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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.

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?

In the 2018 ICD-O-3 Update Table, undifferentiated high-grade pleomorphic sarcoma and undifferentiated high-grade pleomorphic sarcoma of bone (C40_) were both listed as a New Term for histology 8830/3. There was no site restriction for a diagnosis of undifferentiated high-grade pleomorphic sarcoma. Therefore, it appears the diagnosis could easily be applied to a soft tissue tumor. This histology is used by pathologists in our region for soft tissue tumors as well as bone tumors. However, in the ICD-O-3.2 Table an entry (or synonym) was not provided for a tumor outside the bone.

The ICD-O-3.2 Table only lists undifferentiated high-grade pleomorphic sarcoma of bone for site codes C40_ and C41_ as a synonym for histology 8830/3. This also is not listed in the ICD-O-3.2 Implementation Guidelines. As a result, it is unclear whether a diagnosis of undifferentiated high-grade pleomorphic sarcoma of the soft tissue can be coded to 8830/3 and/or can be a synonym for the preferred term (8830/3, Malignant fibrous histiocytoma). Can a diagnosis of undifferentiated high-grade pleomorphic sarcoma of the soft tissue be coded to 8830/3, C49_ as it was per the 2018 ICD-O-3 Update Table?

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

Path report reads: 7/15/2019 A. Endometrium, curettings: Serous carcinoma, high grade. B. Endometrial polyp, curettings: Serous carcinoma, high grade.

If coded to 8461/3, according to AJCC, this would not be an ideal code (since it is outdated). Also, endometrium is not included in the suggested site codes for 8461/3 according to the 8/22/2018 ICD-O-3 update.

A physician stated the patient likely had secondary polycythemia vera due to cardiac and pulmonary conditions but that a polycythemia vera could not be ruled out. A JAK2 was ordered that was positive for JAK2 V617F mutation. The patient was treated with hydrea.

According to SEER SINQ 20120049, secondary polycythemia vera is not reportable. However, in this case, the patient was positive for JAK2 V617F mutation. Therefore, is this reportable? We looked for guidance in the Hematopoietic and Lymphoid Neoplasms Database and found it confusing that secondary polycythemia vera was not mentioned or discussed under polycythemia vera in the database. The only thing we could find was secondary polycythemia NOS that was discussed under polycythemia.

Final Pathologic Diagnosis:

Vulvar cyst, excision: Focal mammary-type ductal carcinoma in situ, intermediate grade, arising within cystically dilated duct (See Comment)

Size of DCIS: 0.7 CM.

Margins: Negative.

Comment

Sections demonstrate a cystically dilated duct. Focally, at the periphery of the duct, there is a neoplastic monomorphic proliferation of ductal cells with intermediate grade nuclei. No associated necrosis is identified. Immunostains for GATA-3 and estrogen receptor are strongly positive within the neoplastic cells, supporting origin from mammary-like epithelium. Immunostain for p63 demonstrates preservation of a basal layer around the dilated duct, including the region involved by DCIS. Immunostain for cytokeratin 5/6 shows loss of expression within the DCIS. No stromal invasion is identified. The cyst appears to be completely excised.

12/01/2020 post op visit with surgeon:

Ductal carcinoma in situ (DCIS) of the left vulva in an excised cystic lesion.

PLAN: I reviewed the pathologic findings from the excision of the left vulvar cyst. This appears to be a cystic lesion in the mammary line with focal DCIS. It was excised completely with negative margins. It would not warrant any additional treatment except expectant management.

SEER*RSA states EOD Primary Tumor should be coded to 800 for an incidental finding of prostate cancer on prostatectomy for other reasons.

The SEER Manual states to assign code 000 for Tumor Size--Clinical when EOD Primary Tumor is coded to 800; however, the definition for Tumor Size--Clinical indicates clinical classification is composed only of diagnostic workup prior to treatment.

If there is no clinical workup for an incidental finding of prostate cancer, code 000 does not seem appropriate (does not meet criteria for clinical classification). Code 999 seems more appropriate for incidental findings during surgery for other reasons. The SEER Manual does not provide this exception in the current instruction.

We are confused by SINQs 20180097, 20150001, and 20140051.  The latter two indicate that “well-differentiated neuroendocrine neoplasms” of the duodenum and appendix are reportable because they’re synonymous with neuroendocrine tumor (NET).  Yet 20180097 states “primary hepatic neuroendocrine neoplasm” is NOT reportable unless there is documentation that it’s being used as a synonym for Primary Hepatic Neuroendocrine Tumor (PHNET).  In addition, we see in the 2021 ICDO-3.2 update that only “poorly differentiated neuroendocrine neoplasm” is listed with behavior code /3 and noted to be reportable for 2021+ on the companion annotated histology list.  Does reportability of neuroendocrine neoplasms depend on primary site, differentiation terminology within the histology name, or something else?  Our casefinding staff is hoping for a general reportability guideline to follow when they come across “neuroendocrine neoplasms” NOS.  For example, we have a 2020 pathology report for a core biopsy of a soft tissue pelvic mass with final diagnosis of low grade neuroendocrine neoplasm; there is no further clarification as to whether it is felt to be primary or metastatic, and we have no other associated records for this patient in our central registry.