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SEER Inquiry System - Report
Produced: 06/04/2026 3:10 PM
Question 20110004
Inquiry Details
References:
#1: 2010 SEER Manual. Appendix C
#2: WHO Class Breast Tumors, 37. 2003
Question:
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?
Answer:
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.
