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The term “poorly differentiated carcinoma (NOS)” is listed as related to “undifferentiated carcinoma (NOS)” in the ICD-O 3.2. It is also listed in the Solid Tumor Rules for Urinary Table 2 (Urinary subtypes), Other Sites Table 16 (uterine corpus primaries) and Table 19 (vulvar primaries).

Are these the only sites in which one should code “poorly differentiated carcinoma (NOS)” as 8020 (undifferentiated carcinoma)?

How is histology coded if the only microscopic confirmation is from a metastatic site showing “poorly differentiated carcinoma” (NOS) or “invasive carcinoma, poorly differentiated” (NOS)?

Example 1: Primary pancreatic cancer diagnosed on imaging and confirmed with liver mets core biopsy showing “poorly differentiated carcinoma.” Immunostaining pattern was non-specific. No further workup or treatment was planned.

Other Sites - Table 11 (Pancreas Histologies) includes undifferentiated carcinoma (8020/3) as a valid histology; however, the synonyms/subtypes/variants do not mention poorly differentiated carcinoma. How should histology be coded for this case?

Example 2: Hemicolectomy with cecal tumor final diagnosis of “invasive carcinoma, poorly differentiated” and synoptic summary listing “Histologic type: Invasive carcinoma. Histologic grade: G3 of 4: poorly differentiated.”

Colorectal Table 1 (Specific Histologies and Subtypes/Variants) includes undifferentiated adenocarcinoma/carcinoma 8020 as a subtype of adenocarcinoma NOS. There is no mention of poorly differentiated in this context. How should histology be coded for this case?

The ICD-O-3.2 indicates histology 8051 only applies to diagnoses of condylomatous carcinoma and warty carcinoma made prior to 2018. For penis cases diagnosed 2018 and later, these neoplasms should be coded as 8054. This is consistent with SINQ 20200003.

However, a new Table was added to the Other Sites schema in the 2024 Solid Tumor Rules update. Table 23 lists “Verrucous carcinoma / carcinoma cuniculatum / Warty carcinoma” as histology 8051. While verrucous carcinoma is still listed under histology 8051 in the ICD-O-3.2, warty carcinoma is not.

Does Table 23 need to be updated? Or is this an error in both the ICD-O-3.2 and SINQ 20200003?

Example 4:  Esophageal biopsy with diagnosis of “focal areas suspicious for adenocarcinoma in situ.” Diagnosis on partial esophagectomy specimen “with foci of high grade dysplasia; no invasive carcinoma identified.” Do not accession the case. The esophagectomy proved that the suspicious biopsy result was false.

Appendix E2 #32 of the SEER Manual states high grade dysplasia in site other than stomach, small intestines, and esophageal primary sites are not reportable. Does this mean high grade dysplasia is reportable for esophagus primaries?

SEER Program Coding and Staging Manual: Reportability – Reportable Diagnosis List indicates pancreatic intraepithelial neoplasia (PanIN II) (C250-C259) is reportable.

However, the ICD-O-3.2 lists “Glandular intraepithelial neoplasia, grade II” and “Glandular intraepithelial neoplasia, low grade” as histology code 8148 with behavior of /0 (benign).

The patient underwent a gross total resection of the 2005 glioblastoma multiforme (9440/3). The patient was subsequently diagnosed with a 2024 diagnosis of astrocytoma, IDH-mutant, WHO grade 4 (9445/3).

Should Rule M13 apply to the new 2024 diagnosis and a new primary be accessioned because astrocytoma, IDH-mutant, WHO grade 4 is listed on a different row than glioblastoma? It is unclear whether histology 9445 should be classified as being on a different row because it is also listed as a subtype/variant for glioblastoma in Table 3. Table 3 lists histology 9445 as both “Astrocytoma, IDH-mutant, WHO grade 4” and as “Glioblastoma IDH-mutant.”

The 11/2023 lower gum tumor is a separate tumor occurring after a disease-free interval, so we know the Head and Neck Multiple Tumors Module applies. However, our staff is having difficulty applying the rules to this particular scenario with consistent results.

Is the 11/2023 SCC a non-reportable recurrence per M12, since M4 is ignored due to patient’s prior 2017 C031 (lower gum) primary, and then M6 is ignored due to patient’s prior 05/2022 C023 primary?

Or is the 11/2023 SCC a new primary per M4, since the last diagnosis was in a site differing at the third character (C03 vs C02)? If M4 does not apply due to patient's previous C03 primary, then does M6 apply since it has been more than 5 years since the previous C03 primary?

SINQ 20031110 addresses an overlapping lip lesion between skin and the vermillion border. We were instructed to go with area of greatest involvement. Case would be reportable if >50% of tumor was on the vermillion border and site would be coded to vermillion border (C00._). Often times percentage of involvement is not stated and all that is known is that the lesion overlaps skin and mucosa.

Patient was diagnosed March 2023 with a neuroendocrine tumorlet of the rectum measuring 0.8 mm via excisional biopsy during colonoscopy.

Prior SINQ 20160011 (stomach specific) indicates microcarcinoid and carcinoid tumors are reportable. Microcarcinoid is a designation for neuroendocrine tumors of the stomach when they are less than 0.5 cm. in size.

Is the current rectal tumor a reportable gastrointestinal neuroendocrine tumor if it is less than 5 mm (i.e., is a neuroendocrine tumorlet equivalent to a microcarcinoid)?