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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.

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.

The ICD-O-3.2 Implementation Guidelines and ICD-O-3.2 Coding Table indicate that insulinoma, NOS has changed behavior from /0 to /3 for cases diagnosed 2021 and later. However, the ICD-O-3.2 Implementation Guidelines do not indicate whether this change applies to tumors described as above. Insulinomas are generally neuroendocrine tumors/neoplasms, so it seems any neuroendocrine tumor described as an insulinoma should be collected as 8151/3, but does that apply to an epithelioid tumor/neoplasm also described as insulinoma?

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

The ICD-O-3.2 indicates histology 8051 only applies to diagnoses of condylomatous carcinoma and warty carcinoma made prior to 2018. For penis cases diagnosed 2018 and later, these neoplasms should be coded as 8054. This is consistent with SINQ 20200003.

However, a new Table was added to the Other Sites schema in the 2024 Solid Tumor Rules update. Table 23 lists “Verrucous carcinoma / carcinoma cuniculatum / Warty carcinoma” as histology 8051. While verrucous carcinoma is still listed under histology 8051 in the ICD-O-3.2, warty carcinoma is not.

Does Table 23 need to be updated? Or is this an error in both the ICD-O-3.2 and SINQ 20200003?

The language appears similar to the mucinous cystic neoplasm of the pancreas with high grade dysplasia (8470/2), which was clarified to be reportable in 2014.

The left thyroid lobectomy/isthmusectomy returned a diagnosis of sclerosing mucoepidermoid carcinoma with eosinophina, 6.5 cm, replacing nearly the entire left lobe of the thyroid.

The patient has a completion thyroidectomy of the right lobe and returned the diagnosis of papillary thyroid carcinoma, 0.5 mm, in maximum dimension.

The endocrinologist describes it as "co-exsisting" and states the tumor is iodine non-avid.

The managing physician has staged this pathologically as T4 N0 M0 squamous cell carcinoma of the ethmoid sinuses. The final pathology report says " Sinus, sphenoid, resection: papillary neoplasm most consistent with inverted papilloma with squamous cell carcinoma in situ, 7 cm in greatest extent, focus of probable superficial invasion (see comment).

Soft tissue, skull base, excision: involved by papillary neoplasm with squamous cell carcinoma in situ (see comment). Brain, extradural, intercranial biopsy: involved by papilloma with squamous cell carcinoma in situ. COMMENT:

This is a predominantly exophytic neoplasm with infolding of the tumor epithelium and in situ extension into submucosal glands. There are only focal areas suspicious for invasive squamous cell carcinoma, with probable invasion (<2mm) in one section....The histologic features are most consistent with an inverted papilloma with carcinoma in situ." When asked to comfirm if the diagnosis were in situ or superficially invasive, the pathologist responded "Squamous cell carcinoma in situ involving a papilloma. Locally aggressive but not technically invasive."

The mediastinal nodes were submitted as a separate specimen. The patient also had several peribronchial nodes identified within the lobectomy specimen.

Does code 33 (Lobectomy with mediastinal lymph node dissection) require a complete mediastinal lymph node dissection (i.e. the removal of all lymph nodes in mediastinal chain(s) as opposed to a selective sampling/dissection of lymph nodes from multiple mediastinal chains)?

The most recent version of the Brain Site Specific Surgery schema has a note that states "Assign code 20 [Local excision of tumor, lesion, or mass, excisional biopsy] for stereotactic biopsy of brain tumor." Does this also apply to a stereotactic CORE biopsy?

SINQ 20081118 also states that a stereotactic biopsy should be coded as Surgery of Primary Site code 20.

The MP/H Equivalent Terms and Definitions for Colon indicate that type, subtype, predominantly, with features of, major, or with ___ differentiation are all equivalent in terms of coding histology. However, this is not indicated in the General Instructions (e.g., Histologic Type ICD-O-3 or General Instructions Histology Coding Rules). It also is not included as a Note under the Rules where one would expect to use these terms, for example, Rule H7. Is this an oversight or error in the Manual?

In this case, Rule H7 seems to be the first (and most appropriate) rule that applies to this mixed histology tumor. However, the specific histology terms that an invasive tumor may be identified as, are only listed under Rule H13. Can these same terms be used when applying rules for which they are not specifically noted? It would seem logical to use the equivalent histology terms to code a mixed histology tumor identified as a subtype or with features, etc., despite the fact that the specific terms are not listed under Rule H7.