Small Intestine

TNM 7 classification

TNM 6 classification

1. 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

2. Anatomical Subsites

1. Duodenum (C17.0)
2. Jejunum (C17.1)
3. Ileum (C17.2) (excludes ileocecal valve C18.0)

Note: This classification does not apply to carcinomas of the ampulla of Vater (see here).

3. 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 cecal nodes.

4. TNM Clinical Classification

4.1. T - Primary Tumour

TX. Primary tumour cannot be assessed
T0. No evidence of primary tumour
Tis. Carcinoma in situ
T1. Tumour invades lamina propria or submucosa
T2. Tumour invades muscularis propria
T3. Tumour invades through muscularis propria into subserosa or into non-peritonealized perimuscular tissue (mesentery or retroperitoneum*) with extension 2 cm or less
T4. Tumour perforates visceral peritoneum or directly invades other organs or structures (includes other loops of small intestine, mesentery, or retroperitoneum more than 2 cm and abdominal wall by way of serosa; for duodenum only, invasion of pancreas)

4.2. N - Regional Lymph Nodes

NX. Regional lymph nodes cannot be assessed
N0. No regional lymph node metastasis
N1. Regional lymph node metastasis

4.3. M - Distant Metastasis

MX. Distant metastasis cannot be assessed
M0. No distant metastasis
M1. Distant metastasis

5. pTNM Pathological Classification

The pT, pN, and pM categories correspond to the T, N, and M categories.

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.

6. G Histopathological Grading

See definitions here.

7. Stage Grouping

Stage 0 Tis N0 M0 Stage I T1. T2 N0 M0 Stage II T3. T4 N0 M0 Stage III Any T N1 M0 Stage IV Any T Any N M1

8. Summary

Small Intestine T1 Lamina propria, submucosa T2 Muscularis propria T3 Subserosa, non-peritonealized perimuscular tissues (mesentery, retroperitoneum) ≤2 cm T4 Visceral peritoneum, other organs/structures (including mesentery, retroperitoneum) <2 cm N1 Regional