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Table 4 (Changes in reportable terminology), 2021 ICD-O-3.2 Update, does confirm that the term malignant no longer needs to be used to describe a paraganglioma, but Table 4 includes the histology for extra-adrenal paraganglioma, NOS (8693/3) as the new preferred term for paraganglioma. Paraganglioma, NOS is histology code 8680/3. Which code is correct?

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

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.

Per Mayo consulting pathologist, the final diagnosis on this right lung biopsy is: SMARCA4-deficient malignant neoplasm (see Comment). Comment: Sections show a poorly-differentiated malignant neoplasm without any apparent glandular, squamous, or stromal differentiation. The tumor near totally replaces the underlying lung tissue without recognizable underlying alveolar parenchyma. Immunohistochemical stains performed at Mayo Clinic (Oscar keratin, INSM1, NUT, S100, desmin and BRG1 protein encoded by SMARCA4 gene) demonstrate that the malignant cells are positive for Oscar keratin (rare cells only), synaptophysin (weak/patchy) and p63 (focal) while negative for the remaining antibodies tested. Of note, SMARCA4 stain is negative in the tumor cells. Thus, this tumor can be categorized as a SMARCA4-deficient malignant neoplasm, which is known to be an aggressive malignancy, likely represent a SMARCA4-deficient thoracic sarcoma, a recently described entity. SMARCA4-deficient carcinomas in the lung have been reported to be mostly adenocarcinomas or squamous cell carcinomas, which would not fit for this case. Please refer to a paper published by our group (Sauter JL et al. Mod Pathol 2017;30:1422-32.

Example: Patient is found to have a 9.4 cm GIST in the jejunum and 2 cm GIST in the stomach during resection, neither stated to be outright malignant. Similar to the instruction in SINQ 20190041, this case is coded as a malignant jejunal primary due to multifocal tumor. However, it is unclear how to account for the stomach tumor, or any other multifocal tumor for GIST, when coding EOD and Summary Stage.

For example, chemotherapy and immunotherapy administered first, followed by surgery, then immunotherapy and hormone therapy after surgery. Or is code 4 used for two administrations of chemotherapy before surgery and two more courses after surgery?

Per the site validation list: https://seer.cancer.gov/icd-o-3/sitetype.icdo3.20190618.pdf#search=site%20validation, ill-defined sites (ILL-DEFINED C760-C768) does not include 8070- Squamous cell carcinoma as a valid histology. Therefore when a Cervical Lymph Node and Unknown Primary Tumor of the Head and Neck is submitted with a C760 and 8070/3, it requires an override be set.

Should histology be coded as paraganglioma, NOS (8680/3) or as extra-adrenal paraganglioma, NOS (8693/3) for a diagnosis of paraganglioma in the bladder? Does the pathologist have to specifically diagnose the tumor as extra-adrenal paraganglioma, NOS to use histology code 8693/3? Or, does any diagnosis of paraganglioma (NOS) arising outside of the adrenal gland, carotid body, middle ear, or aortic body (the specified sites for other types of paragangliomas) qualify as an extra-adrenal paraganglioma, NOS?

The ICD-O-3.2 Implementation Guidelines (Tables 6 and 7) provide an associated site of C755 for histology 8680/3 (paraganglioma, NOS), but no associated site code is provided for histology 8693/3 (extra-adrenal paraganglioma, NOS). If the preferred site for paraganglioma, NOS is the paraganglia, would a paraganglioma in the bladder be an extra-adrenal paraganglioma?

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.

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.

Lung Rule M14 appears to be the first rule that applies to this case and instructs the user to abstract a single primary. However, we were hoping for confirmation that a cancer (NOS) or malignancy (NOS) would not be a distinctly different histology that may qualify for Lung Rule M8. Currently, these histologic terms are not included in the Table 3 options or mentioned in the preceding notes.