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Rule H6 states: Code 8742/3 (Lentigo maligna melanoma) when the diagnosis is lentigo maligna melanoma with no other histologic types. However, if the diagnosis was strictly lentigo maligna or lentigo maligna melanoma, the first rule that applies is Rule H1 because lentigo maligna melanoma is a single, specific histologic type and Rule H1 states, Code the histology when only one histologic type is identified. Following the current rules, one would never arrive at Rule H6. Should the H Rules be reordered? Or should an example of when one would use Rule H6 be added to clarify when to use this rule?

Kidney, right interpolar neoplasm, partial nephrectomy: Oncocytic renal neoplasm of low malignant potential (ORNLMP).

Within part B, right interpolar kidney neoplasm, the neoplasm shows oncocytic features, with abundant granular eosinophilic cytoplasm and enlarged vesicular nuclei with prominent central nucleoli. The cells are arranged in small nests and tubules with hypocellular fibrous stroma identified within the background. Scattered binucleated cells are present, and rare cells with irregular nuclear membranes are present. No perinuclear halos or prominent cell membranes are present. Given the histologic features, the neoplasm is best classified as an oncocytic renal neoplasm of low malignant potential (ORNLMP).

Recognizing the addition of the behavior requirement into this rule is an attempt to stop non-synchronous ductal carcinoma and lobular carcinomas from being accessioned as a single primary (SINQ 20200022), the issue with using behavior rather than timing is that now, synchronous separate/non-contiguous tumors that are invasive carcinoma NST (8500/3) and lobular carcinoma in situ (8520/2) (or vice versa) are separate primaries per M14.

Lobular and carcinoma, NST are separate rows in Table 3, so we cannot stop at M10 and code the mixed histology because there are two separate histologies with different behaviors. There is no rule that states we can just ignore the in situ tumors for the purpose of applying the M Rules. (We are instructed to ignore the in situ when coding histology only in certain circumstances.) The problem with Rule M10 appears to be related to timing.

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

Rule H13 states to code the histology to metaplastic carcinoma when there is metaplastic carcinoma (or a subtype/variant) and invasive carcinoma NST. This rule makes no mention of lobular carcinoma. However, in Table 3, Note 2 for metaplastic carcinoma (8575) states metaplastic carcinoma, NOS and subtypes are almost always mixed with invasive mammary carcinoma, NST and at times lobular carcinoma. These tumors should be coded to metaplastic regardless of percent invasive mammary carcinoma or lobular carcinoma present.

While Table 2 (the mixed histology code table) does include an entry for metaplastic carcinoma AND carcinoma NST OR lobular carcinoma, it is unclear why lobular carcinoma has not been added to Rule H13 as well.

If a single tumor has metaplastic plus lobular carcinoma, Rule H13 does not apply and one has to continue through the rules. Unfortunately, the next rule registrars would be tempted to use is Rule H18: Code the histology that comprises greater than 50% of tumor when two histologies are on different rows in Table 3. This Rule does not state it does NOT apply to metaplastic carcinoma (only mucinous). So, if for some reason the lobular was greater than 50%, the incorrect histology would be coded (unless the registrar happened to remember Note 2 in the metaplastic carcinoma entry in Table 3).

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

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.

If the term discontinuous foci means separate tumors, then rule M14 would apply making these multiple reportable tumors.

The Hematopoietic and Lymphoid Neoplasms Database (Heme DB) definition for systemic mastocytosis with an associated hematological neoplasm (SM-AHN, 9741/3) states SM-AHN is a variant of systemic mastocytosis that arises with a myeloid disease of non-mast cell lineage (e.g., MDS, MPN, etc.) and that,

However, SINQ 20130172 conflicts with the Heme DB stating the systemic mastocytosis and the associated hematological neoplasm are a single primary coded to a single histology (9741/3) per Rule M2.

10/4/2018 Frozen Section Diagnosis: Brain tissue with atypical cells and inflammatory cells, defer to permanents for further evaluation. Note: Tissue for flow cytometry is submitted. Final Diagnosis: Preliminary Diagnosis: Brain Tumor, Biopsy: Neoplasm, suggestive of lymphoma (see comment). Comment: The tumor exhibits nuclear atypia and increased mitosis. The tumor cells are immunologically positive for LCA and with very high ki67 labeling index. GFAP and synaptophysin are not expressed by tumor cells. The above suggests a lympho-proliferative process. This case is forwarded to the hematopathology service of this department for further evaluation. The final diagnosis report will be issued by the hematopathologist as an addendum.

Supp Rpt Add Addendum Diagnosis: The brain biopsy showed brain tissue large lymphoid cell infiltrate. Additional immunohistochemical stains are performed. The large cells are positive for CD20, BCL2, BCL6 (subset), MUM1, and CD30, negative for CD3, CD5, and CD10. Staining for c-MYC is negative. Ki-67 positive large cells are approximately 18%. EBER is strongly positive by ISH. Diagnosis: Brain lesion, biopsy: EBV+ Diffuse Large B-cell Lymphoma. Addendum Comment: The concurrent flow cytometric study showed monoclonal lambda-positive B-cells without out CD5 and CD10 expression, consistent with B-cell lymphoma.

The 2021 ICD-O-3.2 Update includes papillary microcarcinoma (8341/3) as the preferred term for thyroid primaries (C739). However, there are multiple SINQ entries instructing registrars not to use code 8341/3 for diagnoses of micropapillary carcinoma of the thyroid (including SINQ 20071076, 20081127, 20110027, 20150023, and 20180008).

SINQ 20150023 specifically indicates: Per the WHO Tumors of Endocrine Organs, for thyroid primaries/cancer only, the term micropapillary does not refer to a specific histologic type. It means that the papillary portion of the tumor is minimal or occult (1 cm or less in diameter) and was found incidentally. WHO does not recognize the code 8341 and classifies papillary microcarcinoma of the thyroid as a variant of papillary thyroid carcinoma and codes histology to 8260. If the primary is thyroid and the pathology states papillary microcarcinoma or micropapillary carcinoma, code 8260 is correct.

Does this clarification apply to cases diagnosed 2021 and later? If WHO feels the term micropapillary still does not refer to a specific histologic type for the thyroid, why is 8341/3 listed as a preferred term for this morphology/site combination? For cases 2021 and later, should a diagnosis of Incidental papillary thyroid microcarcinoma (3 mm) in left lower pole, be coded as 8341/3 per the ICD-O-3.2, or as 8260/3 per clarification in multiple SINQ entries?

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