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Report Produced: 05/25/2026 03:12 AM

Report Question ID Question Discussion Answer Year
20020012 MP/H Rules/Histology--Breast: What code is used to represent the histology "ductal carcinoma in situ and invasive lobular carcinoma"? See discussion. Is the histology coded to the combination code of 8522/3 (ductal and lobular) or to the invasive component 8520/3 (lobular)?

For cases diagnosed 2007 or later:

Assuming ductal carcinoma in situ and invasive lobular carcinoma are present in a single tumor, code 8520/3 [Infiltrating lobular carcinoma, NOS].

Using the 2007 MP/H rules for breast, the single tumor invasive and in situ carcinoma module, start and stop at rule H9 and code the invasive histology.

 2002
20120051 MP/H Rules/Histology--Breast: What histology code for a diagnosis of pleomorphic lobular carcinoma in situ?

For cases diagnosed 2007 or later, code the histology as lobular carcinoma, in situ [8520/2].

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). Go to the Breast Histo rules because site specific rules exist for this primary.

Start at the SINGLE TUMOR: IN SITU CARCINOMA ONLY module, Rule H1. The rules are intended to be reviewed in consecutive order. Stop at the first rule that applies to the case you are processing. Code the histology to lobular carcinoma in situ [8520/2] because this is the only histologic type identified.

Pleomorphic lobular carcinoma is a variant of lobular carcinoma which does not have an ICD-O-3 code. It is still a lobular carcinoma. The identification of the variants of lobular carcinoma was a relatively recent discovery and the information was not available when the 2007 MP/H Rules were written. All of the lobular variants will be included in the next revision of the MP/H Rules.

2012
20081035 MP/H Rules/Histology--Breast: What histology code is used for a single tumor, micropapillary carcinoma with components of mixed ductal and lobular carcinoma?

For cases diagnosed 2007 or later, use rule H16 and assign code 8522 [Duct and lobular carcinoma].

Micropapillary is specific duct type (see Table 1).

 2008
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