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March 2022, left shoulder soft tissue mass excision shows a spindle cell tumor with outside consultation diagnosis of malignant neoplasm with neuroectodermal differentiation and TPR-NTRK1 gene rearrangement. Diagnosis comments indicate the findings most closely resemble the spectrum of kinase-rearranged mesenchymal neoplasms, such as lipofibromatosis-like neural tumor. However, the expression of SOX10 and mature melanocytic markers is unusual, and does not exclude melanocytic differentiation.

Should this be classified as a peripheral neuroectodermal tumor (9364) or as an "NTRK-rearranged spindle cell neoplasm (emerging)" (8990) if there is a NTRK gene rearrangement?

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?

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.

Appendix E1 in both the 2023 and 2024 SEER Program Coding and Staging Manual (SPCSM) lists these malignant spindle cell neoplasms, consistent with atypical fibroxanthoma, as reportable when other tumors have been ruled out with immunohistochemistry. This contradicts both SINQ 20190102 and the Solid Tumor Rules (STRs) general instructions indicating ambiguous terminology (e.g., “consistent with”) cannot be used to code the more specific histology when there is a NOS (malignant spindle cell neoplasm, 8004/3) and a more specific (malignant atypical fibroxanthoma, 8830/3) histology.

These tumors are typically diagnosed and treated in dermatology offices, so further chart review or confirmation by a physician is not possible for central registries.

As non-melanoma skin primaries are included in the Other Sites schema, and this schema was updated for cases diagnosed 2023 and later, which instruction applies to 2023+ diagnoses? Should these continue to be collected per Appendix E1 despite the conflict with the STR Manual and SINQ? If these are reportable, should the SINQ and STR Manual be updated to reflect this? Or should these be non-reportable per the STR Manual and SINQ?

The Solid Tumor Rules state that for cases diagnosed in 2022 and forward, p16 testing CAN be used to assign histology code 8085 (squamous cell carcinoma, HPV positive). The rules also state that for cases diagnosed prior to 1/1/2022, code 8085 MUST be based on ISH testing and not p16. ISH testing is not specifically addressed for 2022+ cases, but are we correct in assuming it can still be used as the basis for 8085?

Multiple CAnswer Forum posts and the AJCC 8th edition Head and Neck staging webinar indicate that the correct chapter/registry staging schema in this situation is determined ONLY by p16 results - not ISH testing, and therefore the Schema Discriminator 2 SSDI should be coded as 1 – p16 negative, regardless of ISH results.

While we understand that histology codes should not be changed based on staging criteria, there is a SEER/NAACCR edit, “Schema Discriminator 2, Head and Neck, Histology (NAACCR)” tag number N6802, that will not allow coding 8085 if Schema Discriminator 2 is coded as 1 (p16 negative). The edit does seem to be correctly enforcing the AJCC guidelines for choosing the staging schema, based on the sources noted above. Do the Solid Tumor or Site-Specific Data Items (SSDI) guidelines need to be modified for this situation?

Additional comments in this pathology report state "The entire case was sent in consultation to an ophthalmic pathologist. [Pathologist] assigns a conjunctival melanocytic intraepithelial neoplasia (C-MIN) score of 2-3 due to the upward pagetoid migration of small, dendritic melanocytes. A C-MIN score of 2-3 is between low-grade conjunctival melanocytic intraepithelial lesion (LG-CMIL; C-MIN 2) and high-grade conjunctival intraepithelial lesion (HG-CMIL; C-MIN 3). The older terminology for this lesion would be primary acquired melanosis (PAM) with mild to focally moderate atypia."

This term does not appear in the SEER Program Coding and Staging Manual (SPCSM), Appendix E1 of the SPCSM, or Solid Tumor Rules (specifically rule H3) .