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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.

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.

Assign 8077/2 for high-grade squamous intraepithelial lesion, VIN 3 in this case.  The WHO Classification of Female Genital Tumors, 5th edition, states that squamous intraepithelial lesions (SILs) of the vulva are also known as vulvar intraepithelial neoplasia, HPV-associated.  The term squamous cell carcinoma in situ is not recommended.

Code Primary Site as Overlapping lesion of cervix uteri (C538). The 2023 SEER Program Coding and Staging Manual Primary Site Coding Instructions for Solid Tumors #4 says to code the last digit of the primary site code to ‘8’ when a single tumor overlaps an adjacent subsite(s) of an organ and the point of origin cannot be determined. This is also supported by the ICD-O-3, 3rd edition, note in the Topography section that states: In categories C00 to C809, neoplasms should be assigned to the subcategory that includes the point of origin of the tumor. A tumor that overlaps the boundaries of two or more subcategories and whose point of origin cannot be determined should be classified to subcategory ‘8.”

This is reportable as 9591/3, B-cell lymphoma, NOS.All diagnoses in the differential are all B-cell lymphomas. The pathologist knows it a B-cell lymphoma but has not determined the subtype. If at a later time a specific lymphoma is determined, update the histology code accordingly. 

Your case is equivalent to encapsulated follicular variant of papillary thyroid carcinoma, non-invasive (non-invasive EFVPTC) and is not reportable for cases diagnosed in 2021 or later even though it says "carcinoma." That is because the WHO assigned a behavior code of /1 to this entity (8349/1). NIFTP is assigned to the same histology and behavior code.

Abstract a single primary using Breast Solid Tumor Rules, Rule M18, as none of the previous rules apply.

Undifferentiated carcinoma is a malignant epithelial tumour lacking overt evidence of a specific line of differentiation. Dedifferentiated carcinoma is composed of an undifferentiated carcinoma and a differentiated component. Dedifferentiated carcinoma (8020/3) as a morphology is associated with cancer of the endometrium and ovary rather than the breast.  Breast cancer shows a broad spectrum of morphology with extensive variation in histological type and grade, related to the complexity of carcinogenesis.  This includes initial genetic changes in the cell of origin, subsequent genetic and epigenetic alterations, and reprogramming that occur at various stages of development along with interaction of other factors that influence the process of differentiation.  This scenario likely represents the process of phenotypic change of a carcinoma at a later stage, better known as transdifferentiation.

Abstract a single primary and assign code 9700/3 for MF.  According to our subject matter expert, this is all MF.  When MF progresses, there can be large cd30 positive T cells. This is not the same as anaplastic large cell lymphoma.

Assign code 17 for irreversible electroporation ablation of the prostate when there is no tissue submitted to pathology for a 2021 or 2022 case.

Assign code A170 for a 2023 case.

Table 19 is based on WHO 5th Ed Tumors of vulva and squamous cell variants, keratinizing and non-keratinizing, are no longer recommended and are excluded from the 5th Ed. HPV related terminology is now preferred for these neoplasms.

Per consultation with our GYN expert pathologist, based on the information provided, this is likely a single tumor that was not completely excised in the original biopsy. A new tumor in the same site would not appear within 8 months. If you cannot confirm two separate/non-contiguous tumors were present, abstract a single primary per M1. As for histology, the tumor showed both keratinizing and non-keratinizing features and HPV status is unclear. Per our expert, code to SCC 8070/3—keratinization or lack of does not change treatment or prognosis.

Even If there is proof of separate/non-contiguous tumors, our expert still feels this is a single primary coded to SCC 8070/3. Treatment does not differ by keratinization or HPV status. Coding two primaries would be incorrect and inflate incidence rates.

Per our expert, this is an unusual occurrence. The rules cover 85% of cases but there will always be situations that do not fit a rule. This case is an example of that.  A new GYN specific Solid Tumor Rules module is under development and a rule to address this situation could be included.