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Patient had a total abdominal hysterectomy-bilateral salpingo-oophorectomy performed in January 2023 with final diagnosis of myxoid and epithelioid leiomyosarcoma.

Diagnosis comment states: The tumor is 15 cm per report. It grows in nests and poorly formed interanastomosing trabeculae and cords that are separated by abundant myxoid background. The cells have an epithelioid morphology with eosinophilic cytoplasm, large nuclei, and very prominent nucleoli. The mitotic activity is overall low ranging from 1 to 3/10 HPFs.

Immunohistochemical stains performed at the outside hospital showed diffuse positivity for SMA, desmin, caldesmon, and PR. They are negative for CD10, claudin-4, calretinin, HBM45, MART1 (rare weakly positive cells), PANCK, and SOX10. This immunohistochemical profile supports a smooth muscle derivation of this neoplasm. As this tumor is extensively myxoid, diagnostic criteria differ from the spindle cell leiomyosarcoma.

Per Solid Tumor Rules Other Sites, Table 16: Uterine Corpus Histologies, Epithelioid Leiomyosarcoma (8891/3) and Myxoid Leiomyosarcoma (8896/3) are both subtypes of Sarcoma, NOS (8800/3).  Per Rule H21, use a combination code when there are multiple specific histologies AND the combination is listed in Table 2 OR there are coding instructions for the combination in the applicable histology Tables 3-21 OR you receive a combination code from Ask A SEER Registrar.  Since there is no combination listed in Table 2 and there is no instruction for the combination in Table 16, how should the histology be coded for this tumor?

In the 2024 Solid Tumor Rules update, the small cell neuroendocrine carcinoma row in Table 2 was changed. The NOS histology became neuroendocrine carcinoma, NOS (8246) and both large cell and small cell neuroendocrine carcinomas (8013 and 8041, respectively) became the subtype/variants. This change impacts Rule H4 but Rule H4 was not updated. Rule H4 still refers to small cell neuroendocrine carcinoma as being the NOS histology.

In the prior STR versions, it was clear the tumor in question would be coded as 8045 per Rule H4 and Table 2. Considering Rule H4 was not updated according to the changes for Table 2, does histology 8045 still apply to this diagnosis?

There is currently no way to arrive at a histology for this case. Does Rule H4, bullet 3 need to be updated to indicate, “subtype/variant of neuroendocrine carcinoma mixed with any other carcinoma (does not apply to sarcoma)”?

Should Note 2 state, "Beginning with cases diagnosed 1/1/2023 forward, diffuse leptomeningeal glioneuronal tumor is coded 9509/3? See the Malignant CNS rules." Currently the Note only states, "leptomeningeal glioneuronal tumor," but the histology that changed behavior is listed in both Table 6, Column 1 (Non-Malignant CNS) and Table 3 (Malignant CNS) as, "Diffuse leptomeningeal glioneuronal tumor."

The only Other Sites H Rule related to extramammary Paget disease is included in the Multiple Tumors Abstracted as a Single Primary module. Rule H28 instructs one to code the histology of the underlying tumor when there is extramammary Paget disease and an underlying tumor of the anus, perianal region, or vulva. Therefore, a vulvar extramammary Paget disease with underlying adenocarcinoma is coded as adenocarcinoma (8140/3), and not extramammary Paget disease (8542/3).

However, there is no M Rule confirming extramammary Paget disease and the underlying adenocarcinoma are a single primary (i.e., multiple tumors abstracted as a single primary) making it difficult for one to use the Multiple Tumors Abstracted as a Single Primary H rules module.

We recognize this is a longstanding histology coding rule, but how are registrars supposed to arrive at Rule H28 when the M Rules must be applied first and do not instruct one to accession a single primary? Moreover, if this is to be a single primary (per rule M2), why is there no H Rule in the Single Tumor module?

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?

Patient was diagnosed on imaging with enhancement along the right optic nerve intraorbital segment, displacing the optic nerve, most consistent with optic nerve sheath meningioma.

Extracranial meningiomas are rare, however SINQ 20230052 does contain an exception for reportability in a different head and neck site because it is not an intracranial location.

It is unclear if this portion of the meninges surrounding the intraorbital optic nerve is still “intracranial” and thus reportable.