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A patient had posterior cervical lymphadenopathy status post biopsy and subsequent lymph node dissection showed metastatic melanoma in 2018. Workup showed no skin lesions or primary site. Final diagnosis is melanoma of unknown primary (unknown if cutaneous or non-cutaneous). Should C760 be used as the primary site for this case since the histology codes of 8700-8790 are included in the Cervical Lymph Nodes and Unknown Primary Tumors of the Head and Neck schema in SEER*RSA?

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.

While we recognize the Heme DB has been the correct source for histology coding for heme and lymphoid neoplasms dating back to 2010, the ICD-O-3.2 Implementation Guidelines appear to provide incorrect coding instructions. Histologies 9670/3, 9728/3, 9729/3 and 9836/3 are listed in Table 3 - Deleted ICD-O codes in ICD-O-3.2.

While we recognize these histologies have been included in this Table because they have now been deleted, it is unclear whether the Comments regarding their use listed in the 4th column of the Table is correct. For each of these histologies, the comment states the histology listed in the 1st column (ICD-O-3/3.1) should be used prior to 2021. For example, for histology 9670/3, the comment states: Cases diagnosed prior to 1/1/2021 use code 9670/3. Cases diagnosed 1/1/2021 forward use code 9823/3. However, each of these histology codes have been obsolete for cases diagnosed 1/1/2010 and later. If registrars were following the Heme DB and Heme Manual instructions (the appropriate coding source for these neoplasms), these histologies would not have been used in a decade.

Should the Comments column in Table 3 be updated? Or should a Note follow the Table indicating registrars should not use these histology codes for cases diagnosed after 1/1/2010, and these histology codes have been deleted for cases diagnosed 1/1/2021? It seems misleading to indicate any of these are valid histology codes for a 2010-2020 diagnosis when the Heme DB confirms these histology codes only apply to cases diagnosed prior to 2010.

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.

Penile mass excision shows final diagnosis of squamous cell carcinoma, verrucous type. Subsequent partial penectomy has a final diagnosis of squamous cell carcinoma, verrucous type and the summary cancer data lists

Both the final diagnosis and summary cancer data indicate a histology code of 8051/3 (squamous cell carcinoma, verrucous type / verrucous carcinoma). However, this site and histology combination triggers edit IFN4911. Edit documentation indicates that for sites C600-C609 (all penile sites) use histology code 8051 and do not use 8054.

Review of the 2018 ICD-O-3 Histology Updates table does not indicate these terms are synonymous.

For example, a patient has a 2.6 cm breast tumor on MRI; a core biopsy measuring 0.7 cm is positive for infiltrating duct carcinoma. Rule #1 states "Use the largest measurement of the primary tumor from physical exam, imaging, or other diagnostic procedures before any form of treatment." However, Rule #9 seems to imply that size from an "incisional biopsy" takes precedence over imaging, even though it is known to be less than the entire tumor in size.

Is this histologic terminology synonymous with 8071/2 Differentiated-type vulvar intraepithelial neoplasia?

Per the 7/20/2018 updates to the 2018 ICD-O-3 Histology list, the reportability flag was changed from N to Y for Differentiated-type vulvar intraepithelial neoplasia as well as Differentiated penile intraepithelial neoplasia, both 8071/2. It appears that both SINQ 20180020 and the second half of SINQ 20160069 are no longer valid and should be deleted.

The ICD-O-3.2 Coding Table includes hybrid oncocytic chromophobe tumor as a related term for histology code 8317 (Renal cell carcinoma, chromophobe type). However, this related term is not discussed in the implementation guidelines as being a new term/reportable tumor. The Solid Tumor Rules do not indicate a hybrid oncocytic chromophobe tumor is reportable; however, if a registrar only looked at the ICD-O-3.2 Coding Table, it may seem as though this histology should be collected.

The term hybrid oncocytic chromophobe tumor was not included in the Solid Tumor Rules as a subtype/variant of RCC, or as an equivalent term for chromophobe RCC. There is a SINQ (20180047) that states not to report renal hybrid oncocytic tumor, despite the fact these tumors exhibit mixed features of both oncocytoma and chromophobe RCC. For cases diagnosed 2021 and later, should the clarification in the SINQ apply? Or should the ICD-O-3.2 Coding Table be used which indicates this is a reportable diagnosis? If the standard setters decided not to implement use of hybrid oncocytic chromophobe tumor for 2021, can clarification be added to the Solid Tumor Rules or Implementation Guidelines?

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