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SEER Inquiry System - Report
Produced: 06/18/2026 4:31 PM
Question 20120060
Inquiry Details
References:
#1: WHO Class Digest System Tumors
#2: 2012 SEER Manual
Question:
Discussion:
SINQ 20120035 states that well differentiated pancreatic endocrine neoplasms should be reported with histology code 8240/3. However, the pathology report provides the WHO Classification which states "uncertain behavior." Should this tumor still be reported as 8240/3?
If reportable, how is the primary site coded? The tumor arose in heterotopic pancreas (in the splenic hilum), which is pancreatic tissue found outside the usual anatomical location of the pancreas. Per the pathology report, the tumor did not invade the spleen. Should the primary site be coded to C48.1 [mesentery]? The patient is female and the coding schema for "Peritoneum for Females" would apply to the case. However, none of those CS extension codes seem to apply to this localized case.
Answer:
This case is reportable. Code the primary site to C25.9 [pancreas, NOS] and the histology to 8240/3 [neuroendocrine tumor (NET), Grade 1].
Per the 2012 SEER Manual, code the site in which the primary tumor originated. This neoplasm arose in pancreatic tissue and will behave accordingly, even though this pancreatic tissue is not located in the usual place.
Pancreatic endocrine and neuroendocrine neoplasms are essentially the same thing. However, they are described in two different WHO classifications; the endocrine classification and the digestive system classification. The digestive system classification is more recent, and is preferred by our expert pathologist consultant. The term "neuroendocrine" is to be used now, rather than "endocrine." In the pancreas, "well differentiated endocrine tumor" is synonymous with "neuroendocrine tumor (NET) Grade 1" and is coded 8240/3.
