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Patient was diagnosed with lambda myeloma based on the M spike found on serum protein electrophoresis. A bone marrow biopsy was performed, but it was an insufficient sample.

SPEP is not listed in the Hematopoietic Database as a lab test that can be used as a definitive diagnostic method. Since the physician did base the diagnosis on the SPEP result, would it be appropriate to assign code 5 (Positive laboratory test/marker study) since there was no histological confirmation?

Under code 5, the Hematopoietic Manual states: Laboratory tests are listed under Definitive Diagnostic Methods in the Hematopoietic Database.

Neither the ICD-O-3.2 Implementation Guidelines nor the ICD-O-3.2 Coding Guidelines (including Tables 1-7) address reportability changes for chondrosarcoma grade 1. In the Solid Tumor Rules Manual, Head and Neck Equivalent Terms and Definitions, Table 7 (Tumors of Odontogenic and Maxillofacial Bone (Mandible, Maxilla)), Chrondrosarcoma grade 2/3 (9220/3) is included as a subtype/variant for sarcomas in these sites, but it does not address chrondrosarcoma, grade 1.

The ICD-O-3.2 Coding Table lists Chondrosarcoma, grade 1 as morphology code 9222/1. If Chondrosarcoma, grade 1 is no longer a reportable tumor for cases diagnosed 01/01/2021 and later, why wasn't this reportability change included in the ICD-O-3.2 Implementation Guidelines? If the standard setters chose not to include this reportability change, shouldn't Table 7 also indicate that all chondrosarcomas (NOS, grade 1, grade 2 or grade 3) are reportable for cases diagnosed 2018 and later?

How are registrars to make reportability and histology coding decisions for chondrosarcomas when neither source provides clear instructions regarding these tumors?

Patient has a history of B-cell lymphoma with multimodality treatment in 2002. Lab work in 2015 showed multilineage dysplasia leading to a diagnosis of therapy-related myelodysplastic syndrome. Patient presents in 2020 for a bone marrow biopsy now showing low-grade MDS. The MDS appears to have the same multilineage dysplasia previously identified.

MDS, NOS is not listed in the Heme DB as a possible transformation of t-MDS, nor is it listed as a Same Primary for t-MDS. Likewise, t-MDS is not listed as a more specific myelodysplastic syndrome, a transformation of MDS NOS, or a Same Primary as MDS, NOS.

The first M rule that applies to this case is M15, and the Multiple Primaries Calculator indicates that the MDS, NOS should be a new primary.

Patient was diagnosed with invasive ductal carcinoma with mucinous features in February 2021, left breast biopsies at 2:00 (3 cm from nipple) and 3:00 (8 cm from nipple) positions. Intraductal component was absent in those specimens.

Subsequent left breast total mastectomy in March 2021, provided a final diagnosis of multifocal mixed mucinous carcinoma, grade 1, 27 and 8 mm and ductal carcinoma in situ (DCIS), low to intermediate grade, with focal mucinous features. The Staging Summary lists Histologic Type as mixed mucinous carcinomafor both foci of invasive carcinoma. DCIS is also noted as present negative for extensive intraductal component.

There does not appear to be a clear instruction or code for this histology. As a central registry, we are unable to follow-up with the pathologist regarding this diagnosis.

Just to be clear, there are 2 foci of invasive mixed mucinous carcinoma in this case measuring 27 mm and 8 mm. The DCIS component measured 56 mm.

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.

A patient had posterior cervical lymphadenopathy status post biopsy and subsequent lymph node dissection showed metastatic melanoma in 2018. Workup showed no skin lesions or primary site. Final diagnosis is melanoma of unknown primary (unknown if cutaneous or non-cutaneous). Should C760 be used as the primary site for this case since the histology codes of 8700-8790 are included in the Cervical Lymph Nodes and Unknown Primary Tumors of the Head and Neck schema in SEER*RSA?

We think this should be a single primary because the Solid Tumor rules do not apply to metastases. However, we are not sure whether or not the instructions outlined for prostate (SINQ 20180088, 20130221), that indicate we are to accession a new metastatic tumor only with a small cell neuroendocrine histology after an adenocarcinoma, also applies to lung primaries.

We are aware of a phenomenon in which lung adenocarcinoma cases treated with Erlotinib can transform to small cell, but do not know whether it impacts the number of reportable primaries.

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?

The ICD-O-3.2 Coding Table includes Mullerian mixed tumor as the preferred term for histology code 8950 (previously malignant mixed Mullerian tumor/MMMT). This table also includes carcinosarcoma, NOS as the preferred term for histology code 8980. Neither the ICD-O-3.2 Coding Table nor the Implementation Guidelines address the long-standing issue of coding histology for diagnoses of carcinosarcoma/malignant mixed Mullerian tumor.

These endometrial primaries are frequently diagnosed as both carcinosarcoma and MMMT. The questions regarding histology coding for carcinosarcoma and carcinosarcoma/MMMT of the endometrium date back to before the Multiple Primaries/Histology Rules, with at least three SINQ entries instructing registrars not to use code 8950/3 (MMMT) for diagnoses of MMMT. SINQ has instructed registrars that MMMT is a synonym for carcinosarcoma and these tumors should be coded to 8980 (carcinosarcoma), not to 8950 (MMMT). The most recent SINQ is partly inconsistent with the others, indicating 8950 can be used if the tumor is only described as MMMT. The other SINQ entries state carcinosarcoma should be used as it is the preferred term for MMMT. (See SINQ 20061008, 20100009, 20180071.)

The most recent SINQ (20180071) specifically indicates: According to the WHO Classification of Tumors of Female Reproductive Organs, 4th edition, MMMT (8950/3) is now a synonym for carcinosarcoma (8980/3) even though it has a separate ICD-O code. The ICD-O code for MMMT is no longer in the WHO book. However, MMMT is in the ICD-O-3.2 Coding Table and is not stated to be obsolete or a synonym. Which is correct, the clarification in the SINQ or the 2021 ICD-O-3.2 Coding Table?

For a 2021 diagnosis of carcinosarcoma/malignant mixed Mullerian tumor, how should registrars code the histology? Follow the previous SINQ entries and Rule H17 to code the histology to 8980 when the diagnosis includes both carcinosarcoma and MMMT? Do these previous SINQ entries still apply to cases diagnosed 2021 and later?

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