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The left thyroid lobectomy/isthmusectomy returned a diagnosis of sclerosing mucoepidermoid carcinoma with eosinophina, 6.5 cm, replacing nearly the entire left lobe of the thyroid.

The patient has a completion thyroidectomy of the right lobe and returned the diagnosis of papillary thyroid carcinoma, 0.5 mm, in maximum dimension.

The endocrinologist describes it as "co-exsisting" and states the tumor is iodine non-avid.

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?

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?

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?

The term “poorly differentiated carcinoma (NOS)” is listed as related to “undifferentiated carcinoma (NOS)” in the ICD-O 3.2. It is also listed in the Solid Tumor Rules for Urinary Table 2 (Urinary subtypes), Other Sites Table 16 (uterine corpus primaries) and Table 19 (vulvar primaries).

Are these the only sites in which one should code “poorly differentiated carcinoma (NOS)” as 8020 (undifferentiated carcinoma)?

How is histology coded if the only microscopic confirmation is from a metastatic site showing “poorly differentiated carcinoma” (NOS) or “invasive carcinoma, poorly differentiated” (NOS)?

Example 1: Primary pancreatic cancer diagnosed on imaging and confirmed with liver mets core biopsy showing “poorly differentiated carcinoma.” Immunostaining pattern was non-specific. No further workup or treatment was planned.

Other Sites - Table 11 (Pancreas Histologies) includes undifferentiated carcinoma (8020/3) as a valid histology; however, the synonyms/subtypes/variants do not mention poorly differentiated carcinoma. How should histology be coded for this case?

Example 2: Hemicolectomy with cecal tumor final diagnosis of “invasive carcinoma, poorly differentiated” and synoptic summary listing “Histologic type: Invasive carcinoma. Histologic grade: G3 of 4: poorly differentiated.”

Colorectal Table 1 (Specific Histologies and Subtypes/Variants) includes undifferentiated adenocarcinoma/carcinoma 8020 as a subtype of adenocarcinoma NOS. There is no mention of poorly differentiated in this context. How should histology be coded for this case?

An argument could be made to apply Rule M10 (timing rule which may result in reporting the case as an additional primary) because the 2022 primary included multiple non-invasive urothelial carcinoma tumors in both the bladder and other urinary sites (coded to site C689, not C679) following a long disease-free interval. While Rule M10 excludes multiple bladder tumors, does that also apply when new, multifocal urothelial tumors arise in both bladder and other urinary sites? Does the presence of any subsequent bladder tumor rule out the use of M10 and one must use M11 that indicates reporting this disease process is a single primary?

10/2017 Bladder cancer diagnosed as invasive papillary urothelial bladder carcinoma (8130/3) (submucosal invasion).

12/2017 Surveillance scope and transurethral resection of bladder tumor (TURBT) finds “recurrent” bladder tumor, non-invasive papillary urothelial bladder carcinoma (8130/2) - same primary per 2007 Multiple Primaries/Histology, Rule M6, (both papillary urothelial bladder carcinomas).

4/2018 Radical nephrectomy found focally invasive urothelial carcinoma (8120/3) in the renal pelvis.

Is this a new primary per 2018 and forward STR, Rule M6, because it was more than 60 days since the 12/2017 in situ bladder recurrence? Or would one compare the 2018 diagnosis to the original invasive bladder tumor in 10/2017, and continue on to Rule M11, which says to abstract a single primary for urothelial carcinomas in multiple organs, regardless of behavior?

SINQ #20120080 said to compare to the original diagnosis and disregard intervening recurrences, but that pertained to the 2007 MP/H rules. Does this still apply for 2018 forward? STR, Rule M10, Note 3, states when there is a recurrence within three years of diagnosis, the “clock” starts over. The time interval is calculated from the date of last recurrence. Comparing each recurrence for urothelial carcinomas using Rule M6 could result in over-counting them. Can the instructions on how to calculate the 60-day interval be clarified in Rule M6?

The patient underwent a gross total resection of the 2005 glioblastoma multiforme (9440/3). The patient was subsequently diagnosed with a 2024 diagnosis of astrocytoma, IDH-mutant, WHO grade 4 (9445/3).

Should Rule M13 apply to the new 2024 diagnosis and a new primary be accessioned because astrocytoma, IDH-mutant, WHO grade 4 is listed on a different row than glioblastoma? It is unclear whether histology 9445 should be classified as being on a different row because it is also listed as a subtype/variant for glioblastoma in Table 3. Table 3 lists histology 9445 as both “Astrocytoma, IDH-mutant, WHO grade 4” and as “Glioblastoma IDH-mutant.”

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.