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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.

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 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.

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.

The ICD-O-3.2 Implementation Guidelines and ICD-O-3.2 Coding Table indicate that insulinoma, NOS has changed behavior from /0 to /3 for cases diagnosed 2021 and later. However, the ICD-O-3.2 Implementation Guidelines do not indicate whether this change applies to tumors described as above. Insulinomas are generally neuroendocrine tumors/neoplasms, so it seems any neuroendocrine tumor described as an insulinoma should be collected as 8151/3, but does that apply to an epithelioid tumor/neoplasm also described as insulinoma?

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

In the 2018 ICD-O-3 Update Table, undifferentiated high-grade pleomorphic sarcoma and undifferentiated high-grade pleomorphic sarcoma of bone (C40_) were both listed as a New Term for histology 8830/3. There was no site restriction for a diagnosis of undifferentiated high-grade pleomorphic sarcoma. Therefore, it appears the diagnosis could easily be applied to a soft tissue tumor. This histology is used by pathologists in our region for soft tissue tumors as well as bone tumors. However, in the ICD-O-3.2 Table an entry (or synonym) was not provided for a tumor outside the bone.

The ICD-O-3.2 Table only lists undifferentiated high-grade pleomorphic sarcoma of bone for site codes C40_ and C41_ as a synonym for histology 8830/3. This also is not listed in the ICD-O-3.2 Implementation Guidelines. As a result, it is unclear whether a diagnosis of undifferentiated high-grade pleomorphic sarcoma of the soft tissue can be coded to 8830/3 and/or can be a synonym for the preferred term (8830/3, Malignant fibrous histiocytoma). Can a diagnosis of undifferentiated high-grade pleomorphic sarcoma of the soft tissue be coded to 8830/3, C49_ as it was per the 2018 ICD-O-3 Update Table?

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

While we recognize the Heme DB has been the correct source for histology coding for heme and lymphoid neoplasms dating back to 2010, the ICD-O-3.2 Implementation Guidelines appear to provide incorrect coding instructions. Histologies 9670/3, 9728/3, 9729/3 and 9836/3 are listed in Table 3 - Deleted ICD-O codes in ICD-O-3.2.

While we recognize these histologies have been included in this Table because they have now been deleted, it is unclear whether the Comments regarding their use listed in the 4th column of the Table is correct. For each of these histologies, the comment states the histology listed in the 1st column (ICD-O-3/3.1) should be used prior to 2021. For example, for histology 9670/3, the comment states: Cases diagnosed prior to 1/1/2021 use code 9670/3. Cases diagnosed 1/1/2021 forward use code 9823/3. However, each of these histology codes have been obsolete for cases diagnosed 1/1/2010 and later. If registrars were following the Heme DB and Heme Manual instructions (the appropriate coding source for these neoplasms), these histologies would not have been used in a decade.

Should the Comments column in Table 3 be updated? Or should a Note follow the Table indicating registrars should not use these histology codes for cases diagnosed after 1/1/2010, and these histology codes have been deleted for cases diagnosed 1/1/2021? It seems misleading to indicate any of these are valid histology codes for a 2010-2020 diagnosis when the Heme DB confirms these histology codes only apply to cases diagnosed prior to 2010.

There are four invasive tumors in the right lung:

Large cell undifferentiated carcinoma in the right lower lobe (8012/3, C343);

Adenocarcinoma, acinar-predominant in the right lower lobe (8551/3, C343) that was 0.7 cm in size and limited to the lung;

Mucinous adenocarcinoma in the right upper lobe (8253/3, C341) that was 0.9 cm and limited to the lung;

Adenocarcinoma, NOS also in the right upper lobe (8140/3, C341) that was 1 cm and limited to the lung.

The Lung M Rules confirm the large cell undifferentiated carcinoma is a separate primary from the three adenocarcinoma tumors (Rule M8). The acinar adenocarcinoma and mucinous adenocarcinoma tumors are separate primaries (Rule M6). The adenocarcinoma, NOS tumor is the same primary as both the acinar and mucinous are adenocarcinomas (Rule M7).

How is Primary Site coded for both the acinar and mucinous adenocarcinomas if they represent multiple tumors reported as a single primary (when compared to the adenocarcinoma, NOS tumor)?

Should the adenocarcinoma, NOS tumor also be included when coding EOD Primary Tumor for both the right lower lobe acinar adenocarcinoma and right upper lobe mucinous adenocarcinoma primaries? Further follow-up with the physician is not possible.

Example: MRI found an intradural, extra-axial mass at T12/L1 with possible intramedullary component. Resection of the intradural intramedullary and extramedullary spinal cord tumor found a capillary hemangioma pathologically. The microscopic description on the path report describes a tumor with extensive vascularity involving the dura.

Should we equate the statement of capillary to mean the tumor is arising in a blood vessel as we do for venous hemangioma (non-reportable per SINQ 20130001)? Or should it be reportable as C700, 9131/0 because it is described as involving the dura (intradural, intramedullary and extramedullary)?

Example: An MRI Spine showed a large expansile mass arising from the sella turcica and extending into the suprasellar cistern, but the radiologist only noted: The leading differential considerations include pituitary macroadenoma or a large suprasellar base meningioma. The patient was subsequently pathologically diagnosed with a pituitary adenoma. It is unclear if the diagnosis date should be coded to the MRI date.

There are two existing SINQ questions regarding the term consider. SINQ 20061094 confirms a diagnosis that is considered to be is reportable because it is unambiguous, but SINQ 20081033 states the phrase malignancy is highly considered is not a reportable ambiguous term.

How should we interpret differential considerations? If differential considerations is equivalent to a differential diagnosis, then this patient was clinically diagnosed on imaging. However, if differential considerations is not reportable, then there was no diagnosis prior to the resection.