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Report Produced: 10/08/2026 18:02 PM

Report Question ID Question Discussion Answer Cancer Site Category Data Item Category Year
20020015 Histology (Pre-2001): For cases diagnosed before 1/1/01, what code is used to represent the histology "small cell neuroendocrine carcinoma"? For tumors diagnosed prior to 2001, code the Histology field to 8041/3 [small cell carcinoma] for "small cell neuroendocrine carcinoma". N/A Histology 2002
20210009

Solid Tumor Rules (2018, 2021)/Histology--Melanoma: In what situation will Rule H4 be used to code the histology to regressing melanoma? See Discussion.

Rule H4 states: Code 8723/3 (malignant melanoma, regressing) when the diagnosis is regressing melanoma. However, if the diagnosis was strictly regressing melanoma or malignant melanoma, regressing, the first rule that applies is Rule H1 because regressing melanoma is a single, specific histologic type and Rule H1 states: Code the histology when only one histologic type is identified. Following the current rules, one would never arrive at Rule H4. Should the H Rules be reordered? Or should an example of when one would use Rule H4 be added to clarify when to use this rule?

Coding regressing melanoma has been an issue as registrars may not realize it is a reportable histology. Hence, H4 was written to reinforce correct histology. A note will be added to H1 instructing registrars to continue thru rules when the diagnosis is regressing melanoma.

 Melanoma Histology 2021
20200056

Reportability/Histology--Gallbladder: Is Intracholecystic papillary neoplasm (ICPN) with low-grade intraepithelial neoplasia reportable? The primary site is gallbladder.

Intracholecystic papillary neoplasm (ICPN) with low-grade intraepithelial neoplasia is not reportable. The WHO assigns a behavior of 0 to these neoplasms.

 Gallbladder Histology 2020
20180006

MP/H Rules/Histology--Breast: Should encapsulated papillary carcinoma of the breast with a separate focus of ductal carcinoma in situ be coded as 8050/2 (papillary carcinoma) and staged as in situ? See Discussion.

Pathology--Right breast, lumpectomy with needle localization: Encapsulated papillary carcinoma of the breast. A separate focus of ductal carcinoma in situ is present. Sentinel lymph node, right breast, biopsy: One lymph node, negative for malignancy. No metastatic carcinoma is seen on slides stained with immunostain for cytokeratin (AE1/AE3). Specimen laterality: Right. Tumor size: 1.2 cm. Histologic type: Encapsulated papillary carcinoma. Nuclear grade: Grade 1 (low). Mitotic rate: Score 1. Ductal carcinoma in situ (DCIS): DCIS is present. Estimated size (extent) of DCIS: 3 mm. Architectural patterns: Cribriform and papillary. Nuclear grade: grade 1 (low). Necrosis: Not identified. Margins: Margins uninvolved by encapsulated papillary carcinoma. Distance from closest margin: 8 mm, superior Margins uninvolved by DCIS. Distance from closest margin: 11 mm, superior Lymph nodes: Total number of lymph nodes examined (sentinel and nonsentinel): 1. Number of sentinel lymph nodes examined: 1. Number of lymph nodes with tumor cells: 0. Pathologic staging: Primary tumor: See comment. Regional lymph nodes: pN0(i-). Comment: In the WHO Classification of Tumours of the Breast (2012), it is stated that "there is no universal agreement on how to stage encapsulated papillary carcinomas. In the absence of conventional invasive carcinoma, the consensus of the WHO Working Group was that such lesions should be staged and managed as Tis disease."

For cases diagnosed prior to 2018

Code as encapsulated papillary carcinoma, 8504/3; this is a synonym for intracystic carcinoma (WHO Classification of Tumors of the Breast). Stage this case as invasive.

 Breast Histology 2018
20100002 Reportability/Histology--Colon: Is a colon tumor reportable if the pathology report final diagnosis is high grade dysplasia but CAP protocol histologic type designation is adenocarcinoma in situ? See Discussion. The microscopic description and the final diagnosis on the pathology report indicate the tumor is a large tubulovillous adenoma of the cecum with focal surface high grade dysplasia. The CAP protocol histologic type designation is adenocarcinoma in situ and pT designation is pTis. Which has priority? Is the case reportable?

The case is reportable because carcinoma in situ is stated. Carcinoma in situ has higher priority than severe dysplasia or high grade dysplasia.

Per AJCC 6th edition colon chapter, the terms "high grade dysplasia" or "severe dysplasia" may be synonymous with carcinoma in situ. Because the pathologist gave carcinoma in situ information within the CAP, (s)he is apparently defining the dysplasia as in situ carcinoma.

 Colon Histology 2010
20220006

Histology/Brain and CNS:  How is histology coded for a 2021 diagnosis of “neuroepithelial tumor with PATZ1-EWSR1 fusion, not elsewhere classified” found during a right thalamic mass resection? See Discussion.

Patient has a remote history of a right thalamic mass status-post two resections; reported as malignant oligodendroglioma (pathology not received) and chemo/radiation therapy, who recently presented with persistent headaches. Imaging revealed a 3.4 cm heterogeneous lobulated right thalamic mass with coarse calcifications and a probable cystic component.

Pathologist indicates the histologic and immunophenotypic features of this neoplasm are that of relatively circumscribed neuroepithelial tumor without high grade features (mitotic activity, microvascular proliferation, necrosis). Molecularly this neoplasm is characterized by a PATZ1-EWSR1 fusion, which has recently been proposed to be a distinct neuroepithelial tumor entity with a broad histological spectrum.

Assign 8000/1. Neuroepithelial tumor with PATZ1-EWSR1 fusion, not elsewhere classified, is not recognized as a distinct entity at this time. It is not listed in ICD-O-3.2 or in the 5th edition of the WHO CNS classification.

 Brain and CNS Histology 2022
20110024 MP/H Rules/Histology--Breast: How is histology coded, and which MP/H rule applies for a diagnosis of ductal carcinoma in situ with clear cell features? See Discussion.

None of the histology rules for in situ breast seem to apply to this case:

  • Rule H3 doesn't seem to apply because "clear cell" is not a specific intraductal carcinoma.

  • Rule H6 doesn't seem to apply because there is not a combination of intraductal and 2 or more specific types of intraductal.

  • Rule H8 wouldn't apply because one of the types is intraductal.

    • For cases diagnosed 2007 or later:

    Code 8523/2 [intraductal carcinoma mixed with other types of in situ carcinoma]. Rule H6 should apply to this case.

    The wording in the Rule H6 needs to be clarified to handle a case of intraductal carcinoma with one or more subtypes that are not ductal. This will also require a modification to Table 3. A row needs to be added to the table labeled, "Intraductal and one or more of the histologies in Column 2." The Column 3 text for the newly added row would read, " Intraductal mixed with other types of carcinoma." The appropriate histology code to be reported per Column 4 would be 8523/2. This will be done in the next revision of the rules.

    		Breast Histology 2011
    		20120018 MP/H Rules/Histology--Breast: How is histology coded if a lumpectomy reveals multifocal ductal carcinoma in situ spanning an area of 0.9-1.2 cm with close margins and a subsequent mastectomy reveals only a single focus of lobular carcinoma in situ measuring 0.2 cm in the UOQ, remote from all surgical margins? See Discussion. Does the general instruction apply in this case that indicates the histology is coded from the most representative tumor specimen resulting in the histology coded to 8500/2 [DCIS]? Or is the histology coded to 8522/2 [duct and lobular carcinoma in situ] per Rule H28 because there is any combination of lobular [8520] and duct carcinoma [8500]?

    Code the histology to duct and lobular carcinoma in situ [8522/2].

    For cases diagnosed 2007 and later, the steps used to arrive at this decision are:

    Go to the Breast MP rules found in the Multiple Primary and Histology Coding Rules Manual. Start at the MULTIPLE TUMORS Module Rule M4 because the patient had multiple foci of DCIS and a separate, single focus of LCIS. The rules are intended to be reviewed in consecutive order within the applicable Module. Tumors that are lobular and duct are a single primary.

    Go to the Breast Histology rules found in the Multiple Primary and Histology Coding Rules Manual. Start at the MULTIPLE TUMORS ABSTRACTED AS A SINGLE PRIMARY Module Rule H20 because the patient has multiple foci of DCIS and LCIS. Code the histology as 8522/2 [duct and lobular carcinoma in situ] when there is any combination of lobular [8520] and duct carcinoma.

    The DCIS and LCIS are separate tumors. The DCIS was removed by the lumpectomy and the LCIS by the mastectomy. The most representative specimen for the DCIS is the lumpectomy. The most representative specimen for the LCIS is the mastectomy. Both pathology reports must be used in this case to determine the histology.

    		Breast Histology 2012
    		20150036

    Reportability/MP/H--Kidney: "Multilocular clear cell renal cell carcinoma." Would this be coded 8310? See discussion.

    Multilocular clear cell renal cell carcinoma is a specifc histologic type listed in the CAP cancer protocol for kidney, but not in the ICD-O-3 and it is not on the list of specific types of renal cell carcinomas in Table 1 of the kidney equivalent terms and definitions in the MP/H manual. There is a malignant multilocular cystic nephroma 8959 in Table 1, but I can't tell if this the same histology as what is stated in this path report.

    Apply Kidney rule H5 and code the clear cell (8310/3) which is the specific type of renal cell. Multilocular is a variant of clear cell which is a variant of renal cell carcinoma. As of yet, no new ICD-O morphology code as been proposed for this specific histology. It will be addressed in the revised rules.

    		Kidney, renal pelvis Histology 2015
    		20091003 MP/H Rules/Histology--Peritoneal primary: Can the cell types from the primary site and a metastatic site be combined to code histology? See Discussion. Patient has vaginal mass biopsy diagnosed as 'papillary carcinoma with psammoma bodies.' Two weeks later the patient has laparoscopy with multiple peritoneal biopsies, diagnosed as 'well differentiated serous adenocarcinoma'. Patient stated to have peritoneal primary with mets to vagina and was treated with chemotherapy. Do we code the histology to 8441/31 from the primary site biopsies, or can we use 8460/3, combining the cell types from the primary and metastatic sites? Please see SINQ 20041062 for a similar question before the 2007 MP/H rules.

    For cases diagnosed 2007 or later, assign code 8441 [serous adenocarcinoma, NOS].

    Code the histology from the primary site when available. Do not combine histologies from primary and metastatic sites.

    In this primary peritoneal case, the diagnosis from the peritoneal biopsies was serous adenocarcinoma.

    		 N/A Histology 2009