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We are seeing cases on this in head and neck. The College of American Pathologists Oral Cancer Protocol is showing this as keratinizing dysplasia, severe (carcinoma in situ) and nonkeratinizing dysplasia, severe (carcinoma in situ). SINQ Question 20230047 shows it as reportable for head and neck.

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? 

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)

Patient had a left thigh soft tissue mass excision on 7/24/24 and was diagnosed with superficial CD34 positive fibroblastic tumor. Margins were narrowly free of disease. Tumor size was 5.5 cm x 4.4 cm x 3.9 cm. The diagnosis was confirmed.

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.