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SEER Inquiry System - Report
Produced: 07/22/2025 8:53 PM
Question 20150010
Inquiry Details
References:
2007 MP/H Rules
Question:
Multiple Primaries/Histology--Colon: What is the correct histology code and MP/H Rule when a colectomy final diagnosis is adenocarcinoma with colloid and signet ring cell features? See discussion.
Discussion:
The MP/H Equivalent Terms and Definitions for Colon indicate that type, subtype, predominantly, with features of, major, or with ___ differentiation are all equivalent in terms of coding histology. However, this is not indicated in the General Instructions (e.g., Histologic Type ICD-O-3 or General Instructions Histology Coding Rules). It also is not included as a Note under the Rules where one would expect to use these terms, for example, Rule H7. Is this an oversight or error in the Manual?
In this case, Rule H7 seems to be the first (and most appropriate) rule that applies to this mixed histology tumor. However, the specific histology terms that an invasive tumor may be identified as, are only listed under Rule H13. Can these same terms be used when applying rules for which they are not specifically noted? It would seem logical to use the equivalent histology terms to code a mixed histology tumor identified as a subtype or with features, etc., despite the fact that the specific terms are not listed under Rule H7.
Answer:
Rule H7 applies. Assign code 8255. H13 does not apply as mucinous/colloid/signet are not NOS histologies. They are specific histologies. This will be addressed in the upcoming revisions to the rules.
