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Report Produced: 10/21/2025 19:01 PM

Report Question ID Question Discussion Answer Year
20091011 MP/H Rules/Histology--Breast: What histology is coded for a tumor diagnosed as "intraductal papillary carcinoma (neuroendocrine differentiation)"? See Discussion. Final diagnosis states: Right breast, excisional bx with findings most consistent with intraductal papillary carcinoma (neuroendocrine DCIS). The path micro states: the morphologic features are those of a neuroendrocrine-type tumor & IHC stains confirm neuroendocrine differentiation.

For cases diagnosed 2007 or later, assign code 8503/2 [Intraductal papillary carcinoma] using Breast rule H2. Code the histology from the final diagnosis.

There is no code for neuroendocrine DCIS in ICD-O-3.

 2009
20091010 MP/H Rules/Histology--Breast: What histology is coded when a final diagnosis on a lumpectomy specimen states "adenocarcinoma" but the regional lymph nodes show "poorly differentiated adenocarcinoma with signet ring differentiation"? See Discussion.

3/23 left breast mass bx: infiltrating lobular carcinoma.

6/22 left breast lumpectomy: infiltrating adenocarcinoma; sentinel lymph nodes with metastatic poorly differentiated adenocarcinoma with signet ring differentiation. Axillary resection with poorly differentiated metastasis in 8/9 nodes. The path micro states: tissue consists of sections of breast tissue having an infiltrating ca which in some areas infiltrates as small duct-like structures, and in other areas as small gland-like structures. In addition, there are foci in which the cells infiltrate in a single file fashion. In a few areas, cells having a signet ring appearance similar to those seen in the lymph nodes are encountered. In other areas, the signet ring appearance is not prominent. Areas of ductal or lobular ca in situ are not identified (the lymph node resection specimen shows 'signet ring appearance in some areas but no ductlike or tubular structures observed')

The comment on the lumpectomy path states: 'This is an unusual tumor in that it has histologic characteristics in varying areas, which would be consistent with infiltrating ductal carcinoma, infiltrating lobular carcinoma, tubular carcinoma or signet ring cell carcinoma. The metastatic material (8/9 total axillary lymph nodes) is most consistent with the poorly differentiated signet ring type portion of the tumor undergoing metastasis.'

For cases diagnosed 2007 or later:

Code the histology 8140 [Adenocarcinoma, NOS] using Breast rule H14.

Code the histology from the final diagnosis on the pathology report of the most representative specimen (the lumpectomy in this case). Do not code histology from the microscopic description. Code the histology from the primary site whenever available, not the metastatic site.

Comments on pathology reports can be used to code histology. However, in this case the final diagnosis is more definitive than the comments. The comment provides several choices and none of these appear in the final diagnosis; an indication that the pathologist was not able to clearly identify a more specific type in this case.

 2009
20140012 MP/H Rules/Histology--Breast: What is the correct histology code for this final diagnosis of a breast tumor: INVASIVE POORLY DIFFERENTIATED DUCTAL CARCINOMA WITH SQUAMOUS DIFFERENTIATION (METAPLASTIC FEATURES)?

Code the histology to 8575/3.

The instruction for coding duct and another non-duct histology not listed in Table 3 was inadverantly left out of the rules. The default is to code to the histology with the numerically higher ICD-O-3 code which is 8575/3.

 2014
20110004 MP/H Rules/Histology--Breast: Which MP/H rule applies when coding the histology field for a tumor described as a "metaplastic carcinoma, adenosquamous and spindle cell type"? See Discussion.

Per path comment: "The neoplasm is composed of adenosquamous carcinoma which merges with spindle cell carcinoma. The cystic component shows a mixed squamous and ductal epithelial lining which shows cytologic atypia and mitotic activity and can be seen to merge with invasive carcinoma. The features suggest the possibility that the tumor may have arisen from a sclerosing and cystic papilloma with squamous metaplasia, although a clearly benign component is not evident."

Would MP/H rule H19 apply based on the pathology report comment resulting in histology for the case being coded to 8255 [adenocarcinoma with mixed subtypes]? Or, would MP/H rule H14 apply based on the final diagnosis resulting in histology for the case being coded to 8575 [metaplastic carcinoma] because adenosquamous and spindle cell are not specific types of metaplastic carcinoma?

This is a metaplastic carcinoma as stated in the path diagnosis. Rule H14 applies. Assign code 8575/3. According to the WHO Classification, metaplastic carcinoma is a general term for a group of neoplasms characterized by a mixture of adenocarcinoma with dominant areas of spindle cell, squamous, and/or mesenchymal differentiation.

Use the Multiple Primary and Histology Coding Rules Manual for cases diagnosed 2007 or later to determine the histology for this case. Code histology to 8575/3 [metaplastic carcinoma] as stated in the pathology diagnosis.

Open the Multiple Primary and Histology Coding Rules manual. Choose one of the three formats (i.e., flowchart, matrix or text) under the Breast Histo rules determine histology for the case.

Go to the SINGLE TUMOR: INVASIVE CARCINOMA ONLY module. The rules are intended to be reviewed in consecutive order within the module from Rule H10 to Rule H19. You stop at the first rule that applies to the case you are processing.

Code the histology when only one histologic type is identified. According to the WHO Classification, metaplastic carcinoma is a general term for a group of neoplasms characterized by a mixture of adenocarcinoma with dominant areas of spindle cell, squamous, and/or mesenchymal differentiation.

2011
20071027 MP/H Rules/Histology--Breast: Which report and diagnosis should be used to code the histology if an excisional biopsy that removes the majority of the tumor has a diagnosis of "carcinoma," and the subsequent lumpectomy diagnosis is "microscopic residual disease consistent with infiltrating duct carcinoma"? For cases diagnosed 2007 or later, code histology for this case to 8010 [carcinoma]. The histology is coded from the pathology report with the most representative specimen (the most tumor tissue) even when the most representative specimen has a less specific histology. 2007
20110043 MP/H Rules/Histology--Breast: Which specimen should be used to code histology when a core biopsy revealed an unknown sized DCIS, comedo type and the partial mastectomy specimen showed only a 2mm focus of DCIS, solid pattern? See Discussion.

Should the histology be coded from the needle core biopsy or the partial mastectomy specimen? Patient had a needle core biopsy that revealed DCIS, comedo type, cribriform pattern, no tumor size given. Subsequently, the patient had a partial mastectomy which revealed DCIS, noncomedo type, solid pattern, largest focus of DCIS was 0.2cm.

Should the histology code be 8501/2 or 8230/2? The microscopic description on the partial mastectomy says that the previous core needle biopsy site revealed several foci of DCIS.

 Code the histology from the most representative specimen (the specimen with the MOST tumor tissue). Compare the size of tumor in the two specimens. If the tumor size is not available for both procedural specimens, code histology from the mastectomy specimen rather than the needle biopsy specimen. 2011
20081098 MP/H Rules/Histology--Colon: How do you use Rule H5 or H6 to code "moderately diff adenoca with mucinous component"?

For cases diagnosed 2007 or later, code the histology 8140 [Adenocarcinoma]. Rule H6 applies because the final diagnosis is not "mucinous adenocarcinoma" and the percentage of mucinous adenocarcinoma is not stated.

Rule H13 does not apply because "component" is not a term that indicates a specific histology.

2008
20120027 MP/H Rules/Histology--Colon: How is histology coded if a patient has two frank invasive adenocarcinomas in one segment of the colon and multiple tubular adenomas and hyperplastic polyps throughout the entire colon without a diagnosis of familial polyposis [FAP]? See Discussion.

Does Rule H19 apply which indicates the histology is coded to 8221 [adenocarcinoma in multiple adenomatous polyps] because there are multiple polyps (number not specified) throughout the colon? Does tumor have to arise in at least one of the adenomas in order to apply Rule H19?

Or, does Rule H22 apply which indicates the histology is coded to 8140 [adenocarcinoma, NOS] because the adenocarcinomas are both frank invasive adenocarcinomas and not adenocarcinoma arising in an adenoma?

Code the histology as adenocarcinoma, NOS [8140/3].

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

Open the Multiple Primary and Histology Coding Rules Manual. Choose one of the three formats (i.e., flowchart, matrix or text) and go to the Colon Histology rules to determine the histology code for this case. The Module you use depends on the behavior and number of tumors identified in the primary site.

Start at the MULTIPLE TUMORS ABSTRACTED AS A SINGLE PRIMARY Module Rule H15. The rules are intended to be reviewed in consecutive order from Rule H15 to Rule H24. Stop at the first rule that applies to the case you are processing. Code the histology when only one histologic type is identified. In this case, the only histology present was adenocarcinoma, NOS [8140/3].

Rules H17 through H21 do not apply in this case because there is no malignancy arising in any of the adenomas or polyps scattered throughout the colon.

2012
20071049 MP/H Rules/Histology--Colon: If a tubulovillous (TV) adenoma is in situ and other polyp(s) have an invasive component, does the in situ TV adenoma still have priority and should rule H18 be applied?

For cases diagnosed 2007 or later, always give precedence to coding the invasive. Rule H18 applies UNLESS the adenocarcinoma in the TV is in situ and the others are invasive. In this case, code the histology of the invasive adenocarcinoma.

This clarification will be added when the MP/H manual is revised.

 2007
20081085 MP/H Rules/Histology--Colon: Per MP/H rule H3 for colon, code 8144/3 [Adenocarcinoma, intestinal type] should not be used with C180-C189 [colon]. However, page 58 of the ICD-O-3 SEER Site/Histology Validation list of February 9, 2001 lists code 8144/3 as a valid histology for large intestine. See Discussion. None of the errata have this site/histo combination. It is causing problems with researchers because pathologists still use the term: Adenocarcinoma, intestinal type for tumors of the large bowel. Please clarify or print errata.

For cases diagnosed 2007 or later:

This issue has been presented to the Edits work group. The preliminary response is that 8144/3 will be removed from the valid site/histology list for large intestine, small intestine, and rectum.

The edits based on the site/type list are used by many organizations. Any change to the site/type list is taken to the Edits work group.

 2008