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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?

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?

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?

Example: 12/2023 Breast lumpectomy final diagnosis is Invasive ductal carcinoma, lymphoepithelioma-like carcinoma type. This is a single tumor with no in situ carcinoma present.

Lymphoepithelioma-like carcinoma is not listed as a subtype/variant or synonym for breast carcinoma in the Solid Tumor Rules histology tables.

2012 Total abdominal hysterectomy - bilateral salpingo-oophorectomy

Primary Site – Ovary, Right

Histology - Small-Cell Carcinoma (Hypercalcemic Type), Large-Cell Variant

2024 Total abdominal hysterectomy - bilateral salpingo-oophorectomy

Primary Site – Ovary, Left

Histology - Small-Cell Carcinoma (Hypercalcemic Type), Large-Cell Variant

We would like to confirm that the correct histology code is 9431/1 per ICD-O-3.2, as the Non-Malignant CNS Solid Tumor Manual lists the histology code as both 9431/1 (pages 301 and 303 of the combined manual), but also shows it as a synonym for 9421/1 – Diffuse astrocytoma, MYB- or MYBL1 altered (page 304).

Note 1 states that this histology is treatment-related neuroendocrine prostatic carcinoma demonstrating complete neuroendocrine differentiation or partial neuroendocrine differentiation with adenocarcinoma after androgen-deprivation therapy (ADT). Conversely, Note 2 says to code 8574/3 only when there is no history of previous prostate adenocarcinoma or history of androgen-deprivation therapy.

The WHO Blue Book does confirm this is a treatment-related histology, so it seems we would only use this for an adenocarcinoma with neuroendocrine differentiation (or even possibly a mixed histology tumor with adenocarcinoma and small cell carcinoma components) if the patient had previous treatment.

If this histology is treatment-related, why would we use this code for a patient without a history of prostate adenocarcinoma or androgen-deprivation therapy? Should Note 2 be corrected?

Does this histology apply to a post-treatment diagnosis of mixed adenocarcinoma and small cell carcinoma? If yes, should this clarification be added?

The 2022 ICD-O-3.2 Implementation Guidelines indicate “Tubulovillous adenoma, high grade” is 8263/2 and is not SEER reportable. However, the 2024 SEER Manual and clarification from recent SINQs (20240021 and 20240025) confirm high grade dysplasia in the esophagus, stomach, and small intestine is reportable (8148/2).

Which reportability reference applies to a diagnosis of a tubulovillous adenoma with high grade dysplasia in non-colorectal sites?

The Solid Tumor Rules state that for cases diagnosed in 2022 and forward, p16 testing CAN be used to assign histology code 8085 (squamous cell carcinoma, HPV positive). The rules also state that for cases diagnosed prior to 1/1/2022, code 8085 MUST be based on ISH testing and not p16. ISH testing is not specifically addressed for 2022+ cases, but are we correct in assuming it can still be used as the basis for 8085?

Multiple CAnswer Forum posts and the AJCC 8th edition Head and Neck staging webinar indicate that the correct chapter/registry staging schema in this situation is determined ONLY by p16 results - not ISH testing, and therefore the Schema Discriminator 2 SSDI should be coded as 1 – p16 negative, regardless of ISH results.

While we understand that histology codes should not be changed based on staging criteria, there is a SEER/NAACCR edit, “Schema Discriminator 2, Head and Neck, Histology (NAACCR)” tag number N6802, that will not allow coding 8085 if Schema Discriminator 2 is coded as 1 (p16 negative). The edit does seem to be correctly enforcing the AJCC guidelines for choosing the staging schema, based on the sources noted above. Do the Solid Tumor or Site-Specific Data Items (SSDI) guidelines need to be modified for this situation?

There are multiple possible entries (rows) for a tumor with a neuroendocrine component and non-neuroendocrine component, but these rows do not specify which primary sites are applicable. Row 1 (Combined small cell carcinoma, 8045) seems applicable to a prostate primary, but not to a GI primary since GI primaries are now generally referred to as MiNENs (mixed neuroendocrine non-neuroendocrine tumors), but Table 2 does not provide any instructions regarding how to determine the difference between 8045 and 8154 (or 8244).

For SEER Workshop Case 03 (mixed prostate case), many users selected 8154 or 8244 as the mixed histology code per Table 2, but these histology codes are not listed as applicable in Table 3 (Prostate Histologies). Per the WHO Blue Books, these histologies are not listed as applicable to the prostate.

How are registrars to determine the correct mixed code without site designations, especially if they don't have access to the WHO Blue Book or to a pathologist who may be able to clarify the codes?