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In the April 2019 Breast Solid Tumor Rules update, the Priority Order for Using Documentation to Identify Histology was changed, giving equal priority to the Final diagnosis / synoptic report as required by CAP (item 2B).

There are technically two histologies documented for the case above; a Not Otherwise Stated (NOS)/No Special Type (NST) (invasive mammary carcinoma, per final diagnosis text) and subtype/variant (invasive cribriform carcinoma, per CAP report). If we do not use the synoptic report with priority over the final diagnosis, Rule H14 indicates the histology would be the NOS histology (invasive mammary carcinoma) because the percentage of tumor is not given for the subtype. However, SINQ 20180045 states, In the CAP protocol, the term Histologic Type is a label where the histology that corresponds to the largest carcinoma is collected. According to the CAP protocol for invasive breast cancer, the histologic type corresponds to the largest carcinoma.

If the pathologist summarizes the findings in a synoptic report, should the specific Histologic Type identified have priority?

In the April and July 2019 updates to the Solid Tumor Rules, the term simultaneous and Note 1 indicating histologies must be the same behavior were removed from rule M10 (ductal and lobular are a single primary).

We would like to confirm that rule M10 is the correct rule to apply to this case. This case is an invasive diagnosis approximately 4.5 years after an in situ diagnosis, so it seems like M17 should apply (invasive tumor following an in situ tumor more than 60 days later are multiple primaries).

An invasive tumor following an in situ tumor more than 60 days later of the same histology is a new primary. Similarly, it seems like an invasive tumor following an in situ tumor more than 60 days later of different histologies should be a new primary.

In the case of two or more simultaneously diagnosed primary tumors, instructions in the SEER manual state that the tumor with the worse prognosis is to be assigned the lower sequence number. Prognosis decisions should be based on primary site, histology and extent of disease.

Stage as a criteria for decision making is fairly straightforward. On the other hand, decisions based on primary site seem to be more subjective than objective.

In the Collaborative Stage manual in general instructions this guideline exists:

"The extent of disease may be described only in terms of T (tumor), N (node), and M (metastasis) characteristics. In such cases, assign the code in the appropriate field that corresponds to the TNM information. If there is a discrepancy between documentation in the medical record and the physician's assignment of TNM, the documentation takes precedence..." (Similar to language to use SEER information over TNM).

In the examples below, are these a single or multiple primaries?

Example 1:

Tumor 1:  C509/left breast, 8520/2 (in situ lobular carcinoma), dx date-01/10/2019

Tumor 2:  C509/ left breast, 8500/3 (carcinoma NST), dx date-08/19/2021

Example 2:

Tumor 1:  C509, right breast, 8520/2, dx date 06/26/2014

Tumor 2:  C508, right breast, 8500/3, dx date-05/23/2019

There seems to be some conflicting info on this. In the 2020 Breast Rules there was a note add to the revision history. “M10 Same behavior requirement re-added.” Which is not in the rules now, nor was it noted to the revision changes in the last two change logs.

Inquiry 20200070 would seem to indicate that this is multiple primaries, but that contrasts with 20230010 which would seem to indicate a single primary, and an ASK A SEER Registrar question that we received a response to. I don’t see a scenario where rule M17, an invasive tumor DX more than 60 days after an in situ tumor would come into play.

If behavior no longer applies to rule M10, at what point did that change get made? Please advise.

In the Hematopoetic Manual, page 22, it is states: "The use of donor leukocyte infusions for treatment of hematopoietic neoplasms, specifically leukemias, is increasing.  Abstract as bone marrow transplant when a reportable hematopoietic neoplasm is treated with donor leukocyte infusion, even if it is not listed in the treatment section of the Heme db for the specific neoplasm."  Question 20110048 in the SEER Inquiry, it is stated "Donor lymphocyte infusion (DLI) is coded as immunotherapy."  Donor lymphocyte infusion and donor leukocyte infusions are the same procedure.  Please clarify discrepancy as coding is needed for a case treated with donor lymphocytic infusion.

In the Heme Manual it indicates one is to abstract a second primary when a solitary plasmacytoma (chronic) is followed by a plasma cell myeloma (acute) greater than 21 days after the chronic diagnosis.

The Heme Manual does not indicate what to do when a solitary plasmacytoma diagnosed in 2010 (T spine) is followed by another solitary plasmacytoma (L spine, different primary site) in 2013. The physician specifically stated the patient does not have multiple myeloma. Is this case one or two primaries?

In the Heme Manual, published October 2025, the ambiguous terminology used to determine reportability for heme and lymphoid neoplasms (Case Reportability Instructions) was updated and "consistent with" was removed. However, this is an ambiguous term that is used to describe reportability (and not just histology). The term "consistent with" was previously included as a reportable ambiguous term used to report cases prior to this update.

The updated Heme Manual is clear regarding "consistent with" now being a definitive diagnosis for the purpose of coding histology. However, the Note under instruction 4 states, "Do not apply these changes to casefinding, reportability, or staging." Is "consistent with" an exception to this Note? Or should it be re-added to the ambiguous terms related to reportability?

In the ICD-O-3, pseudomyxoma peritonei has a behavior code of 6, indicating that it is malignant. Does this imply that pseudomyxoma peritonei is always a reportable malignancy? In the past, our pathologist consultant told us that pseudomyxoma peritonei is only a reportable malignancy if the underlying tumor is malignant. A benign cystadenoma of the appendix, for example, can rupture causing pseudomyxoma perionei. Does SEER agree with our pathologist consultant?

Example: Patient was found to have psuedomyxoma peritonei. Right hemicolectomy was done. Path reported an appendix with mucinous cystic tumor of undetermined malignant potential. A definite diagnosis of cancer can not be rendered.

In the NAACCR Coding Pitfalls 2023 webinar, the example of DCIS, solid type is given. The webinar advised us to code 8230/2 (ductal carcinoma in situ, solid type). When going through the beginning of the solid tumor rules in the Changes from 2007 MPH Rules section it states "DCIS/Carcinoma NST in situ has a major classification change. Subtypes/variant, architecture, pattern, and features ARE NOT CODED. The majority of in situ tumors will be coded to DCIS 8500/2." In the equivalent or equal terms section it lists "Type, subtype, variant" can be used interchangeably.

Since the example has it listed as as ductal carcinoma in situ, solid "type," would we code 8500/2 or 8230/2?