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SEER Inquiry System - Report
Produced: 03/24/2026 3:15 PM
Question 20031092
Inquiry Details
References:
ICD-O-3
Question:
Histology (Pre-2007)/Multiple Primaries (Pre-2007)--Breast: How is the histology of invasive small cell carcinoma of lobular histogenesis coded?
Could high grade ductal carcinoma in situ, comedo type be a recurrence of ductal carcinoma diagnosed 18 years earlier?
Is "invasive small cell carcinoma of lobular histogenesis, high grade ductal carcinoma in situ, comedo type" one or two primaries? See Description.
Discussion:
Answer:
For tumors diagnosed prior to 2007:
According to our pathologist consultant:
Invasive small cell carcinoma of lobular histogenesis appears to be an unusual histology for a breast primary. Code it as such 8041 [Small cell carcinoma, NOS].
The 2002 lesion is most likely a new primary since the previous lesion was 18 years ago, in a different quadrant, and invasive. A comedo DCIS would probably not be asymtomatic for 18 years; an unlikely "recurrence" of an earlier ducal carcinoma.
Code "invasive small cell carcinoma of lobular histogenesis, high grade ductal carcinoma in situ, comedo type" as two primaries. Code the small cell as a separate primary (8041/3), and the DCIS separately (8501/2).
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.
