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SEER Inquiry System - Report
Produced: 10/08/2026 8:28 AM
Question 20020020
Inquiry Details
References:
#1: Histology Coding Com Decision. 2003
#2: SEER Program Code Man, 3rd Ed, 12. Rule 5a
Question:
Multiple Primaries (Pre-2007)--Breast: When two breast tumors with two different histologies, such as duct and mucinous are diagnosed in the same breast at the same time, are they reportable as two primaries? See discussion.
Discussion:
Our rule is that multiple lesions of different histologic types are separate primaries. However, for separate tumors of duct and lobular, we report as a single primary. Since we now have a combination code for duct and other types of ca, do we report as a single primary or continue to report as separate primaries?
Answer:
For tumors diagnosed prior to 2007:
When there are two breast tumors, one mucinous, the other duct carcinoma, report as two primaries when the pathologist's opinion clearly states that there are separate primaries.
If there is no such information from the pathologist, the two tumors must be separate with clear (negative) margins to be reported as two primaries. Otherwise, report as one primary.
The ICD-O-3 combination codes are not intended to combine tumors of different histologic types.
For tumors diagnosed 2007 or later, refer to the MP/H rules. If there are still questions about how this type of tumor should be coded, submit a new question to SINQ and include the difficulties you are encountering in applying the MP/H rules.
