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The WHO Blue Books do not include dedifferentiated carcinoma as a valid histology for the breast.  However, there is known to be progression of ductal carcinoma that is essentially dedifferentiation of an estrogen receptor, progesterone receptor, and HER2 breast carcinoma to a triple negative "dedifferentiated" carcinoma which it appears this patient has. Whether we should accession this as a separate 8020/3 primary per M14 is unclear and the Solid Tumor Manual does not address this scenario.

The UroVysion website says that standard procedures, e.g., cytology, cystoscopy, take precedence over the UroVysion test. The Quest Diagnostics website says that "A positive result is consistent with a diagnosis of bladder cancer or bladder cancer recurrence, either in the bladder or in another site within the urinary system. A negative result is suggestive of the absence of bladder cancer but does not rule it out." Would we pick up the case if the UroVysion test was positive but the standard procedures were negative or non-diagnostic?

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.

The Summary Cancer Data does not seem to describe a more specific histology, but it does describe the tumor histology with the worst outcome and the most extensive tumor. The anaplastic carcinoma grossly extended into skeletal muscle and gave rise to multiple regional lymph node metastases. The more appropriate histology seems to be 8021.

However, current MP/H Rules for a single tumor indicate the histology should be coded to the numerically higher histology code (8260). Coding the histology to 8260 does not account for the more aggressive tumor. Should this histology be 8260 or 8021?

The Solid Tumor histology coding guideline #3 for Lung states that an ambiguous histology can only be coded over an NOS when a physician clinically confirms it or the patient receives treatment based on the ambiguous histology; similar instructions exist in rules H3 and H12.  We are in a central registry and don't typically have access to physician notes or treatment plans; unfortunately our hospital abstracts rarely document physician confirmation of ambiguous histology and we are uncertain if we should accept their coding of the more specific histology, assuming they did find clinical confirmation that was not documented.  If not, our understanding of the Solid Tumor rules is that the histology in such a case would have to be coded as malignancy NOS (8000/3) per the non-ambiguous final diagnosis, and that we cannot use the more specific but ambiguous squamous cell carcinoma since we don't have definite clinical confirmation.  We also have a fair number of cytology-only lung cases without any hospital information to clinically confirm an ambiguous histology.

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?

The Solid Tumor Rules instruct us not to use differentiation for coding histology unless it is specifically listed in the table. The terminology non-small cell carcinoma with neuroendocrine differentiation is not in lung histology Table 2.

However, SINQ 20150033, prior to Solid Tumor rules, indicates this diagnosis should be coded to 8574 (adenocarcinoma/carcinoma with neuroendocrine differentiation).

This presentation appears to represent distinctly different histologies. However, because the 2018 histology diagnosis is not in the table and the prior SINQ appears to disagree with current instruction, it is not clear how to apply the M rules to this case. The outcome of the histology coding will affect the number of primaries reported in this case.

The Solid Tumor Rules indicate p16 is a valid test to determine HPV status and can be used to code HPV-associated/-independent.

In this case, we do not know whether the HR-HPV test was done on cytologically malignant cells, or on benign cervical cells. It may be impossible to tell unless 100% of the cytology specimen is malignant, but we will not have access to that information. Also, HR-HPV testing is routine on Pap smears, so this testing does not mean the tumor cells specifically harbor HPV.

The Solid Tumor Rules indicate bladder tumors that are urothelial carcinoma (8120) and small cell carcinoma (8041) are separate primaries per Rule M13 (Abstract multiple primaries when separate/non-contiguous tumors are on different rows in Table 2). These are distinctly different histologies and, presumably, one would want to capture the small cell carcinoma (or small cell carcinoma component) as this has a worse prognosis.

However, if a subsequent bladder tumor is composed of invasive urothelial carcinoma and small cell neuroendocrine carcinoma, the histology is coded as 8045/3 per Rule H4, but this is not abstracted as a multiple primary. The only M Rule that applies is Rule M18 (Abstract a single primary when tumors do not meet any of the above criteria). The mixed histology code 8045 is not included in Table 2, so none of the histology-based M Rules apply. Is the subsequent mixed invasive urothelial and small cell carcinoma tumor (8045/3) the same primary as a previously diagnosed invasive urothelial carcinoma (8120/3) when these tumors are diagnosed within three years?

The Single Versus Subsequent Primaries of Lymphatic and Hematopoietic Diseases table indicates they are most likely "D" different disease processes. As any low grade lymphoma can transform, we suspect this represents a transformation (the clinician is regarding this as transformed).

How many primary/ies should be coded?

And, how?