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SEER Inquiry System - Report
Produced: 05/28/2026 8:25 AM
Question 20150001
Inquiry Details
References:
WHO Class Digest System Tumors, 126. 4th edition, 2010
Question:
Reportability/Histology: Would a histology reading "Well-differentiated neuroendocrine neoplasm" of the appendix be reportable? Since the word "tumor NOS" and "neoplasm NOS" both code to 8000, I would assume they would be interchangeable but just wanted to verify.
According to SINQ 20130027 & 20140002 a "Well-differentiated neuroendocrine tumor" of the appendix IS reportable.
Discussion:
Answer:
"Well-differentiated neuroendocrine neoplasm" of the appendix is reportable. According to the WHO classification of Digestive System Tumors, "Well-differentiated neuroendocrine neoplasm" of the appendix is synonymous with NET. WHO states on page 13 "The term 'neuroendocrine neoplasm' can be used synonymously with 'neuroendocrine tumor.'"
Neuroendocrine "tumor," or NET G1, is listed in the WHO classification as one of the malignant neoplasms of the appendix.
History:
Previous answer
The WHO classification does not list well-differentiated neuroendocrine "neoplasm" of the appendix as a malignancy. Check with the pathologist to determine if he/she is using this as a synonym for NET G1. Do not report the case if it is not possible to obtain clarification.
Neuroendocrine "tumor," or NET G1 is listed in the WHO classification as one of the malignant neoplasms of the appendix.
