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Pituitary blastoma was not added to Table 3 (Specific Histologies, NOS, and Subtypes/Variants) of the 2018 Malignant CNS and Peripheral Nerves Solid Tumor Rules as part of the December 2020 update. This is a new malignant CNS histology for 2021 and later. Not including this histology in Table 3 results in the registrars being required to check another source to correctly code this histology. If this histology cannot be used for cases diagnosed prior to 2021, should that diagnosis year clarification be included in the STR?

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

Table 1 of the 2018 Kidney Solid Tumor Rules (STR) lists succinate dehydrogenase-deficient renal cell carcinoma as histology code 8312, but in the ICD-O-3.2 Coding Table it is listed as histology code 8311.

No changes were made in the Kidney STR. As a result, the histology change described in the ICD-O-3.2 Coding Table conflicts with Table 1. Succinate dehydrogenase-deficient renal cell carcinoma (SDHD) is listed in Table 1 as a synonym for renal cell carcinoma, NOS (8312). However, the ICD-O-3.2 Coding Table lists this as a related term for histology code 8311/3. This related term was not discussed in the Implementation Guidelines, and no change was noted in the STR.

While it seems we should continue to follow the STR, without clarification as to why this histology change was not implemented in STR, achieving consistency will be problematic if registrars jump straight to the ICD-O-3.2 Coding Table to code histology for cases diagnosed 2021 and later. If this code cannot be used for cases diagnosed prior to 2021, should that clarification be included in the STR?

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

First, reportability of clear cell papillary renal cell carcinoma changed from 8323/3 to 8323/1. Although it does not appear the standard-setters implemented this change, note of the conflict between the ICD-O-3.2 and the Solid Tumor Rules (STR) is not included in the Implementation Guidelines or STR. The current Note for clear cell papillary renal cell carcinoma (8323) was left in Table 1, so this presumably is still reportable. It would be helpful if the conflict with ICD-O-3.2 was addressed, especially since the existing Note refers to changes made back in 2016 (not 2018 or 2021).

Second, is the term sarcomatoid renal cell carcinoma still coded as a synonym for renal cell carcinoma (8312) because sarcomatoid is referring to a pattern of differentiation or 8318 (renal cell carcinoma, sarcomatoid)? The STR, Table 1, lists sarcomatoid renal cell carcinoma as 8312, but the ICD-O-3.2 lists this as 8318. The Note in Table 1 still indicates WHO/IARC and College of American Pathologists agree that sarcomatoid carcinoma is a pattern of differentiation, not a specific subtype, of renal cell carcinoma. This appears to conflict with WHO/IARC ICD-O-3.2 Coding Table as it provides a different, specific histology code for this malignancy. How can WHO/IARC classify this both a pattern of renal cell carcinoma and a separate, specific histology?

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

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 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.

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.

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.

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.

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.