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Code Primary Site to C480 (retroperitoneum). 

Endometrial tissue may "break away” from the uterus and implant throughout the pelvic and abdominal cavities. This can occur in patients who suffer from endometriosis. This tissue remains behind when surgical removal of the uterus is done. Common sites of implantation are colon, peritoneum, retroperitoneum, and bladder. These cells may become malignant. When the uterus is no longer present (patient had surgical removal), code the site where the carcinoma was identified.

The site-morphology combination of C480 and 8380/3 was designated as an unlikely site-morphology combination by the Cancer PathCHART expert pathologist review, as this is a rare type of tumor. Assign a value of 1 in the Over-ride Site/Type [2030] data item in order to pass the Primary Site, Morphology-Type, Beh ICDO3, 2024 (SEER) edit.

Code as a localized, intracapsular tumor as ductal carcinoma in situ does not invade. Intraductal spread is describing the neoplasm spreading through the acinar/ductal cells in the prostate specimen. It is an in-situ type of spread and not invasive but almost always presents with an invasive tumor.

Assign histology as 9982/3 (myelodysplastic neoplasm with low blasts and SF3B1 mutation). This is a new term for 9982/3. WHO Classification of Hematolymphoid Tumors, 5th edition, defines myelodysplastic neoplasm (MDS) with low blasts and SF3B1 mutation (MDS-SF3B1) as a myeloid neoplasm with cytopenia and dysplasia characterized by SF3B1 mutation and often ring sideroblasts.

Code as an oropharyngeal primary site and histology as solitary plasmacytoma (9734/3) based on consultation with our hematological expert.

The WHO Classification of Hematopoietic and Lymphoid Tissues defines multiple myeloma as "bone marrow plasma cell percentage >60%." There are several other factors, but the bone marrow involvement is the key point for your case. The pathologist also states that the bone marrow is consistent with "plasma cell neoplasm," which by itself is not the same as multiple myeloma.

This case has 5-10% involvement by plasma cell neoplasm. This does not meet the bone marrow qualifications for multiple myeloma and is consistent with the pathologist's statement that there is minimal bone marrow involvement.

We will be updating the Hematopoietic and Lymphoid Neoplasms Database and Manual to clarify this (2025 updates).

Report this case of leukemia cutis and code to bone marrow (C421) and leukemia NOS (9800/3) based on the information provided. Update the abstract if new information becomes available.

Leukemia cutis is the rare infiltration of neoplastic leukocytes into the epidermis, dermis, or subcutis from an existing leukemia that results in clinically identifiable cutaneous lesions. Leukemia cutis may precede, follow, or occur concurrently with the diagnosis of systemic leukemia. It is an advanced phase of the leukemia having a poor prognosis that also strongly correlates with additional sites of extramedullary involvement. This can alter the appropriate treatment regimen for a patient. It is a type of "metastasis" or spread of the leukemia cells. The "conventional" definition for leukemia cutis is the infiltration of skin from a bone marrow primary. It is most often diagnosed via skin biopsy—punch, shave, etc., utilizing IHC/biomarker testing and is commonly associated with CMML and acute myeloid leukemia (AML). As such, it a reportable condition especially when preceding a confirmed systemic leukemia diagnosis. In this situation, the diagnosis date would be the date of the positive leukemia cutis skin bx—punch, shave, etc. The case should be coded to C421; 9800/3 Leukemia NOS until the official systemic leukemia diagnosis is rendered. If possible, follow back should be conducted to determine the specific systemic leukemia histology (CMML; AML) and the treatment received. If the leukemia cutis follows or occurs concurrently with the diagnosis of a systemic leukemia, it is NOT a separate primary but merely an advanced stage of the systemic leukemia diagnosis.

Assign histology as 8072 for non-keratinizing SCC, undifferentiated subtype.

 WHO Classification of Head and Neck Tumors, 5th edition assigns 8072/3 to squamous cell carcinoma, non-keratinizing, NOS in the nasopharynx. As the tumor exhibits a variety of architectural patterns and appearances histologically, they can be further classified as undifferentiated or differentiated subtypes. These subtypes do not change the histology code.

Lymphoepithelial carcinoma is a subtype of SCC usually seen in skin or H&N sites and often associated with EBV. CPC SME review determined 8082/3 invalid for breast but did not recommend a substitute code. There were only 45 cases coded 8082 2001 to 2019. For this case, it's possible the lesion originated in the breast skin and progressed to breast tissue. SCC is a subtype of metaplastic breast carcinoma so one could argue it code be coded either 8575 or 8070. For this case, we recommend assigning 8500/3. Use text fields to record the details.

Assign histology as DLBCL (9680/3) as supported by the WHO Classification of Hematolymphoid Tumors, 5th edition. It is consistent with how it would have been coded in the 4th edition. The Heme Manual and Database currently are based on the 4th edition. Physicians are using the 5th edition blue book, whereas the cancer registry field is not yet at this time.

Regarding the Heme Manual and Database, this type of scenario is not covered because it is part of the 5th edition WHO Blue Book. The database cannot be updated until the 5th edition is approved for implementation (2026).

Abstract as bone metastasis for the first two examples. Abstract as both bone and brain metastasis for the third and fourth examples in the respective Mets at Diagnosis fields based on the description provided.

The CPC ICD-O-3 Site Morphology Validation Lists (SMVLs) designate all tumor site-morphology combinations that are either valid or impossible as determined for the sites reviewed by the Cancer PathCHART initiative. These lists provide information on the Validity Status of specific tumor site and morphology combinations, similar to the way the ICD-O-3 SEER Site/Histology Validation List used to. However, the CPC SMVLs do not include information on the reportability of specific tumor site and morphology combinations. For tumor reportability, you will continue to use the Excel ICD-O-3.2 spreadsheets posted to the NAACCR ICD-O-3 Coding Updates website: https://www.naaccr.org/icdo3/, and the most recent SEER Manual and federal, state, local, and other standard setters' reportability requirements.