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Historically, multiple invasive ductal and lobular carcinomas diagnosed within 5 years were abstracted as a single primary. However, it is not clear if Rule M10 or M14 applies to this situation per the 2023 Solid Tumor Rules updates.

Rule M10 addresses multiple tumors of carcinoma of no special type (NST)/duct and lobular, but there is no timing criteria mentioned. Does M10 apply to cases diagnosed synchronously, or metachronously, or at least within 5 years? Should Rule M10 include a Note instructing registrars to accession a single primary for the scenario in question?

If timing matters for Rule M10, then the next rule that applies is M14. Rule M14 instructs one to abstract multiple primaries when separate/non-contiguous tumors are on different rows in Table 3, and carcinoma NST/duct and lobular carcinoma are on separate rows in Table 3.

SINQs 20190083, 20180088, and 20130221 all indicate diagnoses of prostate adenocarcinoma, followed by a diagnosis of metastatic small cell carcinoma of the prostate are separate primaries because these are distinctly different histologies. Does this logic still apply for 2023 and later since Rule M4 was added to the Other Sites M Rules? Rule M4 states, “Abstract multiple primaries when the patient has a subsequent small cell carcinoma of the prostate more than 1 year following a diagnosis of acinar adenocarcinoma and/or subtype/variant of acinar adenocarcinoma of prostate.”

This patient has a 2018 diagnosis of prostate adenocarcinoma treated with radical prostatectomy, followed by a 2023 diagnosis of metastatic small cell carcinoma of the prostate diagnosed on a liver metastasis core biopsy. Rule M4 does not indicate whether it applies to subsequent biopsy confirmed metastatic tumor only. When a diagnosis of small cell carcinoma follows a diagnosis of prostatic adenocarcinoma, it is almost always confirmed in metastatic sites rather than in the primary site. Does the logic in the referenced SINQs above still apply for Rule M4?

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?

These diagnoses were made greater than one year apart with a disease-free interval and M12 seems to be the first rule that applies. This rule does not specifically state the tumors diagnosed greater than 1 year apart must be in the same primary site but Note 1 could be interpreted as implying this. Note 1 states, “Clinically disease-free means that there was no evidence of recurrence in the same site on follow-up.”

Does Other Sites Rule M12 (the timing rule) apply to tumors in different primary sites? It would be helpful if the notes specified this clarification, such as “Clinically disease-free means that there was no evidence of recurrence in the same site (same second and third character CXX.X) on follow-up.”

Now that there are specific surgery codes for shave and punch biopsies, are these biopsies always the Date of First Surgical Procedure (NAACCR Item #1200)? Or should we still be applying the Surgery of Primary Site 2023 instruction in the SEER Manual that states shave or punch biopsies are most often diagnostic; code as a surgical procedure only when the entire tumor is removed and margins are free/gross disease is removed?

We are aware of the instruction for melanoma cases outlined in SINQ 20230034; however, it is unclear if this should also apply to cutaneous lymphomas and Kaposi sarcomas, or if the intent of the procedure is used for these specific types of skin cases that typically present with multifocal involvement.

Example 1: Patient is diagnosed March 2023 with primary cutaneous T-cell lymphoma presenting as pink, tan patches on the trunk. Punch biopsy diagnosed CTCL and treatment was given via narrow band UVB phototherapy.

Example 2: Patient is diagnosed February 2023 with Kaposi sarcoma presenting as widespread violaceous macules, papules, plaques on the torso, bilateral extremities, and abdomen. Punch biopsy diagnosed Kaposi sarcoma.

In 2021, the patient was diagnosed with a non-reportable appendiceal LAMN.  Resection showed a tumor diffusely involving the appendix and perforating the visceral peritoneum, as well as extensive intraperitoneal metastasis.  In 2023, a lung wedge resection revealed metastatic mucinous neoplasm involving lung parenchyma and pleura, consistent with metastasis of the known appendiceal primary.  It is understood that intraperitoneal spread of an appendiceal LAMN does not make it reportable because the peritoneal disease is also non-invasive.  Does extraperitoneal metastasis of an appendiceal LAMN diagnosed prior to 2022 make it invasive disease and therefore reportable? 

The WHO Blue Books do not include dedifferentiated carcinoma as a valid histology for the breast.  However, there is known to be progression of ductal carcinoma that is essentially dedifferentiation of an estrogen receptor, progesterone receptor, and HER2 breast carcinoma to a triple negative "dedifferentiated" carcinoma which it appears this patient has. Whether we should accession this as a separate 8020/3 primary per M14 is unclear and the Solid Tumor Manual does not address this scenario.

Disease History

2018 - Lymphomatoid papulosis (non-reportable)

2020 - Transform to CTCL (and called Mycosis Fungoides specifically) (CTCL/MF same primary)

2021 - Transform to CTCL with large cell transformation

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?

The patient had residual tumor following the 2018 transsphenoidal resection and underwent an additional surgery after the residual tumor increased in size. Since pituitary adenoma/pituitary neuroendocrine tumor (PitNET) is a new malignant neoplasm for cases diagnosed 2023 and later, should this be a new primary per M5? Or do we disregard the change in behavior and apply rule M2 (single tumor is a single primary) for this scenario?