Small Intestine
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Small Intestine (ICD‐O‐3 C17) Rules for Classification The classification applies only to 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, imaging, endoscopy, and/or surgical exploration N categories Physical examination, imaging, and/or surgical exploration M categories Physical examination, imaging, and/or surgical exploration
Anatomical Subsites
Note This classification does not apply to carcinomas of the ampulla of Vater (see page 91).
Regional Lymph Nodes The regional lymph nodes for the duodenum are the pancreaticoduodenal, pyloric, hepatic (pericholedochal, cystic, hilar), and superior mesenteric nodes. The regional lymph nodes for the ileum and jejunum are the mesenteric nodes, including the superior mesenteric nodes, and, for the terminal ileum only, the ileocolic nodes including the posterior caecal nodes.
TNM Clinical Classification T – Primary Tumour TX Primary tumour cannot be assessed T0 No evidence of primary tumour Tis Carcinoma in situ
Digestive System
1. Duodenum (C17.0) 2. Jejunum (C17.1) 3. Ileum (C17.2) (excludes ileocecal valve C18.0)
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Digestive System Tumours
T1 Tumour invades lamina propria, muscularis mucosae or submucosa T1a Tumour invades lamina propria or muscularis mucosae T1b Tumour invades submucosa T2 Tumour invades muscularis propria T3 Tumour invades subserosa or non‐peritonealized perimuscular tissue (mesentery or retroperitoneum*) without perforation of the serosa T4 Tumour perforates visceral peritoneum or directly invades other organs or structures (includes other loops of small intestine, mesen tery, or retroperitoneum and abdominal wall by way of serosa; for duodenum only, invasion of pancreas) Note * The non‐peritonealized perimuscular tissue is, for jejunum and ileum, part of the mesentery and, for duodenum in areas where serosa is lacking, part of the retroperitoneum.
N – Regional Lymph Nodes NX N0 N1 N2
Regional lymph nodes cannot be assessed No regional lymph node metastasis Metastasis in 1 to 2 regional lymph nodes Metastasis in 3 or more regional lymph nodes
M – Distant Metastasis M0 No distant metastasis M1 Distant 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 6 or more lymph nodes. If the lymph nodes are negative, but the number ordinarily examined is not met, classify as pN0.
Small Intestine
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Stage Tis T1, T2 T3 T4 Any T Any T Any T
N0 N0 N0 N0 N1 N2 Any N
M0 M0 M0 M0 M0 M0 M1
Digestive System
Stage 0 Stage I Stage IIA Stage IIB Stage IIIA Stage IIIB Stage IV