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Example: Patient has a secretory carcinoma of minor salivary gland tissue (mammary analogue secretory carcinoma [MASC]) of the mucosal lower lip; it is unclear which table to use and how to arrive at the correct histology using the H Rules.

Rule H1 (code the histology when only one histology is present) states, Note 1: Use Tables 1-9 to code histology. There is no table that includes the lip. The correct histology should be 8502 which is listed in Table 6 (Tumors of Salivary Glands) however this does not correspond to minor salivary glands of the mucosal lip (site C003 per ICD-O-3 coding instruction).

The 2018 ICD-O-3 Update table does not include this histology, however Table 6 indicates code 8502 (secretory carcinoma) is a new code that was approved by IARC/WHO.

The ICD-O-3 only includes this histology as secretory carcinoma of breast. Therefore, in order to arrive at the correct histology, one must be aware of previous SINQ entries 20160036 and 20130003 that indicate secretory carcinoma (or MASC) is histology 8502. However, these are related to MP/H Rules, so registrars may be hesitant to apply this guideline to cases coded using Solid Tumor Rules.

Cytology is not listed in the Priority Order for Using Documentation to Identify Histology (Histology Coding Rules) in the Head and Neck schema. Other schemas do include cytology in the hierarchy below tissue from a biopsy or resection. Cytology is often less specific than histology, so one would expect cytology to be listed below tissue in this hierarchy. Was this an oversight? Or would cytology be equivalent to histology if it provided the most specific histology for the case?

Should histology be coded as paraganglioma, NOS (8680/3) or as extra-adrenal paraganglioma, NOS (8693/3) for a diagnosis of paraganglioma in the bladder? Does the pathologist have to specifically diagnose the tumor as extra-adrenal paraganglioma, NOS to use histology code 8693/3? Or, does any diagnosis of paraganglioma (NOS) arising outside of the adrenal gland, carotid body, middle ear, or aortic body (the specified sites for other types of paragangliomas) qualify as an extra-adrenal paraganglioma, NOS?

The ICD-O-3.2 Implementation Guidelines (Tables 6 and 7) provide an associated site of C755 for histology 8680/3 (paraganglioma, NOS), but no associated site code is provided for histology 8693/3 (extra-adrenal paraganglioma, NOS). If the preferred site for paraganglioma, NOS is the paraganglia, would a paraganglioma in the bladder be an extra-adrenal paraganglioma?

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

Table 1 of the 2018 Kidney Solid Tumor Rules (STR) lists succinate dehydrogenase-deficient renal cell carcinoma as histology code 8312, but in the ICD-O-3.2 Coding Table it is listed as histology code 8311.

No changes were made in the Kidney STR. As a result, the histology change described in the ICD-O-3.2 Coding Table conflicts with Table 1. Succinate dehydrogenase-deficient renal cell carcinoma (SDHD) is listed in Table 1 as a synonym for renal cell carcinoma, NOS (8312). However, the ICD-O-3.2 Coding Table lists this as a related term for histology code 8311/3. This related term was not discussed in the Implementation Guidelines, and no change was noted in the STR.

While it seems we should continue to follow the STR, without clarification as to why this histology change was not implemented in STR, achieving consistency will be problematic if registrars jump straight to the ICD-O-3.2 Coding Table to code histology for cases diagnosed 2021 and later. If this code cannot be used for cases diagnosed prior to 2021, should that clarification be included in the STR?

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

Example: Diagnosis is made on liver core biopsy path showing Metastatic carcinoma, poorly-differentiated, consistent with lung primary. Diagnosis Comment notes: Carcinoma cells are positive for CK7 and TTF-1, negative for CK20.

Subsequent immunohistochemistry report for PD-L1 testing states Liver: Metastatic adenocarcinoma consistent with lung primary. Interpretation: no PD-L1 expression.

IHC/Biomarker testing is often performed to determine treatment type, but it seems like some of the biomarkers for treatment planning are also histology specific. The Solid Tumor Rules do not address the use of biomarkers reports in the histology coding instructions.

Examples

Example #1: CAP histology type: Adenocarcinoma, solid predominant, Final diagnosis states that Adenocarcinoma, poorly differentiated, solid predominant (80%) and cribriform (20%) subtype (see lung carcinoma synoptic report)

Example #2: CAP histology type : Invasive adenocarcinoma, solid predominant, Other Subtypes Present (specify subtype(s), may also include percentages): acinar (45%) and micropapillary (5%) Final diagnosis : adenocarcinoma of the lung, please see Synoptic Report

Example #3: CAP histology type: Adenocarcinoma, acinar predominant , Adenocarcinoma, solid predominant Final diagnosis: Adenocarcinoma, poorly differentiated, solid predominant (60%), papillary (30%) and acinar (10%) subtype (see lung carcinoma synoptic report)

Regarding the answer to SINQ 20180093: This is a single primary; coded 8140/3 adenocarcinoma. In the biopsy and the two tumors found on lobectomy, the specific adenocarcinoma histologies are described as acinar predominant pattern, solid growth pattern and lepidic predominant pattern. You do not code a pattern, so rule M7 above applies and this is a single primary.

My question is based on Note 2 in Coding Multiple Histologies for lung cancers that says: Predominantly describes the greater amount of tumor. Predominant and majority are synonyms. Per the CAP protocol, the term predominant is acceptable for the following specific subtypes of adenocarcinoma. For these subtypes only, the word predominant is used to describe both the subtype and the grade of the tumor.

For example, pathologic diagnosis is non-small cell carcinoma with squamous features. The medical oncologist describes this as squamous cell carcinoma and begins treatment regimen. As I interpret the rules, we would use code 8046, non-small cell carcinoma, because of instruction 2 and the fact that features is not included in the list of ambiguous terminology.