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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.

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)?

Per the 2018 Solid Tumor Rules instructions, Final Diagnosis and Staging Summary (synoptic report) have equal coding priority. However, it is unclear which takes priority, or if this should be a combination of components, when the histologies are two different specific histologic types per Table 3 of the Breast Solid Tumor Rules Manual.

CT a/p read by radiologist shows: "Bosniak 4 cystic lesion of right kidney." Follow-up MRI a month later reads "right kidney cystic lesion with enhancing mural nodule concerning for cystic renal cell carcinoma (RCC)." Urologist consult used the same wording of "Bosniak 4 cystic lesion" and "concerning for renal cell carcinoma." Treatment discussed but due to patient health status recommended repeat imaging. Repeat CT few months later reads: "cystic right renal lesion with enhancing nodule similar to most recent prior and suspicious for cystic RCC."

Though "suspicious for cystic RCC" per latest imaging is reportable, Bosniak 4 is "clearly malignancy, ~100% malignant" by definition, so is the case actually reportable with the first CT a/p date as date of diagnosis?

There is no specific ICD-O-3 code for a which resulted in abstractors assigning the malignant astrocytoma, NOS code. These lesions were previously called but we are seeing the new terminology more frequently.

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.

The bone marrow biopsy proved bone marrow with blasts comprising 15-19%. Neither the pathologist nor the physician specifically diagnosed this as AML, calling this only high risk disease or early evolving AML prior to starting the patient on Vidaza.

No further information can be obtained from the pathologist or the physician for this case. Should this early evolving AML be accessioned as an additional primary per Rule M10, or is this the same MDS that is now high risk as the blast count is up to 19%, but has not yet reached the threshold of 20% blasts usually required for AML per the Hematopoietic and Lymphoid Neoplasm Database?

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.