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Question: 20130089 Status

Source 1:   2007 MP/H Rules
Source 2:  

MP/H Rules/Histology--Breast: How is the histology coded when a pre-treatment core biopsy showed ductal carcinoma, but the mastectomy specimen following neoadjuvant chemotherapy showed lobular carcinoma? See Discussion.

11/06/2012 Ultrasound-guided biopsy of the left breast and left axilla showed invasive ductal carcinoma. The patient underwent 6 months of chemotherapy. In 05/2013 the patient underwent a mastectomy that showed invasive lobular cancer, pleomorphic type, with 11 axillary lymph nodes negative.

The histology is coded to lobular carcinoma, NOS [8520/3] because the mastectomy (the most representative specimen) showed only lobular carcinoma.

The MP/H Rules state to code the histology from the most representative tumor specimen examined. Although this patient underwent neoadjuvant treatment, there is no indication that the ultrasound-guided biopsy contained more tumor than the mastectomy. The mastectomy is the most representative specimen and should be used to code the histology.

Code duct and lobular CA 8522/3.

A biopsy produces a small amount of tissue and, in this case, found the invasive duct but not the lobular carcinoma. The chemotherapy will be more effective in shrinking or eliminating the duct carcinoma, which explains why no duct was left when the patient had a mastectomy. In this case, we need to think about the findings and process. The lobular carcinoma was present prior to the chemotherapy. However, from the small sample, only duct was identified in the biopsy. After neoadjuvant chemo, only the lobular was left.

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