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This case does not fall into the standard rules. WHO criteria for diagnosing pituitary adenoma have recently changed (per 5th Ed WHO CNS book) and we will likely see more PitNET’ s than pituitary adenomas in the future.  PitNET may be invasive or non-invasive but the likelihood of the pathologists providing this information is low. Since we don’t know if the 2018 adenoma was a PitNET based on current criteria or if it transformed to the malignant neoplasm, err on the side of caution and abstract a second primary per M5.

This issue is new, and we’ve received numerous questions concerning pathologist reviewing older cases of pituitary adenoma and reclassifying them as PitNET using the new criteria.

Abstract multiple primaries using the Solid Tumor Rules, Other Sites, Rule M13.  The topography differs at the second and third characters (C54.1 Endometrium; C15 Esophagus).  Rule M12 refers to being disease-free vs. recurrence of a tumor, where Note 1 states that clinically disease-free means no evidence of recurrence in the same site on follow up.

A note can be added to clarify that M12 applies to new tumors in the SAME site.

NTRK-rearranged spindle cell neoplasm is a newly identified variant of sarcoma; however, WHO has not yet proposed a specific ICD-O code for this rare neoplasm. Code to spindle cell sarcoma (8801/3).

WHO defines NTRK-rearranged spindle cell neoplasm as an emerging group of molecularly defined rare soft tissue tumors that span a wide group of morphologies and histological grades, and are most often characterized by a spindle cell phenotype among other characteristics.

For the example provided: For 2023 cases and forward, if no part of the surgery was performed, code Surgery of Primary Site 2023 (NAACCR Item #1291) as code A000 or B000 (no surgical procedure of the primary site).  Code Reason for No Surgery of Primary Site (NAACCR Item #1340) as code 2 (surgery of the primary site was not recommended/performed because it was contraindicated due to patient risk factors (comorbid conditions, advanced age, progression of tumor prior to planned surgery, etc.).

In contrast, if any part of the surgery was performed, assign the Surgery of Primary Site 2023 (NAACCR Item #1291) code that best reflects the extent of the surgery performed.  Code Reason for No Surgery of Primary Site (NAACCR Item #1340) as code 0 (surgery of the primary site was performed).

Use text fields to record the details.

For cases prior to 2023, apply the same approach using Surgery of Primary Site (NAACCR Item #1290) instead of Surgery of Primary Site 2023 (NAACCR Item #1291).

Abstract two primaries using the 2023 Solid Tumor Rules, Other Sites, Rule M19, as adenocarcinoma and pancreatic neuroendocrine tumors are two distinct histologies.  The WHO Classification of Digestive Tumors, 5th ed., Chapter 10-Tumors of the Pancreas, lists both epithelial tumors and neuroendocrine neoplasm as separate entities.  The Solid Tumor Rules histology-specific tables contain histologies that commonly occur in the 19 site-specific histology tables; therefore, not all histologies are listed in the rules. Further, the adenocarcinoma would be staged in the Pancreas Schema, while the neuroendocrine tumor would be staged in the NET Pancreas schema.

We will consider adding PanNETs to Table 11 in a future release of the Solid Tumor Rules.

Answer updated April 2025

A change in the subcategory for a hormone drug does not indicate the end of First Course of Treatment because different hormone therapies generally achieve the same result. For example, some forms of breast cancer are estrogen-dependent and the various subcategories of hormone drugs used to treat them, such as gonadotropin-releasing factor agonists, aromatase inhibitors and estrogen antagonists, all achieve the same result - to block estradiol effects in these tumors.

Similarly, a change in immunotherapy is not a new course of treatment.

However, if a change to hormone therapy or immunotherapy is due to a change in the patient's ER, PR, or Her2 status, this could signify a new course of treatment.

The instruction in the SEER Manual is specific to chemotherapy. Chemotherapy is the only systemic treatment for which a change in the subcategory of a drug indicates the end of First Course of Treatment, due to the fact that different chemical agents damage cancer cells in different ways and at different phases in the cell cycle.

Abstract two primaries using rule M4 of the Colon rules or rule M13 of Other Sites: 1. Invasive adenocarcinoma of distal rectum and 2. Paget disease of the anal mucosa / perianal skin (determine site of origin and code primary site accordingly). The rectum and the anus are separate sites and the histologies differ in each site.

The WHO Classification of Digestive System Tumors, 5th edition, states that in addition to secondary anal Paget disease arising from anal canal adenocarcinoma, or rarely, adenoma without documented invasive disease, secondary Paget cells may be contiguous with the underlying neoplasm or manifest at different at sites distinctly away from it (with skip lesions).  Document the details in the appropriate text fields.

Assign histology as 9505/3.  WHO Classification of Central Nervous System (CNS) Tumors describe ganglioglioma as a well-diffferentiated and slow-growing glioneuronal neoplasm.  While WHO does not recognize the histology/behavior combination 9505/3, the 2021 CNS Solid Tumor Rules identify non-malignant tumors that have the potential of transforming to a malignant tumor (new primary).  Ganglioglioma (9505/1) is listed with the transformed histology and instructs us to code as anaplastic ganglioglioma (9505/3).

Based on the diagnosis date for the unknown primary, use the 2007 MPH Other sites rules. Since the site codes differ for each primary, rule M11 applies, abstract two primaries.

In the absence of information to the contrary, thyroid FNAs designated as Bethesda classification category VI are reportable. Thyroid FNAs designated as Bethesda classification category V are not reportable unless there is additional information confirming a reportable diagnosis. For both Bethesda V and VI, NCCN Guidelines recommend total thyroidectomy or lobectomy (depending on tumor size and nodal involvement) for the purposes of definitive diagnosis/treatment, so additional information should be available.

We will add this to the next version of the SEER manual.

In your example, nodule 1 Bethesda V is not reportable. Nodule 2 Bethesda VI is reportable.