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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?

In the 2024 Solid Tumor Rules update, the small cell neuroendocrine carcinoma row in Table 2 was changed. The NOS histology became neuroendocrine carcinoma, NOS (8246) and both large cell and small cell neuroendocrine carcinomas (8013 and 8041, respectively) became the subtype/variants. This change impacts Rule H4 but Rule H4 was not updated. Rule H4 still refers to small cell neuroendocrine carcinoma as being the NOS histology.

In the prior STR versions, it was clear the tumor in question would be coded as 8045 per Rule H4 and Table 2. Considering Rule H4 was not updated according to the changes for Table 2, does histology 8045 still apply to this diagnosis?

There is currently no way to arrive at a histology for this case. Does Rule H4, bullet 3 need to be updated to indicate, “subtype/variant of neuroendocrine carcinoma mixed with any other carcinoma (does not apply to sarcoma)”?

Example: 12/2023 Breast lumpectomy final diagnosis is Invasive ductal carcinoma, lymphoepithelioma-like carcinoma type. This is a single tumor with no in situ carcinoma present.

Lymphoepithelioma-like carcinoma is not listed as a subtype/variant or synonym for breast carcinoma in the Solid Tumor Rules histology tables.

There appears to be discrepant information in the 2024 (and prior) SEER manual regarding race coding when the patient is described only as Hispanic/Latina. Page 78 tells us to Code as 01 (White) when: b. There is a statement that the patient is Hispanic or Latino(a) and no further information is available

1. A person of Spanish origin may be any race; however, for coding race when there is no further information other than “Hispanic” or “Latino(a),” assign race as White as a last resort instead of coding unknown.

However, in Appendix D, under "Other Race descriptions", there is a statement that "If no further information is available, code as 99 Unknown." The list includes "Hispanic."

Based on the Solid Tumor Rules, we would make this two since it is over one year. According to a previous SINQ question 20110046, we are to code this as one primary. We see patients come back with multiple carcinoid tumors over the years and would like clarification.

There are multiple possible entries (rows) for a tumor with a neuroendocrine component and non-neuroendocrine component, but these rows do not specify which primary sites are applicable. Row 1 (Combined small cell carcinoma, 8045) seems applicable to a prostate primary, but not to a GI primary since GI primaries are now generally referred to as MiNENs (mixed neuroendocrine non-neuroendocrine tumors), but Table 2 does not provide any instructions regarding how to determine the difference between 8045 and 8154 (or 8244).

For SEER Workshop Case 03 (mixed prostate case), many users selected 8154 or 8244 as the mixed histology code per Table 2, but these histology codes are not listed as applicable in Table 3 (Prostate Histologies). Per the WHO Blue Books, these histologies are not listed as applicable to the prostate.

How are registrars to determine the correct mixed code without site designations, especially if they don't have access to the WHO Blue Book or to a pathologist who may be able to clarify the codes?

The CT findings identified a right kidney rim-enhancing centrally cystic lesion most suggestive of clear cell renal cell carcinoma measuring 3.2 cm.  The radiologist’s impression was “concerning for renal cell carcinoma.” The subsequent urologist’s consult states the right kidney lesion has a 75% chance of malignancy. The urologist discussed active surveillance, surgery, and ablation, and after discussion with the patient the plan was for active surveillance.

No further information is available, and we are unable to follow up with the physician regarding this case.

Should a lesion with a high percentage chance of malignancy (e.g., 75% chance) be considered a lesion “most likely” to be malignant?

Per Solid Tumor Manual Other Sites Rule M6, despite the number of areas of involvement, any presentation of Kaposi sarcoma is always a single primary. The primary site is skin using the Kaposi Sarcoma for All Sites Coding Guidelines (Appendix C, 2023 SEER Manual). 

Does SEER Program Coding and Staging Manual Laterality Coding Instruction #4 preclude the use of code 4 [Bilateral involvement at time of diagnosis...] if a patient presents with KS involvement of only both arms or only both sides of the face?