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In the September 2021 Urinary Sites Solid Tumor Rules update, the term configuration was removed from the “DO NOT CODE histology when described as” list. However, it was not added as a term that can be used to code the more specific histology for urinary tumors.

Can configuration be used to code the more specific histology 8130 (papillary urothelial carcinoma) when the diagnosis is urothelial carcinoma, tumor configuration: papillary?

Example: Patient has a left cerebral meningioma that is meningothelial meningioma (9531) and two right-sided cerebral meningiomas: one that is transitional meningioma (9537) and the other that is meningioma, transitional and angiomatous, WHO Grade I. If the histology for the mixed tumor is 9534 (angiomatous meningioma), then there are three primaries. If the histology is 9537 (transitional meningioma), then there are two primaries.

Per Table 6, angiomatous meningioma is 9534/0 and transitional meningioma is 9537/0. There is no mixed histology coding rule, or mixed histology meningioma code. There is also no default rule that would instruct registrars to code the numerically higher ICD-O code or to default to a meningioma (NOS) histology code.

A recent molecular study of PNET tumors at NCI (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5139621) seems to indicate the discovery of four new CNS tumor entities, of which HGNET-BCOR is one. The article suggests that these are not primitive neuroectodermal tumors tumors (PNET), but something different.

The patient has testicular cancer with bilateral lung metastases and possible liver metastasis. The left orchiectomy final diagnosis was The Summary describes a single tumor that is, Germ cell neoplasia in situ (GCNIS) is also present. Although there is mixed germ cell tumor present, the PNET component of the tumor is locally invasive extending into the epididymis, hilar soft tissues, spermatic cord, and tunica vaginalis. The mixed germ cell tumor is limited to the testis only.

We are instructed not to use to the term to code histology in the MP/H Rules General Instructions (Other Site Rules not updated for 2018), however the PNET comprises the majority of this tumor and represents the most extensive disease. Should the PNET histology be ignored in this case as its a ?

Rule M15

Abstract a single primary when synchronous, separate/non-contiguous tumors are on the same row in Table 2 in the Equivalent Terms and Definitions.

Note: The same row means the tumors are

• The same histology (same four-digit ICD-O code) OR

• One is the preferred term (column 1) and the other is a synonym for the preferred term (column 2) OR

• A NOS (column 1/column 2) and the other is a subtype/variant of that NOS (column 3) OR

• A NOS histology in column 3 with an indented subtype/variant

Example: TURBT shows invasive papillary urothelial carcinoma 8130/3 and CIS/in situ urothelial carcinoma 8120/2. Abstract a single primary. Papillary urothelial carcinoma and urothelial carcinoma are on the same row in Table 3.

In previous STR versions and the ICD-O-3.2, SFT/hemangiopericytoma, WHO G1 is 8815/0 and only SFT/hemangiopericytoma, WHO G2 was 8815/1. However, Table 6 (Non-Malignant CNS, Specific Histologies, NOS, and Subtypes/Variants) was changed in the 2025 updates to indicate both G1 and G2 SFT/hemangiopericytoma are 8815/1.

No date range was provided for this change in the STR and the behavior of this tumor was not updated by the standard setters in other references (i.e., ICD-O-3.2). The behavior of G1 SFT/hemangiopericytoma was not updated in the 2025 ICD-O-3.2 updates. If the ICD-O-3.2 was the source of this change, should this have been documented in the 2025 NAACCR Implementation Guidelines? However, the 2025 NAACCR Implementation Guidelines indicates, "There are no ICD-O-3 changes for 2025." Is this behavior change in 2025 Solid Tumor Rules updates an error? Should the behavior of SFT/hemangiopericytoma, WHO G1 remain /0? 

It appears there was some confusion about finding this new malignant HGAP tumor (2023+) code. If this is not a specific subtype/variant of astrocytoma, can clarification be added to the “New for 2023” entry for HGAP?

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."

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).