Small intestine & ampulla


Staging-small intestine neuroendocrine tumors

Editor-in-Chief: Debra L. Zynger, M.D.
Raul S. Gonzalez, M.D.

Last author update: 10 December 2020
Last staff update: 1 April 2024 (update in progress)

Copyright: 2003-2024,, Inc.

PubMed Search: Staging neuroendocrine tumors small bowel[TIAB]

Raul S. Gonzalez, M.D.
Page views in 2024 to date: 825
Cite this page: Gonzalez RS. Staging-small intestine neuroendocrine tumors. website. Accessed April 14th, 2024.

Pathologic TNM staging of neuroendocrine tumors of the jejunum and ileum, AJCC 8th edition
Definition / general
  • Well differentiated neuroendocrine tumors of the jejunum and ileum are covered by this staging system
  • Not covered by this staging system are well differentiated neuroendocrine tumors of the ampulla or duodenum (use ampulla staging) or poorly differentiated neuroendocrine carcinomas of the small intestine (use small bowel carcinoma staging)
ICD coding
  • C7A.011: malignant carcinoid tumor of the jejunum
  • C7A.012: malignant carcinoid tumor of the ileum
Primary tumor (pT)
  • TX: primary tumor cannot be assessed
  • T0: no evidence of primary tumor
  • T1: invades lamina propria or submucosa and ≤ 1 cm in size
  • T2: invades muscularis propria or > 1 cm in size
  • T3: invades through the muscularis propria into subserosal tissue without penetration of overlying serosa
  • T4: invades visceral peritoneum (serosa) or other organs or adjacent structures
Regional lymph nodes (pN)
  • NX: regional lymph nodes cannot be assessed
  • N0: no regional lymph node metastasis
  • N1: regional lymph node metastasis in < 12 nodes
  • N2: large mesenteric masses (> 2 cm) or extensive nodal deposits (≥ 12), especially those that encase the superior mesenteric vessels

  • Regional lymph nodes include superior mesenteric and mesenteric nodes; posterior cecal nodes also apply for terminal ileum lesions
  • 2 cm cutoff for including mesenteric masses in N categorization may be suboptimal (Mod Pathol 2018 May 24 [Epub ahead of print])
Distant metastasis (pM)
  • M0: no distant metastasis
  • M1: distant metastasis
    • M1a: metastasis confined to liver
    • M1b: metastasis in at least one extrahepatic site (e.g., lung, ovary, nonregional lymph node, peritoneum, bone)
    • M1c: both hepatic and extrahepatic metastasis
  • (m): multiple primary lesions (provide stage for the most advanced lesion)
  • r: recurrent tumor stage
Stage grouping
  • Stage I:T1 N0 M0
  • Stage II:T2 - 3 N0 M0
  • Stage III:T4 N0 M0
  • any T N1 - 2 M0
  • Stage IV:any T any N M1

Registry data collection variables
  • Size of tumor (value or unknown)
  • Tumor focality (unifocal or multifocal)
  • Depth of invasion
  • Nodal status and number of nodes involved, if applicable
  • Sites of metastasis, if applicable
  • NKA (neurokinin A) level
  • Pancreastatin level
  • Ki67 index
  • Mitotic count
  • Histologic grading (from Ki67 and mitotic count): G1, G2, G2
Histologic grade
  • Grading is not formally part of the staging system
  • Most pathologists use the European Neuroendocrine Tumor Society (ENETS) / WHO grading criteria:
    • Grade 1: mitotic rate < 2 per 10 high power fields and Ki67 rate < 3%
    • Grade 2: mitotic rate 2 - 20 per 10 high power fields or Ki67 rate 3 - 20%
    • Grade 3: mitotic rate > 20 per 10 high power fields or Ki67 rate > 20%
Histopathologic type
  • Neuroendocrine tumor (NET) G1 (carcinoid)
  • Neuroendocrine tumor (NET) G2
Board review style question #1
A patient undergoes resection for jejunal neuroendocrine tumors. Three tumors are present – one smaller than 1 cm, one larger than 1 cm and invading the muscularis propria and one larger than 1 cm and invading the subserosa. Using AJCC 8th edition criteria, how would the pathologic T category be reported for this patient?

  1. Separate complete staging for each primary focus
  2. pT1/T2/T3
  3. pT1(1)T2(1)T2(1)
  4. pT3(m) or pT3(3)
Board review style answer #1
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