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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.

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? 

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.

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.”

The WHO Classification of Hematopoietic Tumors (Blue Book), 5th edition states: “Rare cases of classic follicular lymphoma with cytological features of follicular lymphoma (FL) grade 3A can present with a prominent diffuse pattern. In the previous edition, such cases were defined as diffuse large B-cell lymphoma (DLBCL). Currently, it is uncertain whether such cases should be classified as FL or diffuse large B-cell lymphoma; and in such cases, individual treatment choices should be made in multidisciplinary conference settings taking into consideration clinical, laboratory, and imaging parameters. The presence of diffuse areas composed entirely or predominantly of large cells, however, warrants a diagnosis of diffuse large B-cell lymphoma.”

Our concern is that the Hematopoietic (Heme) Manual and Database do not provide instruction for coding this scenario. We hesitate to interpret the terms “equivalent to” as ambiguous because one could argue it is unambiguous. Barring this argument, the M and H rules would indicate this is a diagnosis of diffuse large B-cell lymphoma. However, the physician does not seem to agree with the pathologist.

Malignant Central Nervous System (CNS) Rule M5 instructs us to abstract a single primary (as malignant) when a single tumor is originally diagnosed as non-malignant, the “First course treatment was active surveillance (no tumor resection),” and the subsequent resection pathology is malignant.

This patient’s first course of treatment was not active surveillance. While the patient did not have first course tumor resection, the tumor was treated with Cabergoline.

Should Rule M5 apply because there was no tumor resection? If so, should Rule M5 clearly state no tumor resection is the criteria (not active surveillance)?

SINQ 20230023 does indicate a PitNET diagnosis following a diagnosis of pituitary adenoma does not fall into standard rules, but in the previous SINQ the first course treatment was a partial resection.

It is unclear whether other types of treatment could result in a new malignant PitNET, following a previously treated non-malignant pituitary tumor.