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The STR states that p16 can be used to code HPV-associated and HPV-independent histologies for selected sites depending on diagnosis year but contains no instructions about how to interpret p16 staining results on pathology reports. These are often stated in various ways in our area, depending on the pathology lab and different pathologists. The SSDI Manual and SEER Coding and Staging Manual each have some instructions and code definitions for p16, including:

- Code 0 for p16 expression of weak intensity or limited distribution

- Code 0: p16 Negative; Nonreactive

- Code 1: p16 Positive; Diffuse, Strong reactivity

- IHC for p16 expression is a surrogate marker for HPV infection

Example: 2023 squamous cell carcinoma of the vulva, partial vulvectomy; pathology states vulvar intraepithelial neoplasia-3, p16 immunohistochemistry demonstrates block-like expression, which supports the diagnosis. The next path report states invasive squamous cell carcinoma, stain for p16 is strong and diffuse in the lesion, supporting the above diagnosis. Neither path report specifically states "HPV-related," so are p16 "expression" and "strong and diffuse" staining enough to code the histology as 8085/3 for this case?

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? 

We are increasingly seeing pathologists use this terminology to describe WHO G2 meningiomas, but the histology term "Atypical meningioma" is not being used, and a more specific "Histological Classification" of other WHO Grade 2 meningiomas (i.e., chordoid or clear cell meningioma) is not given. Can the combination of meningioma, WHO Grade 2 plus the histological classification listing multiple features of an atypical meningioma be used to code morphology to 9539/1? Or is this just a meningioma, NOS 9530/0 despite the WHO Grade 2 classification?

CAP Protocol for the Examination of Cystectomy Specimens From Patients With Carcinoma of the Urinary Bladder/Treatment Effect Post Neoadjuvant Chemotherapy (BCG not included) selections

o No known presurgical neoadjuvant therapy

o Complete response: Absence of histologically identifiable residual cancer cells and extensive fibrosis of the tumor bed after presurgical neoadjuvant therapy (TRG1)

o Strong response: Predominant fibrosis of the tumor bed, with residual cancer cells occupying less than 50% of this area (TRG2)

o Weak or no response: Residual cancer cells occupying ≥50% of the tumor bed or absence of regressive changes (TRG3)

o Other (specify): _________________

SEER Coding Instruction for Site-Specific Codes for Neoadjuvant Therapy Treatment Effect - Schemas: All Other Schemas selections

0 Neoadjuvant therapy not given/no known presurgical therapy

1 Complete pathological response

Present: No viable cancer cells/no residual invasive carcinoma identified

Residual in situ carcinoma only

2 Near complete pathological response

Present: Single cells or rare small groups of invasive cancer cells

3 Partial or minimal pathological response

Present: Residual invasive cancer with evident tumor regression, but more than single cells or rare small groups of cancer cells

4 Poor or no pathological response

Absent: Extensive residual cancer with no evident tumor regression

6 Neoadjuvant therapy completed and surgical resection performed, response not documented or unknown

Cannot be determined

7 Neoadjuvant therapy completed and planned surgical resection not performed

9 Unknown if neoadjuvant therapy performed

Unknown if planned surgical procedure performed after completion of neoadjuvant therapy

Death Certificate only (DCO)

In the SEER Program Coding and Staging Manual 2023, under clinical tumor size (page 115, item #12), it states: “For breast tumors, clinical size may be recorded based on the size of a non-mass enhancement (NME). NME is defined as an enhancing abnormality that is not associated with the three-dimensional volume of a mass, shape, and outlining, and it is separate from Background Parenchymal Enhancement (BPE).” This guidance does not appear to have been carried forward into the Tumor Size Summary coding instructions.

In 01/2023, right lower lobectomy final diagnosis proved a single adenocarcinoma tumor with the histological patterns described as acinar (20%), papillary (30%) and solid; complex glands (cribriform and fused glands) (50%). There is no H Rule applicable to a complex glandular pattern adenocarcinoma. Is this equivalent to a solid predominant adenocarcinoma (8230) per Rule H7? Or is the predominant adenocarcinoma a mixed subtype coded as 8255 per Rule H9?

One of the largest hospital systems in our area includes "INDIGENOUS-LATINO/A OR INDIGENOUS-LATINX" and "FIRST NATIONS" as dropdown items for patients to self-select for race/ethnicity. This hospital system serves 51 hospitals and 1,000 clinics across Alaska, California, Montana, New Mexico, Oregon, Texas, and Washington. If "INDIGENOUS-LATINO/A OR INDIGENOUS-LATINX" is the only item selected with no additional text info available, how should Race 1 and Spanish Surname or Origin be coded? If "FIRST NATIONS" is the only item selected without additional text info available, should Race 1 be coded as 03?

There was a single right fallopian tube tumor with two distinct morphologies. The diagnosis comment states, “The combined morphologic and immunohistochemical features are best classified as primary fallopian tube high grade serous carcinoma with a somatically derived yolk sac tumor.”