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This patient does not have a previous diagnosis of prostate adenocarcinoma nor a previous history of androgen-deprivation therapy.

Does the logic in the Other Sites Solid Tumor Rules (STRs) noted in SINQ 20200052 still apply? This SINQ confirms a diagnosis of mixed prostatic adenocarcinoma and small cell neuroendocrine carcinoma is 8045. This matches the STRs instructions for Rule H21 and Table 2 (Mixed and Combination Codes), row 1. Row 1 indicates a mixed small cell carcinoma and adenocarcinoma is combined small cell carcinoma (8045). For a patient without previous treatment, is this the correct mixed histology code?

Note 1 states that this histology is treatment-related neuroendocrine prostatic carcinoma demonstrating complete neuroendocrine differentiation or partial neuroendocrine differentiation with adenocarcinoma after androgen-deprivation therapy (ADT). Conversely, Note 2 says to code 8574/3 only when there is no history of previous prostate adenocarcinoma or history of androgen-deprivation therapy.

The WHO Blue Book does confirm this is a treatment-related histology, so it seems we would only use this for an adenocarcinoma with neuroendocrine differentiation (or even possibly a mixed histology tumor with adenocarcinoma and small cell carcinoma components) if the patient had previous treatment.

If this histology is treatment-related, why would we use this code for a patient without a history of prostate adenocarcinoma or androgen-deprivation therapy? Should Note 2 be corrected?

Does this histology apply to a post-treatment diagnosis of mixed adenocarcinoma and small cell carcinoma? If yes, should this clarification be added?

We included this histology in SEER Workshop Case 12 and the histology coding accuracy was less than 40%. From emails we received, it is clear that registrars are unaware that the "somatic type malignancy" can vary but code 9084 applies when the diagnosis is teratoma WITH any non-germ cell tumor component. It may be helpful to add a definition for "teratoma with somatic-type malignancy" (9084) to the Solid Tumor Manual.

Patient had a hemithyroidectomy with the final diagnosis above. There does not appear to be an Other Sites H rule or table that addresses this combination of histologies for thyroid primaries.

There is an ICD-O histology code for papillary carcinoma, columnar cell (8344/3) as well as papillary carcinoma, encapsulated (8343/3). Per Rule H13, the terms “with features of” may be used to identify a subtype.

Considering these two subtypes, and knowing there is no specific histology code for this combination, is the first rule that applies H17 (code the numerically higher histology code)?

2016 Total thyroidectomy, Multifocal

-Dominant Tumor:  Right Lobe, Papillary thyroid carcinoma (8260/3)

-Tumors two through five:  Three tumors Papillary thyroid carcinoma (8260/3), and one tumor Papillary thyroid carcinoma, follicular variant (8340/3)

-An additional tumor: Non-invasive follicular thyroid neoplasm with papillary-like nuclear features (8343/2)

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 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?