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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.

There are four invasive tumors in the right lung:

Large cell undifferentiated carcinoma in the right lower lobe (8012/3, C343);

Adenocarcinoma, acinar-predominant in the right lower lobe (8551/3, C343) that was 0.7 cm in size and limited to the lung;

Mucinous adenocarcinoma in the right upper lobe (8253/3, C341) that was 0.9 cm and limited to the lung;

Adenocarcinoma, NOS also in the right upper lobe (8140/3, C341) that was 1 cm and limited to the lung.

The Lung M Rules confirm the large cell undifferentiated carcinoma is a separate primary from the three adenocarcinoma tumors (Rule M8). The acinar adenocarcinoma and mucinous adenocarcinoma tumors are separate primaries (Rule M6). The adenocarcinoma, NOS tumor is the same primary as both the acinar and mucinous are adenocarcinomas (Rule M7).

How is Primary Site coded for both the acinar and mucinous adenocarcinomas if they represent multiple tumors reported as a single primary (when compared to the adenocarcinoma, NOS tumor)?

Should the adenocarcinoma, NOS tumor also be included when coding EOD Primary Tumor for both the right lower lobe acinar adenocarcinoma and right upper lobe mucinous adenocarcinoma primaries? Further follow-up with the physician is not possible.

Example: MRI found an intradural, extra-axial mass at T12/L1 with possible intramedullary component. Resection of the intradural intramedullary and extramedullary spinal cord tumor found a capillary hemangioma pathologically. The microscopic description on the path report describes a tumor with extensive vascularity involving the dura.

Should we equate the statement of capillary to mean the tumor is arising in a blood vessel as we do for venous hemangioma (non-reportable per SINQ 20130001)? Or should it be reportable as C700, 9131/0 because it is described as involving the dura (intradural, intramedullary and extramedullary)?

Example 1: 5/2013 diagnosis of HCC in segment 4B (single tumor), treated with microwave ablation in 7/2013. CT scan in 11/2017 with new 23mm hypodensity in liver segment 4 suspicious for recurrent disease. Clinical assessment in 1/2018: New enlarging lesion in liver most consistent with progression of HCC. Treated with RFA in 2/2018. Is the 2018 occurrence a new primary as imaging stated this was a new lesion?

Example 2: 7/2017 diagnosis of HCC in right liver; 2.5 cm lesion in segment 5/6 with a couple of satellites and 12mm lesion in segment 6, treated with Y90 radioembolization. Follow-up note in 11/2017: complete response of treated cluster of lesions in segment 5/6 and lesion in segment 6, increase in size of caudate lesion not amenable for treatment (this lesion was stated to be indeterminate on 7/2017 imaging). Caudate lesion finally stated as LI-RADS5 on 3/2018 imaging and was treated with chemoembolization 6/2018. 7/2018 and 10/2018 Follow-up imaging states LR-TR nonviable lesion in caudate lobe. 8/2019 CT shows caudate lobe with arterial enhancement, new compared to prior imaging, LR-TR viable. MD note states patient has small local HCC recurrence in segment 1 (caudate lobe) with plan to repeat TACE. Is this 8/2019 HCC a new primary as the patient was disease free for greater than 1 year, or is it the same tumor and a single primary?

In the April and July 2019 updates to the Solid Tumor Rules, the term simultaneous and Note 1 indicating histologies must be the same behavior were removed from rule M10 (ductal and lobular are a single primary).

We would like to confirm that rule M10 is the correct rule to apply to this case. This case is an invasive diagnosis approximately 4.5 years after an in situ diagnosis, so it seems like M17 should apply (invasive tumor following an in situ tumor more than 60 days later are multiple primaries).

An invasive tumor following an in situ tumor more than 60 days later of the same histology is a new primary. Similarly, it seems like an invasive tumor following an in situ tumor more than 60 days later of different histologies should be a new primary.

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.

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.

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.

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.