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SEER Inquiry System - Report
Produced: 01/21/2026 4:33 AM
Question 20100066
Inquiry Details
References:
2010 SEER Manual. Appendix C
Question:
Discussion:
If a patient has two masses in the same breast with different histology codes and different sizes, should this be accessioned as two primaries? Or should this be a single primary based on the largest tumor size or numerically higher histology code?
- Size 1.7 cm for the largest tumor size, but histology is colloid carcinoma. Histology code: 8480/3.
Answer:
For cases diagnosed 2007 or later, abstract this case as two primaries.
Mucinous/colloid carcinoma of the breast is rare. The first tumor describes (1.7 cm) fits this criteria because the pathologist simply says mucinous carcinoma. The diagnostic criteria for mucinous carcinoma is that pools of extracellular mucin make up at least 1/3 of the volume throughout the tumor mass. If focal areas are not at least 33% mucinous, the designation is a mixed mucinous/ductal. That fits the second tumor (1.5 cm).
For this case, you must get the histology codes for both tumors in order to use the Multiple Primary rules. Per H14 the first tumor is coded mucinous carcinoma [8480/3]. Per H17 the second tumor is coded duct carcinoma mixed with any other carcinoma [8523/3]. Now go to the MP rules. Per M12 abstract this case as multiple primaries because the ICD-O-3 histology codes are different at the second and third digit.
