Q&A: Malignant inflammatory neoplasm of the breast

Q: In the 2026 ICD-10-CM update, in the neoplasm chapter there are some added specific codes for inflammatory neoplasm of the breast. How do those differ from other types of breast cancer?

A: Inflammatory breast cancer is pretty rare. It accounts for only about 1%-5% of all breast cancers. And although it is a type of invasive ductal carcinoma, its symptoms, outlook, and treatment are different.

It causes symptoms of breast inflammation like swelling and redness, which is caused by the cancer cells blocking the lymph vessels in the skin, causing the breast to look inflamed. It differs in its presentation in that it often does not cause a lump, which we would typically think of in breast cancer, and sometimes doesn’t show up on a mammogram.

It occurs in the younger female population most commonly. It is seen in those that may be considered overweight or obese and it's very aggressive and can spread quickly. Given the fact that it sometimes just shows up as the breast being inflamed, the first diagnosis sometimes can be in the advanced stages and about one-third of cases have already spread when it's diagnosed.

That is why it's so important to have specific codes for this particular type of breast cancer. The codes associated with this type of cancer are:

• C50.A0 (Malignant inflammatory neoplasm of unspecified breast)
• C50.A1 (Malignant inflammatory neoplasm of right breast)
• C50.A2 (Malignant inflammatory neoplasm of left breast)

Editor’s note: This Q&A originally appeared in JustCoding. This information was provided by Shannon McCall, RHIA, CCS, CCS-P, CPC, CEMC, CRC, CCDS, CCDS-O, during the webinar, “JustCoding’s 2026 ICD-10-CM Updates: What’s New to the Mix?