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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).

Assign the highest code with 51 as the highest and 10 the lowest when there is more than one test performed with differing results.

The SEER Manual will be updated in the 2025 release. SEER*RSA will be updated in a future release, version 3.3 in 2026, as version 3.2 has been updated for 2025.

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 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.

HGAP is listed as a separate classification and is not a subtype of the diffuse gliomas. WHO Classification of Tumors of the Central Nervous System, 5th edition, has two categories dealing with non-pediatric astrocytic tumors:

Adult-type diffuse gliomas

Circumscribed astrocytic tumors

HGAP falls into the second category as a result of updates to the 4th edition WHO classification in 2016 with advances in the role of molecular diagnostics with the 5th edition. All astrocytic tumors were previously grouped together whereas not all diffuse gliomas (astrocytic or not) are grouped together on the basis of growth pattern and behaviors, and shared IDH1 and IDH2 genetic status. The new classification separates astrocytomas that have a more circumscribed growth pattern, lack IDH gene alterations, and sometimes have BRAF mutations (i.e., pilocytic astrocytoma). The impact of molecular advances has driven classification changes as described in the 5th edition.

Review of site/histologiy combinations for CNS neoplasms is currently being performed by Cancer PathCHART experts. It's possible they will recommend HGAP be moved to a subtype/variant of astrocytoma, NOS. 

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.

Assign histology code 8254/3 (mixed invasive mucinous and non-mucinous adenocarcinoma) to this lung tumor using Lung Solid Tumor Rules, Rule H4. This is a new code/term approved by IARC/WHO for ICD-O. Rule H4 instructs one to code the histology when only one histology is present. In this case, the pathologist indicates the tumor is mixed mucinous and non-mucinous histologies. The non-mucinous carcinoma that is seen in this mixed histology may be identified as: Adenocarcinoma in situ, minimally invasive adenocarcinoma, or lepidic predominant adenocarcinoma. In this case it is lepidic predominant adenocarcinoma. Lepidic is a recognized histology in lung. It is not unusual for the pathologist to indicate mixed non-muncinous and mucinous adenocarcinoma AND also list the non-mucinous subytpe. It is important to capture both mucinous and non-mucinous histologies which drives treatment, etc. 

Assign 8140/3 (adenocarcinoma, NOS). WHO has not yet recognized the variant amphicrine prostate carcinoma and have not proposed an ICD-O code for this neoplasm. Document information in a related text field.

Assign code 40, Pull through WITH sphincter preservation (colo-anal anastomosis).  The National Cancer Institute Dictionary of Cancer Terms defines coloanal anastomosis as a surgical procedure in which the colon is attached to the anus after the rectum has been removed. It is also called coloanal pull-through.

For cases diagnosed in 2023 and later, Update to the current manual: Assign code 13 (Radioisotopes, NOS) in Radiation Treatment Modality--Phase I, II, III for PRRT.

We will make this change in the next version of the SEER Manual.