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SEER Inquiry System - Report
Produced: 01/08/2026 7:00 AM
Question 20130027
Inquiry Details
References:
#1: ICD-O-3
#2: WHO Class Digest System Tumors
Question:
Reportability--Are well-differentiated neuroendocrine tumors and grade 1 neuroendocrine tumors of the appendix now reportable? See Discussion.
Discussion:
The terminology for carcinoid tumors has changed. The current terminology used is "neuroendocrine tumor." Are well-differentiated neuroendocrine tumors of the appendix non-reportable because carcinoid, NOS of the appendix has a borderline behavior code [8240/1]? When the histology/behavior codes for the term "well-differentiated neuroendocrine tumor" became 8240/3, did SEER intend this change to also apply to appendix primaries? If so, for which diagnosis year did this change go into effect?
Answer:
Well-differentiated neuroendocrine tumors and grade 1 neuroendocrine tumors of the appendix are reportable because these tumors have a morphology code 8240/3 per the WHO Classification of Tumors of the Digestive System. However, per the ICD-O-3, carcinoid tumors of the appendix have a behavior code of /1 [borderline].
The terminology of neuroendocrine tumors is evolving and current thinking at the international level is that carcinoid/WD NET of appendix is reportable. However, reportability in the United States is based on ICD-O-3. The histology code for "Carcinoid of appendix" is 8240/1; the histology code for a carcinoids of all other primary sites is 8240/3. Until the United States adopts the proposed changes for ICD-O-3, reportability of appendix cases is as follows:
- Carcinoid
- Well-differentiated neuroendocrine tumor
- Grade 1 neuroendocrine tumor
- Well-differentiated neuroendocrine tumor/carcinoid (Pathologist uses both terms in reporting the diagnosis and does not want to choose one diagnosis over the other.)
