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Digestive System Tumours

Appendix (ICD‐O‐3 C18.1) Rules for Classification The classification applies to adenocarcinomas of the appendix.

Neuroendocrine carcinomas are classified separately (page 97). There should be histological confirmation of the disease and separation of ­carcinomas into mucinous and non‐mucinous adenocarcinomas.

Goblet cell carcinoids are classified according to the carcinoma scheme.

Grading is of particular importance for mucinous tumours.

The following are the procedures for assessing T, N, and M categories.

T categories Physical examination, imaging, and/or surgical exploration N categories Physical examination, imaging, and/or surgical exploration M categories Physical examination, imaging, and/or surgical exploration

Anatomical Site Appendix (C18.1)

Regional Lymph Nodes The ileocolic are the regional lymph nodes.

TNM Clinical Classification T – Primary Tumour TX T0 Tis

Primary tumour cannot be assessed No evidence of primary tumour Carcinoma in situ: intraepithelial or invasion of lamina propriaa

Tis (LAMN) Low‐grade appendiceal mucinous neoplasm confined to the appendix (defined as involvement by acellular mucin or mucinous epithelium that may extend into muscularis propria) T1 Tumour invades submucosa T2 Tumour invades muscularis propria T3 Tumour invades subserosa or mesoappendix T4 Tumour perforates visceral peritoneum, including mucinous peritoneal tumour or acellular mucin on the serosa of the

Appendix

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appendix or mesoappendix and/or directly invades other organs or structuresb,c,d T4a Tumour perforates visceral peritoneum, including mucinous peritoneal tumour or acellular mucin on the serosa of the appendix or mesoappendix T4b Tumour directly invades other organs or structures

N – Regional Lymph Nodes NX Regional lymph nodes cannot be assessed N0 No regional lymph node metastasis N1 Metastasis in 1 to 3 regional lymph nodes N1a Metastases in 1 regional lymph node N1b Metastases in 2–3 regional lymph nodes N1c Tumour deposit(s), i.e. satellites,* in the subserosa, or in non‐ peritonealized pericolic or perirectal soft tissue without regional lymph node metastasis N2 Metastasis in 4 or more regional lymph nodes Note * Tumour deposits (satellites) are discrete macroscopic or microscopic nodules of cancer in the pericolorectal adipose tissue’s lymph drainage area of a primary carcinoma that are discontinuous from the primary and without histological ­evidence of residual lymph node or identifiable vascular or neural structures.

If a vessel wall is identifiable on H&E, elastic or other stains, it should be ­classified as venous invasion (V1/2) or lymphatic invasion (L1). Similarly, if ­neural structures are identifiable, the lesion should be classified as perineural invasion (Pn1).

Digestive System

Notes a Tis includes cancer cells confined within the glandular basement membrane (intraepithelial) or lamina propria (intramucosal) with no extension through ­muscularis mucosae into submucosa. b Direct invasion in T4 includes invasion of other intestinal segments by way of the serosa, e.g., invasion of ileum. c Tumour that is adherent to other organs or structures, macroscopically, is classified cT4b. However, if no tumour is present in the adhesion, microscopically, the ­classification should be pT1, 2, or 3. d LAMN with involvement of the subserosa or the serosal surface (visceral ­peritoneum) should be classified as T3 or T4a respectively.

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Digestive System Tumours

M – Distant Metastasis M0 No distant metastasis M1 Distant metastasis M1a Intraperitoneal acellular mucin only M1b Intraperitoneal metastasis only, including mucinous epithelium M1c Non‐peritoneal metastasis

pTNM Pathological Classification The pT and pN categories correspond to the T and N categories. For pM see page 8. pN0 Histological examination of a regional lymphadenectomy specimen will ordinarily include 12 or more lymph nodes. If the lymph nodes are negative, but the number ordinarily examined is not met, classify as pN0.

Stage Stage 0 Stage 0 Stage I Stage IIA IIB IIC Stage IIIA IIIB IIIC Stage IVA IVB Stage IVC

Tis Tis(LAMN) T1, T2 T3 T4a T4b T1, T2 T3, T4 Any T Any T Any T Any T

N0 N0 N0 N0 N0 N0 N1 N1 N2 N0 N0 Any N

M0 M0 M0 M0 M0 M0 M0 M0 M0 M1a M1b M1b

Any T

Any N

M1c

G1 G2, G3, GX Any G