Lung M1c Other site(s)

pTNM Pathological Classification The pT category corresponds to the T category. For pM see page 8. pN0 Histological examination of a regional lymphadenectomy specimen will ordinarily include 6 or more lymph nodes. If the lymph nodes are negative, but the number ordinarily examined is not met, clas­ sify as pN0. pNX Regional lymph nodes cannot be assessed pN0 No regional lymph node metastasis pN1 Regional lymph node metastasis pN1a(sn) Microscopic metastasis detected on sentinel node biopsy pN1a Microscopic metastasis detected on node dissection pN1b Macroscopic metastasis (clinically apparent) pN2 In‐transit metastasis without lymph node metastasis pN3 In‐transit metastasis with lymph node metastasis Note In‐transit metastasis: a discontinuous tumour distinct from the primary lesion and located between the primary lesion and the draining regional lymph nodes or distal to the primary lesion.

Merkel Cell Carcinoma of Skin

149

Clinical Stage Stage 0 Stage I Stage IIA Stage IIB Stage III Stage IV

Tis T1 T2, T3 T4 Any T Any T

N0 N0 N0 N0 N1, N2, N3 Any N

M0 M0 M0 M0 M0 M1

N0 N0 N0 N0 N1b N1a, N1a(sn) N1b, N2, N3 Any N

M0 M0 M0 M0 M0 M0 M0 M1

Stage 0 Stage I Stage IIA Stage IIB Stage IIIA Stage IIIB Stage IV

Tis T1 T2, T3 T4 T0 T1, T2, T3, T4 Any T Any T

Skin

Pathological Stage