Diagnosis Coding for Reconstruction Following Mastectomy

Question:

Our plastic coders are debating ICD-10 coding for reconstruction following a mastectomy. We want KZA to provide some guidance. Should we be reporting breast cancer (C50.-) as primary ICD-10?

Answer:

Thank you for your inquiry.

For breast reconstruction following mastectomy, often, three ICD-10 codes are assigned for this encounter. Let's explore and walk through this below.

• For the primary ICD-10, since the plastic surgeon is performing the reconstruction and not treating cancer with the mastectomy, it would be appropriate to report Z42.1 and not the malignant neoplasm of breast ICD-10.

• As a secondary ICD-10, the plastic surgeon would assign a code for the acquired absence of breast Z90.1- to reflect left, right, or bilateral acquired absence of breast.

• Depending on the timing of the reconstruction, a third ICD-10 of either a malignant neoplasm breast (C50.-) or a personal history of malignant neoplasm (Z85.3) are options to consider.  

  • If this is an immediate reconstruction, a malignant neoplasm of breast C50.- could be reported.

  • If this is delayed reconstruction and the patient has completed all cancer treatment, ICD-10 Z85.3 for a personal history of malignant neoplasm breast could be reported.

Remember - ICD-10 supports the medical necessity of the services and work performed, and documentation should support the ICD-10 codes reported.

*This response is based on the best information available as of 3/27/25.