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Abstract a single primary using Solid Tumor Rules, Malignant CNS and Peripheral Nerves, Rule M10 based on the information provided.  Rule M10 applies as both non-contiguous tumors are of the same histology; i.e., on the same row in Table 3. As MPNST can arise in many sites, look for information about the precise location and tissue type in which the tumor arose. For example, if the tumors are stated to arise in soft tissue, follow the Multiple Primary Rules for Other Sites.

Both WHO Classification of Central Nervous System Tumors and WHO Classification of Soft Tissue and Bone Tumors state that MPNST is a malignant spindle cell tumor often arising from a peripheral nerve, from a pre-existing benign nerve sheath tumor, or in a patient with neurofibromatosis type 1 (NF1).

Future updates will move C470-C479 from CNS to other sites module.

Assuming the smal cell is a seperate tumor, accession two primaries, adenocarcinoma (8140/3) of the prostate and SmCC (8041/3) of the prostate using Rule M19 of the current Other Sites Solid Tumor Rules.  As these two tumors are less than a year apart, Rule M4 does not apply; however, Rule 19 does apply as these are two distinct histology types. It takes time for an acinar tumor to transform into the small cell and it is usually triggered by hormone and/or radiation treatment. 

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.

Code the Date of First Surgical Procedure as 01/01/2023 in the example provided where the shave biopsy is followed by wide excision. Beginning in 2023, significant changes were made in that shave, punch, and elliptical biopsies are coded as surgical procedure regardless of margin status. Appendix C Skin Surgery Codes state that an incisional biopsy would be a needle or core biopsy of the primary tumor.

Please see Appendix M: Case Studies for Coding Melanoma in STORE v23, Case study 2: Shave Biopsy followed by WLE (page 412), for an explicit example of how to code your example case.

We will clarify this in the upcoming release of the SEER manual,

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.

Report as squamous cell carcinoma (8070/3) on the basis of “microscopic focus suspicious for superficial invasion.” "Severe dysplasia" is equivalent to "high grade dysplasia" in the Head and neck. As such, "severe squamous dysplasia" would be coded to 8077/2. However, in combination with the statement of "with microscopic focus suspicious for superficial invasion,” report as squamous cell carcinoma (8070/3) based on “microscopic focus suspicious for superficial invasion.” The 2023 SEER Manual instructs us to code the behavior as malignant (/3) if any portion of the primary tumor is invasive no matter how limited, i.e., microinvasion. Use text fields to record the details. 

Yes. DFSP with fibrosarcomatous overgrowth and DFSP with fibrosarcomatous component Grade 2 are synonymous with fibrosarcomatous DFSP (8832/3).  Our expert pathologist also advises that DFSP with focal myxoid features is the same as DFSP, myxoid (8832/3).

Assign margin status as “positive” when stated as approximates margins as recommended by our expert pathologists. Approximating means coming right up to inked margin without the margin transecting the tumor.

Primary site would be C421 based on Hematopoietic and Lymphoid Neoplasm Manual, Module 3, Rule PH 5.

Assign EOD Primary Tumor to code 800 (peripheral blood involvement WITH other involvement).

Per consultation with an expert hematologist oncologist, this is a Stage IV CLL/SLL since the peripheral blood is involved. There is no cutoff value for the abnormal B-cell populations in the peripheral blood when the cells are consistent with CLL/SLL. If the peripheral blood is involved, even only slightly, it is a Stage IV CLL/SLL. Our expert stated that the physician's staging was wrong (this is not a Lugano, Stage III).

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.