Appendix
General
Staging-neuroendocrine tumors
Last author update: 6 May 2024
Last staff update: 6 May 2024
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Staging of appendix neuroendocrine tumors
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Cite this page: Gonzalez RS. Staging-neuroendocrine tumors. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/appendixstagingneuroendocrine.html. Accessed November 28th, 2024.
Definition / general
- All well differentiated neuroendocrine tumors of the appendix, regardless of grade, are covered by this staging system
- Not covered by this staging system are appendiceal adenocarcinomas, goblet cell adenocarcinomas and poorly differentiated neuroendocrine carcinomas (use the appendix carcinoma staging system instead)
Essential features
- AJCC 7th edition staging was sunset on December 31, 2017; as of January 1, 2018, use of the 8th edition is mandatory
- AJCC 9th edition was released in 2024, with minimal changes from the 8th edition
ICD coding
- ICD-10: C7A.020 - malignant carcinoid tumor of the appendix
Primary tumor (pT)
- TX: primary tumor cannot be assessed
- T0: no evidence of primary tumor
- T1: tumor ≤ 2 cm in greatest dimension
- T2: tumor > 2 cm but ≤ 4 cm in greatest dimension
- T3: tumor > 4 cm in greatest dimension or with subserosal invasion or involvement of the mesoappendix
- T4: tumor perforates the peritoneum or directly invades other adjacent organs or structures (excluding direct mural extension to adjacent subserosa of adjacent bowel) (e.g., abdominal wall and skeletal muscle)
Regional lymph nodes (pN)
- NX: regional lymph nodes cannot be assessed
- N0: no tumor involvement of regional lymph node(s)
- N1: tumor involvement of regional lymph node(s)
Notes:
- Ileocolic nodes are the regional nodes for this staging
Prefixes
- c: clinical
- p: pathological
- yc: posttherapy clinical
- yp: posttherapy pathological
Primary tumor suffix
- (m): multiple synchronous primary tumors
AJCC prognostic stage groups
| Stage I: | T1 | N0, NX | M0
|
| Stage II: | T2 | N0, NX | M0
|
| T3 | N0 | M0
|
| Stage III: | T4 | N0 | M0
|
| any T | N1 | M0
|
| Stage IV: | any T | any N | M1
|
Prognostic tumor characteristics
- Ki67 index
- Mitotic count
- Plasma or urinary 5-HIAA level
- Echocardiogram (carcinoid heart disease)
Registry data collection variables
- Size of tumor
- Depth of invasion
- Invasion of mesoappendix
- Number of nodes involved, mesenteric mass, mesenteric vessel encasement
- Perineural invasion
- Lymphovascular invasion
- Sites of metastasis, if applicable
- Type of surgery
- Ki67 index
- Mitotic count
- Grade (from Ki67 and mitotic count): G1, G2, G3
- Presence of somatostatin receptor expression (usually determined by using somatostatin receptor imaging such as DOTATATE PET)
Emerging factors for data collection
- Somatostatin receptor type 2 (SSTR2) positivity
Histologic grade (G)
- G1: mitotic rate < 2 per 2 mm2 and Ki67 < 3%
- G2: mitotic rate 2 - 20 per 2 mm2 or Ki67 3 - 20%
- G3: mitotic rate > 20 per 2 mm2 or Ki67 > 20%
Histopathologic type
- Neuroendocrine tumor, NOS
- Neuroendocrine tumor, grade 1
- Neuroendocrine tumor, grade 2
- Neuroendocrine tumor, grade 3
- L cell neuroendocrine tumor
- Glucagon-like peptide producing neuroendocrine tumor
- PP / PPY (pancreatic polypeptide) producing tumor
- Enterochromaffin cell (EC cell) neuroendocrine tumor
- Serotonin producing neuroendocrine tumor
Residual tumor (operative factor)
- R0: complete resection, margins histologically negative, no residual tumor left after resection
- R1: incomplete resection, margins histologically involved, microscopic tumor remains after resection of gross disease (relevant to resection margins that are microscopically involved by tumor)
- R2: incomplete resection, margins involved or gross disease remains
Board review style question #1
Which of the following factors affect the staging of appendiceal neuroendocrine tumors?
- Ki67 index and extent of local spread
- Ki67 index and mitotic rate
- Size and extent of local spread
- Size and Ki67 index
Board review style answer #1
C. Size and extent of local spread. These are used to determine pT category staging; pT1 - pT3 include size and pT3 - pT4 include local spread. Answers A, B and D are incorrect because Ki67 index and mitotic rate are used in grading but not staging of appendiceal neuroendocrine tumors.
Comment Here Reference:
Appendix - Staging - neuroendocrine tumors Board review style question #2
An appendiceal neuroendocrine tumor develops clinical metastatic disease to the liver but no other sites. What is the cM category staging for this tumor?
- cM0
- cM1a
- cM1b
- cM1c
Board review style answer #2
B. cM1a. Metastatic disease only to the liver is considered M1a for appendiceal neuroendocrine tumors. Answer A is incorrect because it suggests there is no distant metastatic disease. Answer C is incorrect because M1b requires metastasis to nonhepatic distant sites. Answer D is incorrect because M1c requires distant metastasis to both hepatic and extrahepatic sites.
Comment Here Reference:
Appendix - Staging - neuroendocrine tumors
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