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Report Produced: 09/16/2026 16:26 PM

Report Question ID Question Discussion Answer Cancer Site Category Data Item Category Year
20200074

Solid Tumor Rules (2018)/Histology--Head & Neck: What specific table(s) in the 2021 Head and Neck Solid Tumor Rules if any, apply to tumors of the lip? See Discussion.

Lip has not been added to any of the site-specific histology tables, nor has any other instruction been provided for coding tumors in this site.

Coding histology for lip primaries is difficult because registrars do not know where to look first. The Solid Tumor Rules indicate one should use the tables first, but then do not inform registrars what table to use for a lip primary (i.e., a specific table, any table, no table).

This question was prompted from preparing SEER*Educate coding exercises. We will use the answer as a reference in the rationales.

The tables are based on WHO H&N chapters which do not include lip. There are inherent issues in determining reportability for lip primaries based on site and histology. The decision was made prior to release of the 2018 rules to exclude a histology table for lip. We are consulting both our dermatology and H&N pathology experts to explore adding a lip site-specific table to the rules.

 Head & Neck Histology 2020
20200073

Solid Tumor Rules (2018)/Histology--Colon: Should the mixed adenoneuroendocrine carcinoma (MANEC) row in Table 1 include the still often used (yet older) terms of adenocarcinoma and carcinoid, adenocarcinoid, etc. for clarity? See Discussion.

The Terms and Definitions Introduction discusses how these are older terms, but pathologists may still use them. In our region, pathologists do, in fact, still use these terms. Can these terms be added to Table 1? For registrars who do not reference the Introduction every time they code histology but go directly to Table 1, coding consistency would likely improve if such terms were added in the Table.

This question was prompted from preparing SEER*Educate coding exercises. We will use the answer as a reference in the rationales.

The next update to the Solid Tumor rules will include adding the following four terms to Colon Table 1 as synonyms for Mixed adenoneuroendocrine carcinoma 8244

  • Mixed adenoneuroendocrine carcinoma

  • Combined carcinoid and adenocarcinoma

  • Mixed carcinoid and adenocarcinoma

  • Composite carcinoid

    		•  Colon Histology 2020
    		20200072

    Solid Tumor Rules (2018)/Multiple Primaries--Breast: How many primaries are accessioned when there are multiple synchronous/non-contiguous tumors when one tumor is metaplastic carcinoma (with carcinoma No Special Type (NST) or lobular carcinoma) and another tumor is strictly carcinoma, NST? See Discussion.

    Is an M rule needed to address multiple tumors and Note 2 in Table 3? Does Note 2 in Table 3 apply when multiple tumors exist and one tumor contains only ductal carcinoma?

    The M Rules currently confirm that a metaplastic carcinoma (whether it is involved with ductal or lobular) and a separate ductal carcinoma are separate primaries because these histologies are on different rows in Table 3 (separate primaries per M14). There is no specific rule regarding metaplastic carcinomas in the Multiple Tumors (M Rules) module, so presumably, the presence of a separate ductal carcinoma is not lumped into Note 2 in Table 3 for metaplastic carcinoma.

    However, the note is confusing when there are multiple tumors involved because it appears to the registrars there are two options for coding the histology. To some registrars, the rules indicate it does not matter if the tumor is predominantly ductal carcinoma as long as some percentage of metaplastic carcinoma is present, code histology to metaplastic carcinoma. For other registrars, the presence of solely a ductal carcinoma in a second tumor is a separate primary from the separate metaplastic carcinoma.

    The M rules and Note 2 need to clarify this issue to promote consistency.

    This question was prompted from preparing SEER*Educate coding exercises. We will use the answer as a reference in the rationales.

    The term "mixed" implies a single tumor comprised of metaplastic carcinoma or variants of metaplastic and duct or lobular. The metaplastic histology is coded regardless of whether it comprises the majority (greater than 50% of the tumor). M13 is the only rule specific to metaplastic and is in the single tumor module. This implies a single tumor with both histologies. When there are multiple tumors, one with metaplastic or a subtype/variant of metaplastic and another with a histology listed on a different row, continue to the Multiple Tumors module. M13 applies and there are two primaries. We will add "single tumor" to the note in Table 2 in the next update.

    		 Breast N/A 2020
    		20200071

    Solid Tumor Rules (2018)/Histology--Breast: Rule H13 of the 2021 Breast Solid Tumor Rules (a new H Rule added in the December 2020 revision) indicates metaplastic carcinoma is coded when both metaplastic carcinoma and carcinoma No Special Type (NST) are present. Should Rule H13 also address lobular carcinoma so the histology for a single tumor with metaplastic carcinoma and lobular carcinoma is correctly coded to metaplastic carcinoma (8575)? See Discussion.

    Rule H13 states to code the histology to metaplastic carcinoma when there is metaplastic carcinoma (or a subtype/variant) and invasive carcinoma NST. This rule makes no mention of lobular carcinoma. However, in Table 3, Note 2 for metaplastic carcinoma (8575) states metaplastic carcinoma, NOS and subtypes are almost always mixed with invasive mammary carcinoma, NST and at times lobular carcinoma. These tumors should be coded to metaplastic regardless of percent invasive mammary carcinoma or lobular carcinoma present.

    While Table 2 (the mixed histology code table) does include an entry for metaplastic carcinoma AND carcinoma NST OR lobular carcinoma, it is unclear why lobular carcinoma has not been added to Rule H13 as well.

    If a single tumor has metaplastic plus lobular carcinoma, Rule H13 does not apply and one has to continue through the rules. Unfortunately, the next rule registrars would be tempted to use is Rule H18: Code the histology that comprises greater than 50% of tumor when two histologies are on different rows in Table 3. This Rule does not state it does NOT apply to metaplastic carcinoma (only mucinous). So, if for some reason the lobular was greater than 50%, the incorrect histology would be coded (unless the registrar happened to remember Note 2 in the metaplastic carcinoma entry in Table 3).

    This question was prompted from preparing SEER*Educate coding exercises. We will use the answer as a reference in the rationales.

    Lobular carcinoma was unintentionally excluded from M13. It will be added in the 2022 update. It is important registrars learn to use the tables and read the notes.

    		 Breast Histology 2020
    		20200070

    Solid Tumor Rules (2018)/Multiple Primaries--Breast: The December 2020 revision to 2018 Breast Solid Tumor Rules, Rule M10, using behavior rather than timing to determine the number of primaries, has caused synchronous separate/non-contiguous tumors reported as invasive carcinoma, NST (8500/3) and lobular carcinoma in situ (8520/2) (or vice versa) to be reported as separate primaries per Rule M14. Should an invasive carcinoma NST and a synchronous, separate lobular carcinoma in situ be separate primaries per M14? See Discussion.

    Recognizing the addition of the behavior requirement into this rule is an attempt to stop non-synchronous ductal carcinoma and lobular carcinomas from being accessioned as a single primary (SINQ 20200022), the issue with using behavior rather than timing is that now, synchronous separate/non-contiguous tumors that are invasive carcinoma NST (8500/3) and lobular carcinoma in situ (8520/2) (or vice versa) are separate primaries per M14.

    Lobular and carcinoma, NST are separate rows in Table 3, so we cannot stop at M10 and code the mixed histology because there are two separate histologies with different behaviors. There is no rule that states we can just ignore the in situ tumors for the purpose of applying the M Rules. (We are instructed to ignore the in situ when coding histology only in certain circumstances.) The problem with Rule M10 appears to be related to timing.

    This question was prompted from preparing SEER*Educate coding exercises. We will use the answer as a reference in the rationales.

    The original issue with M10 was with registrars being instructed that multiple in situ and invasive tumors were a single primary and then coding 8522/3 when one tumor was in situ and one was invasive. This incorrectly identified both components as being malignant (/3). Our effort to correct this misconception apparently did not work. M10 has been revised to state that yes, an in situ lobular or duct plus an invasive lobular or duct is a single primary with a new note that states: When a mixture of behaviors is present in carcinoma, NST, and lobular carcinoma, follow the H rules to determine the correct histology code. They will stop at H8 which instructs them to code the invasive histology. 8522/3 should only be used when both components are invasive.

    		 Breast N/A 2020
    		20200069

    Solid Tumor Rules (2018)/Histology--Breast: What histology code is used for an in situ encapsulated papillary carcinoma with an invasive carcinoma, NST? See Discussion.

    In Table 3 (Specific Histologies, NOS/ NST, and Subtypes/Variants), the entry for papillary carcinoma, NOS includes a change in column 3 of the 2018 Breast Solid Tumor Rules that conflicts with the H Rules. It is not accounted for in the change log. No explanation is offered as to why this change was made. This is a major change because encapsulated papillary carcinoma is frequently associated with carcinoma NST, and we have not been collecting these as such.

    Encapsulated papillary carcinoma (8504) in column 3 now includes an indented entry, with invasive carcinoma, NST/invasive duct carcinoma 8504/3. However, most encapsulated papillary carcinomas are in situ or there is no definitive statement of invasive encapsulated papillary carcinoma, so when in situ and invasive tumors are present, we are instructed to code the invasive histology (which would be the invasive carcinoma (NST), 8500/3). How are registrars to arrive at the correct histology without a new H rule or a clarification regarding this update being documented in the change log?

    Does the same change/addition apply to solid papillary carcinoma? These are often also associated with carcinoma, NST. Again, without an explanation regarding the change mentioned above, it is difficult to understand why the change was made.

    This question was prompted from preparing SEER*Educate coding exercises. We will use the answer as a reference in the rationales.

    In situ encapsulated papillary arising in or with invasive carcinoma, NST (a single tumor) is a single invasive histology. Use rule H14 and code the histology per Table 3.

    A note as been added to the 2023 breast rule H8 instructing when there is a single tumor with histology of in situ encapsulated papillary with invasive carcinoma or solid papillary carcinoma with invasove, continue through the rules. See H14 and code the appropriate histology per Table 3.

    Histologic types are becoming more complex and often have both in situ and invasive components but have a single code to identify them.

    		 Breast Histology 2020
    		20200068

    Summary Stage 2018/Extension--Colon: Are colon primaries coded as local or regional (direct extension) on Summary Stage based on invasion into the pericolorectal tissues? For example, is a case with an ascending colon tumor that extends into the pericolorectal tissues, pT3, local or regional by direct extension?

    Code as Localized using the SEER Summary Stage Manual, Colon and Rectum, Note 6.

    Localized is for subsites that are not peritonealized, including the posterior side of the ascending colon, or when the pathologist does not further describe the "pericolic/perirectal tissues" as either "non-peritonealized pericolic/perirectal tissues" vs "peritonealized pericolic/perirectal tissues" fat and the gross description does not describe the tumor relation to the serosa/peritoneal surface, and it cannot be determined whether the tumor arises in a peritonealized portion of the colon.

    Refer to the coding instructions in both EOD and Summary Stage for a list of sites that are nonperitonealized or peritonealized.

    .

    		 Colon N/A 2020
    		20200067

    Summary Stage 2018/Extension--Colon: What is the Summary Stage for adenocarcinoma of cecum where the tumor extends into the proximal portion of attached vermiform appendix? See Discussion.

    2020 Diagnosis: Patient had a right hemicolectomy showing adenocarcinoma of cecum, tumor extends into proximal portion of attached vermiform appendix. Tumor invades through muscularis propria into pericolorectal tissues (NOS). Regional lymph nodes: 06/39. Primary Tumor EOD: Where does the appendix involvement come into coding or will this be based on the pericolorectal tissue (NOS) invasion? What is my Summary Stage? I know it is at least 3 due to regional ln involvement, but the appendix involvement is making me question 3 vs 4.

    Assign code 4, Regional by BOTH direct extension AND regional lymph node(s) involved. In this case, the Regional component for Summary Stage 2018 is based on Note 6, under Colon and Rectum where Regional is defined as:

    -Mesentery

    -Peritonealized pericolic/perirectal tissues invaded [Ascending Colon/Descending Colon/Hepatic Flexure/Splenic Flexure/Upper third of rectum: anterior and lateral surfaces; Cecum; Sigmoid Colon; Transverse Colon; Rectosigmoid; Rectum: middle third anterior surface]

    -Pericolic/Perirectal fat

    		 Colon N/A 2020
    		20200066

    Reportability--Skin: Effective 2021, a cutaneous leiomyosarcoma is a related term for smooth muscle tumor, NOS (8897/1) in ICD-O-3.2. Currently, we have been capturing these as a C44_ (leiomyosarcoma, 8890/3) but the 2019 SEER inquiry states that atypical intradermal smooth muscle neoplasm (AISMN) was previously termed cutaneous leiomyosarcoma. This is not documented on the 2018 ICD-O-3 updates. Should this 2019 case be 8897/1 or 8890/3?

    Cutaneous leiomyosarcoma is reportable for 2019. Code histology to leiomyosarcoma 8890/3.

    As of cases diagnosed 1/1/2021, it is no longer reportable based on assignment to 8897/1 in ICD-O-3.2.

    		 Skin N/A 2020
    		20200065

    Tumor Size/Corpus uteri--Endometrium: Is clinical tumor size coded to the endometrial stripe measurement or thickening in the endometrium. See Discussion.

    Example: Pelvic ultrasound-19 mm thickened endometrium; bilateral ovaries unremarkable. Case was coded to 19 mm for clinical tumor size. I have always been taught NOT to use "endometrial stripe" or "thickening" measurements for clinical size. Can you confirm. Also, is this noted on any of the SEER resources such as SEER training or in the SEER tumor size guidelines? I wanted to point them out to a reference if it is available.

    We consulted with an expert GYN pathologist. He confirmed our thinking that endometrial stripe or thickening does not represent clinical tumor size. We will add this to a future edition of the SEER manual for reference.

    		 Corpus uteri Tumor size 2020