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Patient failed treatment with Azacitidine for MDS with multilineage dysplasia (9985/3) diagnosed 1/2024, and on re-biopsy of bone marrow 11/2025, histology is now MDS with excess blasts (9989/3). These diagnoses are the same primary using the Hematopoietic and Lymphoid Neoplasms (Heme) Database. The physician has prescribed treatment of Anti-Thymocyte Globulin (ATG)/Cyclosporine/Prednisone. SEER*Rx Database says not to code as ATG and Cyclosporine are antirejection medications post-transplant, but the oncologist is using this combination for treatment.

Historically, synchronous ductal and lobular tumors have been accessioned as a single primary. These were previously covered under Rule M10, which was removed from the (STR) Manual 2026 Update. While the previous iteration of Rule M10 was problematic, the main issue related to the lack of a timing component within the rule (i.e., indicating it applied to synchronous ductal and lobular tumors).

Using the current Breast STR, when there are two (or more) simultaneous tumors which are not mixed lobular and ductal within each tumor, the applicable M Rule is Rule M13: Abstract multiple primaries when separate/non-contiguous tumors are on different rows in Table 3. To apply the M Rules, a provisional histology must be assigned to EACH tumor so we cannot code each tumor as 8522 before we start applying the M Rules. These provisional histologies would be 8500 and 8520, and these are on different rows in Table 3.

The patient has a known history of polycythemia vera (PV). The Hematopoietic and Lymphoid Neoplasms Database (Heme DB) entry for myelodysplasia-related acute myeloid leukemia ("acute myeloid leukemia post myelodysplastic-myeloproliferative neoplasm") states, "The pathologist must make the diagnosis of being myelodysplasia-related." However, it's unclear if the pathologist's statement of an acute myeloid leukemia (AML) "transforming from" counts as the AML being myelodysplasia-related since AML can arise/transform from PV. The Heme DB does indicate histology 9895 should not automatically be used just because the patient has a history of MPN.

The bone marrow did not identify any of the specific cytogenetic or molecular abnormalities listed in the Heme DB. However, next generation sequencing identified mutations in BCOR, DNMT3A, IDH1, JAK2, EZH2. The managing physician's clinical diagnosis was "AML arising from polycythemia vera."

STR Manual, Table 12, Thyroid Histologies, includes "Invasive encapsulated follicular variant of papillary thyroid carcinoma" as histology 8340/3 and is on its own row from other papillary thyroid carcinomas (PTC). A new footnote was added which states, "IEFVPTC and Infiltrative follicular variant of papillary thyroid carcinoma (a PTC subtype) share a histology code, but they are distinctly different histologies. They are on different rows of the table and are different primaries." However, IEFVPTC (and its synonyms) are listed in the ICD-O-3.2 as 8343/3, and 8343/3 was listed as a subtype/variant of papillary thyroid carcinoma in previous versions of the STR Manual.

The patient has an overlapping sinonasal tumor and only underwent diagnostic biopsies of the ethmoid sinus component. Neither biopsy can be determined to be the more representative specimen. The initial biopsy, addendum diagnosis, states there are features in between olfactory neuroblastoma and large cell neuroendocrine carcinoma. The addendum comment states the findings, "makes the distinction between olfactory neuroblastoma (ONB) and neuroendocrine carcinoma difficult."

The final diagnosis on the repeat biopsy (approx. 2 weeks later) was high grade neuroendocrine carcinoma, but the diagnosis comment states, "There are no features to suggest underlying olfactory neuroblastoma; however, the material may not be representative of the entire tumor." The managing physician states this is most consistent with olfactory neuroblastoma (esthesioneuroblastoma) in the medical record.

If this were a mixed histology tumor, there is no applicable H Rule in the Head & Neck schema. It is unclear which biopsy diagnosis to use since there is conflicting information. Should this be coded as an olfactory neuroblastoma per the initial biopsy diagnosis and the diagnosis provided by the physician? Or should this be a high grade neuroendocrine carcinoma as it is likely the tumor component with the worst prognosis?

Patient is diagnosed with adenocarcinoma documented by the physician as “colorectal cancer.” The medical record does not specify colon, rectosigmoid, rectum, or any specific segment of the large intestine. There is also no imaging, operative, endoscopic, or pathology documentation identifying a more precise site of origin.

Specifically, should the registrar assign:

· C18.9 — Colon NOS - (excludes rectum, NOS C20.9 and rectosigmoid junction C19.9)

· C19.9 — Rectosigmoid junction

· C20.9 — Rectum NOS

· C26.0 — Intestinal tract, NOS

· C26.9 — Gastrointestinal tract, NOS

· or another site

A right breast lumpectomy identified a spindle cell neoplasm with CLCN6::BRAF fusion. The diagnosis comment states, "There is limited data on spindle cell neoplasms with this specific fusion, therefore the outcome/malignant potential is unclear. The lesion is well circumscribed with low grade morphology but shows increased cellularity and mitotic activity that reaches 40 mitoses per 10 high power fields, which may be better considered as sarcoma for therapy purposes.” The physician clinically calls it a spindle cell sarcoma. Is this a reportable emerging sarcoma histology?

SEER*Rx categorizes Thyrogen as Hormones and hormonal mechanisms/Thyroid stimulating hormone. Probably not cancer directed–verify with attending MD.