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The ICD-O-3.2 Coding Table includes Mullerian mixed tumor as the preferred term for histology code 8950 (previously malignant mixed Mullerian tumor/MMMT). This table also includes carcinosarcoma, NOS as the preferred term for histology code 8980. Neither the ICD-O-3.2 Coding Table nor the Implementation Guidelines address the long-standing issue of coding histology for diagnoses of carcinosarcoma/malignant mixed Mullerian tumor.

These endometrial primaries are frequently diagnosed as both carcinosarcoma and MMMT. The questions regarding histology coding for carcinosarcoma and carcinosarcoma/MMMT of the endometrium date back to before the Multiple Primaries/Histology Rules, with at least three SINQ entries instructing registrars not to use code 8950/3 (MMMT) for diagnoses of MMMT. SINQ has instructed registrars that MMMT is a synonym for carcinosarcoma and these tumors should be coded to 8980 (carcinosarcoma), not to 8950 (MMMT). The most recent SINQ is partly inconsistent with the others, indicating 8950 can be used if the tumor is only described as MMMT. The other SINQ entries state carcinosarcoma should be used as it is the preferred term for MMMT. (See SINQ 20061008, 20100009, 20180071.)

The most recent SINQ (20180071) specifically indicates: According to the WHO Classification of Tumors of Female Reproductive Organs, 4th edition, MMMT (8950/3) is now a synonym for carcinosarcoma (8980/3) even though it has a separate ICD-O code. The ICD-O code for MMMT is no longer in the WHO book. However, MMMT is in the ICD-O-3.2 Coding Table and is not stated to be obsolete or a synonym. Which is correct, the clarification in the SINQ or the 2021 ICD-O-3.2 Coding Table?

For a 2021 diagnosis of carcinosarcoma/malignant mixed Mullerian tumor, how should registrars code the histology? Follow the previous SINQ entries and Rule H17 to code the histology to 8980 when the diagnosis includes both carcinosarcoma and MMMT? Do these previous SINQ entries still apply to cases diagnosed 2021 and later?

This question was prompted from preparing SEER*Educate coding exercises. We will use the answer as a reference in the rationales.

Lung Rule M14 appears to be the first rule that applies to this case and instructs the user to abstract a single primary. However, we were hoping for confirmation that a cancer (NOS) or malignancy (NOS) would not be a distinctly different histology that may qualify for Lung Rule M8. Currently, these histologic terms are not included in the Table 3 options or mentioned in the preceding notes.

Per the site validation list: https://seer.cancer.gov/icd-o-3/sitetype.icdo3.20190618.pdf#search=site%20validation, ill-defined sites (ILL-DEFINED C760-C768) does not include 8070- Squamous cell carcinoma as a valid histology. Therefore when a Cervical Lymph Node and Unknown Primary Tumor of the Head and Neck is submitted with a C760 and 8070/3, it requires an override be set.

We think this should be a single primary because the Solid Tumor rules do not apply to metastases. However, we are not sure whether or not the instructions outlined for prostate (SINQ 20180088, 20130221), that indicate we are to accession a new metastatic tumor only with a small cell neuroendocrine histology after an adenocarcinoma, also applies to lung primaries.

We are aware of a phenomenon in which lung adenocarcinoma cases treated with Erlotinib can transform to small cell, but do not know whether it impacts the number of reportable primaries.

2020 Diagnosis: Patient had a right hemicolectomy showing adenocarcinoma of cecum, tumor extends into proximal portion of attached vermiform appendix. Tumor invades through muscularis propria into pericolorectal tissues (NOS). Regional lymph nodes: 06/39. Primary Tumor EOD: Where does the appendix involvement come into coding or will this be based on the pericolorectal tissue (NOS) invasion? What is my Summary Stage? I know it is at least 3 due to regional ln involvement, but the appendix involvement is making me question 3 vs 4.

The patient was diagnosed with an EBV-positive plasmablastic lymphoma involving the left testis on radical orchiectomy in April 2019.

In September 2019, a plasmacytoma was found on a right mandibular mass biopsy. Imaging at that time revealed diffuse disease involving the thoracic spine and sinus involvement. The patient then underwent a resection of the T8 spinal/epidural tumor that also proved plasmacytoma.

Subsequently, the right mandibular mass and testis slides were reviewed (at an outside facility) and both were stated to be, The T8/epidural tumor pathology was not reviewed, so it is unclear if this is also assumed to be the same disease process as the right mandibular mass or still a separate, solitary plasmacytoma.

Additionally, some chart notes indicate the patient has plasmablastic lymphoma with a secondary diagnosis of plasmacytoma, while other chart notes state this is stage IV plasmablastic lymphoma involving all documented sites. Although the plasmablastic lymphoma and at least the plasmacytoma of T8 have different ICD-O-3 histology codes, the physicians do seem to be treating this as a single disease process.

The Terms and Definitions Introduction discusses how these are older terms, but pathologists may still use them. In our region, pathologists do, in fact, still use these terms. Can these terms be added to Table 1? For registrars who do not reference the Introduction every time they code histology but go directly to Table 1, coding consistency would likely improve if such terms were added in the Table.

This question was prompted from preparing SEER*Educate coding exercises. We will use the answer as a reference in the rationales.

Path report reads: 7/15/2019 A. Endometrium, curettings: Serous carcinoma, high grade. B. Endometrial polyp, curettings: Serous carcinoma, high grade.

If coded to 8461/3, according to AJCC, this would not be an ideal code (since it is outdated). Also, endometrium is not included in the suggested site codes for 8461/3 according to the 8/22/2018 ICD-O-3 update.