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Report Produced: 12/23/2025 06:43 AM

Report Question ID Question Discussion Answer Year
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.

2012
20100098 Primary site/Histology--Heme & Lymphoid Neoplasms: How are these fields coded for a 2008 diagnosis of small B cell leukemia, most consistent with mantle cell leukemia that only involved the bone marrow? See Discussion. A bone marrow biopsy was done on 6/18/2008 and showed only small B cell leukemia, most consistent with mantle cell leukemia. ICD-O-3 does not list a histology code for small B cell leukemia or mantle cell leukemia.

Code the histology to 9673/3 [mantle cell lymphoma] and the primary site to C421 [bone marrow].

Mantle cell lymphoma can present in a leukemic phase. The only code available is for mantle cell lymphoma and the only primary site that could be coded would be bone marrow.

2010
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
20160074

MP/H Rules/Histology--Breast: How should histology be coded for a breast primary with resection final diagnosis of "Ductal carcinoma with neuroendocrine features?" See Discussion.

Should the histology for "Ductal carcinoma with neuroendocrine features" be coded to 8500 (Ductal carcinoma, NOS) or 8574 (Adenocarcinoma with neuroendocrine differentiation)?

Code the histology to 8574/3 for Ductal carcinoma with neuroendocrine features.

Ductal carcinoma is also called "invasive breast carcinoma of no special type." WHO classifies Invasive breast carcinoma with neuroendocrine differentiation as 8574/3.

2016
20130174 MP/H Rules/Histology--Breast: Given that the current MP/H rules do not recognize specific types of lobular carcinoma, should the histology for an invasive pleomorphic lobular carcinoma be coded to 8022/3 [pleomorphic carcinoma] or 8520/3 [lobular carcinoma]? See Discussion. The MP/H rules do not seem to recognize specific types lobular carcinomas. As invasive pleomorphic lobular carcinoma is "a very rare and distinct morphological variant of invasive lobular carcinoma," (ncbi.nim.nih.gov). Is this histology best reflected in code 8022/3 [pleomorphic carcinoma] or 8520/3 [lobular carcinoma]?

Code the histology to 8520/3 [lobular carcinoma].

The 4th Edition of the WHO Classification of Tumors of the Breast now describes five variants of invasive lobular carcinoma. These variants are solid type, alveolar, pleomorphic, tubulolobular, and mixed-type. WHO has not yet proposed new ICD-O codes be assigned to these variants. The upcoming solid tumor (MP/H) revisions will include instructions on coding these variants.

2013
20130010 MP/H Rules/Histology--Skin: How is the histology coded for "infiltrative carcinoma with ductal alterations compatible with squamoid eccrine ductal carcinoma" of the skin?

Code the histology to 8413/3 [eccrine adenocarcinoma]. This is the most specific code available for this diagnosis.

According to our expert pathologist advisor, "The adnexal glands in the skin, sweat (eccrine) glands and apocrine glands, all have ducts which connect the business portion of each gland to the skin surface. Some of the adnexal tumors have features of differentiation which appear to be duct-like, hence the designation 'ductal.'"

In addition, "The 'squamoid' simply indicates some degree of squamous differentiation, but doesn't alter the usefulness of [code 8413/3] because we have no way of coding anything more specific in this case anyway."

2013
20150045

MP/H/Histology--Thyroid:  What is the histology code for primary site of thyroid cancer with the histology of papillary thyroid carcinoma, classical and oncocytic type?

Code the histology to 8342/3, thyroid oncocytic (oxyphillic) papillary carcinoma.

2015
20130093 MP/H Rules/Histology--Lung: What histology code is used for an adenocarcinoma in situ/bronchioloalveolar carcinoma (BAC) of the lung? See Discussion.

Classification of lung malignancies has undergone a change. The bronchioloalveolar carcinoma histology is being replaced by adenocarcinoma in situ and minimally invasive adenocarcinoma, using an evaluation of lepidic growth pattern in the tumor.

The final diagnosis is "adenocarcinoma in situ/BAC" and the comment states, "The findings in the current biopsy are most compatible with low grade malignant lesions which, in this sample, shows features of adenocarcinoma in situ (former bronchioloalveolar adenocarcinoma), given the proliferation of pneumocytes is limited to the alveolar lining with no evidence of invasion. However, classification of the lesion depends, per reference guidelines (Travis et al. J THOR ONCOL 2011 6,(2):244-275), on its size and its overall histologic features, to rule out the presence of an invasive component and therefore can only be performed upon examination of it in its entirety, upon resection." The radiation oncologist staged this T1N0M0, stage 1 BAC.

Code the histology to 8140/2 [adenocarcinoma in situ, NOS].

The comment for this case is consistent with information from the CAP protocol, which says, "The diagnosis of bronchioloalveolar carcinoma requires exclusion of stromal, vascular, and pleural invasiona requirement that demands the tumor be evaluated histologically in its entirety. It is therefore recommended that a definitive diagnosis of bronchioloalveolar adenocarcinoma not be made on specimens in which the tumor is incompletely represented."

This tumor was not completely resected. Therefore, code to adenocarcinoma in situ based on the information provided.

2013
20130197 MP/H Rules/Histology--Urinary System: What is the histology code for a 2007 and later diagnosis of papillary carcinoma of the urinary system organs? See Discussion.

Will histology code 8050 [papillary carcinoma, NOS] be used for cases diagnosed 2007 and later? The MP/H Rule H4 for urinary primaries states to code papillary carcinoma to code 8130, but Rule M6 includes tumors coded to 8050.

The IARC publication Pathology and Genetics of Tumours of the Urinary System and Male Genital Organs uses code 8130 only for papillary carcinoma.

Code the histology to 8130 [papillary transitional cell carcinoma] for cases of papillary carcinoma of the urinary system diagnosed 2007 and later.

Histology code 8050 [papillary carcinoma, NOS] should not be used for papillary carcinoma of the urinary system diagnosed starting in 2007. Rule M6 includes this histology to take pre-2007 cases into consideration.

2013
20110078 MP/H Rules/Histology--Bladder: What is the histology code for "high-grade urothelial carcinoma, plasmacytoid variant"? See Discussion. Per the MP/H Manual, Urinary Equivalent Terms & Definitions, Table 1, plasmacytoid is a specific type of Urothelial/Transitional Cell Tumor. What is the correct histology, and rule used, when a bladder resection pathology report states, "high-grade urothelial carcinoma, plasmacytoid variant"?

Code the histology to 8082/3 [urothelial carcinoma, plasmacytoid].

The Multiple Primary and Histology Coding Rules Manual is the correct source for coding histology for cases diagnosed 2007 or later. Unfortunately, in this case there is no current rule that directs you appropriately to Table 1 from Rule H7 to find this histology combination. We need to add an example under Rule H7 that instructs you to "See Table 1" for an urothelial carcinoma diagnosis that mentions a more specific cell type (e.g., plasmacytoid). We will add a reference to Table 1 in Rule H7 in the updates to MP/H Rules.

2011