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Pituitary blastoma was not added to Table 3 (Specific Histologies, NOS, and Subtypes/Variants) of the 2018 Malignant CNS and Peripheral Nerves Solid Tumor Rules as part of the December 2020 update. This is a new malignant CNS histology for 2021 and later. Not including this histology in Table 3 results in the registrars being required to check another source to correctly code this histology. If this histology cannot be used for cases diagnosed prior to 2021, should that diagnosis year 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: Posterior fossa tumor resection final diagnosis was medulloblastoma, WHO Grade IV. The diagnosis comment notes the current tumor resection reveals large irregular reticulin-free nodules with streams of neoplastic cells in a fibrillary background in association with narrow reticulin-rich internodular strands of poorly differentiated neoplastic cells. Taken together, these findings are indicative of medulloblastoma with extensive nodularity. The diagnosis comment provided only one histology.

Per the 2018 Solid Tumor Manual, Malignant CNS, Priority Order for Using Documentation to Identify Histology instructions, an addendum or comment has priority over the final diagnosis. Although indicative is not listed on any ambiguous terminology list, is this an ambiguous diagnosis that must be ignored? Or does the diagnosis comment in this case provide a single, specific diagnosis of medulloblastoma with extensive nodularity?

Patient has a resection labeled as: Spine, designated intramedullary lesion. The Final Diagnosis is: Melanocytic neoplasm with features most consistent with primary intramedullary melanocytoma. The Diagnosis Comment states: The overall immunophenotypic and morphologic impression is a primary central nervous system melanocytoma.

The ICD-O-3 lists melanocytoma, NOS histology code as 8726/0, but does not provide a site-associated code. If the ICD-O-3 is used, the histology would be 8726/0 and the primary site presumably would be C720 since the tumor was specifically described as being intramedullary (i.e., within the spinal cord medulla).

Table 6 (Solid Tumor Rules, Non-Malignant CNS Equivalent Terms and Definitions) does not list either an intramedullary melanocytoma or melanocytoma (NOS). However, Table 6 does include meningeal melanocytosis 8728/0 and meningeal melanocytoma 8728/1. If Table 6 is used and the histology is coded 8728/1, then the primary site would presumably be C701 per the ICD-O-3 site-associated listing for this histology (C709).

Instruction number 1 under the Coding Multiple Histologies instructions states to code histology when the histology is described as subtype, type or variant. The general rules do indicate we can code the histology identified as type, but when applying the H Rules, it seems an argument could be made for either H1 or H3. H1 applies if you ignore the diagnosis of carcinoma and only code the histologic type: urothelial carcinoma. However, the rules do seem to imply that you take all histologies into account (e.g., code the subtype/variant when there is a not otherwise specified (NOS) and single subtype/variant). Following this logic, Rule H3 seems to be the only rule that fits, and one would code the subtype/variant urothelial carcinoma when the diagnosis is carcinoma NOS, histologic type: urothelial carcinoma.

The problem is that urothelial carcinoma is not a subtype/variant of carcinoma (NOS) per Table 2. The entry for Carcinoma NOS in Table 2 states, Subtypes of carcinoma NOS include adenocarcinoma and all subtypes/variants of adenocarcinoma. To some, urothelial carcinoma is a more specific type of carcinoma; however, urothelial carcinoma is not also listed as a subtype of carcinoma or of adenocarcinoma; only adenocarcinoma is categorized as a subtype of carcinoma. Consistently applying the rules becomes an issue when rules are interpreted in different ways. Should this Table be amended to include urothelial carcinoma as a subtype/variant of carcinoma NOS with the same caveat given to adenocarcinoma in Table 2?

The note in the Urinary Terms and Definition states, Both Ta and Tis tumors are technically noninvasive. Code the histology specified by the pathologist. While it is true that both Ta and Tis are technically noninvasive, the AJCC defines Ta specifically for, A pathologist's use of Ta does indicate the noninvasive carcinoma did arise from a papillary tumor. However, not all pathologists use terminology that, following the Urinary Solid Tumor Histology Coding Rules, will result in a histology coded to 8130, despite an AJCC-defined Ta (noninvasive papillary carcinoma) tumor having been diagnosed because the tumor projected from the wall on a stalk.

In our region a number of pathologists provide the following types of diagnosis.

Histologic type: Noninvasive.

Histologic grade (WHO/ISUP 2016): High-grade.

Tumor configuration: Papillary.

The pathologist and/or physician may then stage this as Ta. How is the histology coded for these cases if the H Rules do not allow one to code the papillary and noninvasive Ta disease as not equivalent to noninvasive papillary carcinoma?

Flat (in situ) urothelial carcinoma has an increased risk of invasive disease compared to the noninvasive papillary urothelial carcinomas. Will there be inconsistencies or a resulting impact to analysis of truly flat/in situ urothelial carcinoma vs. papillary urothelial carcinomas if the papillary tumors are not being coded as such?

12-19-19 Transurethral resection of bladder tumor pathology revealed high-grade papillary urothelial carcinoma with focal glandular and neuroendocrine features; Pathology Overread: High-grade papillary urothelial carcinoma with focal glandular and neuroendocrine differentiation. Carcinoma invades muscularis propria pT2.

Histology 8130

01/20/20 to 07/01/20, completed 6 cycles of gemcitabine/cisplatin.

07/30/20 Robotic radical cystoprostatectomy with bilateral pelvic lymph node dissection, open ileal conduit pathology revealed carcinosarcoma, invading perivesical fat, no lymphovascular invasion, negative margins. ypT3bN0M0 disease; Pathology Overread: Carcinosarcoma arising in association with high-grade papillary urothelial carcinoma.

Histology 8980/3 or is there another histology that should be used?

Similar to an issue previously submitted SINQ 20180063, Table 1 (WHO Grades of Select CNS Neoplasms) in the Non-Malignant CNS Equivalent Terms and Definitions section states WHO Grade I tumors are always non-malignant. However, this does not mean that the tumors listed in Table 1 as WHO Grade I are always benign (/0). Some tumors listed with a WHO Grade I have a behavior of /1 (borderline) per the ICD-O-3 and/or Tables 5 and 6. The Behavior coding instructions do not currently indicate these are the appropriate sources to use when the pathologist and/or physician do not comment on the behavior of these tumors. In our area, pathologists do not explicitly state the behavior for these tumors; the pathologist only assigns the WHO Grade.

The patient was incidentally diagnosed with cancer on a prophylactic mastectomy, so there are no positive imaging findings to correlate the number of tumors/masses. The final diagnosis was invasive tubular carcinoma, and referred to the CAP Protocol. The CAP notes: However, it does not specify whether the single contiguous focus also includes the in situ component. The CAP goes on to note DCIS was present: The gross description does not provide any indication of either a single or multiple tumors/masses/lesions, though it was referred to as "Lesion 1" in the gross description with no indication of other lesions.

The format of the CAP Protocol frequently does not specify whether the DCIS is a separate measured tumor, or if it is a component of the invasive tumor. This makes it difficult to determine whether the DCIS should be a separate primary when the invasive tumor is not also a type of ductal carcinoma. Per both the 2007 MP/H and 2018 Solid Tumor Rules, an invasive tubular carcinoma and a ductal carcinoma in situ would be multiple primaries if they were multiple tumors. Should we default to Rule M1: Abstract a single primary when it is not possible to determine if there is a single or multiple tumors? Or should we assume these are separate tumors because they were both sized, the focality only described a single invasive tumor, and the tumors are not both ductal carcinomas?

Since AIN I is not reportable and AIN II is not reportable until 2021, we are not sure if we can say the patient was disease free because there was no intervening reportable tumor (AIN III), or was never disease free because there was evidence of related disease (lower grade dysplasia).

The patient was diagnosed with a left testis primary in the early 1980s that did not include a seminoma component per the information available. The slides were not available for review. In 2024, the patient was found to have a metastatic seminoma involving multiple pelvic lymph nodes and the prostate. The right testicular ultrasound was negative. The managing physician noted this was both a "relapsed seminoma" and a "Stage IIC seminoma."

Should the new diagnosis of metastatic seminoma be accessioned as a new primary based on the histology differences? Or is this situation similar to SINQ 20160073 in which this is a single primary even though the metastases are a distinctly different histology?