ICD-10 Code C50.91 – Malignant neoplasm of breast of unspecified site, female (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C50.91 – Malignant neoplasm of breast of unspecified site, female
What it is
C50.91 identifies a malignant breast tumor in a female when the site within the breast is not further specified. Use it when the record confirms breast cancer but does not document a more exact quadrant or location.
Clinical signs
Clinical features vary; refer to documentation. Commonly, breast cancer may present as a palpable mass, breast skin change, nipple change, or abnormal imaging finding, but the diagnosis must be supported by the medical record.
When to use this code
Use this code when the provider documents malignant neoplasm of the breast in a female and no more specific breast site is stated. It also fits when the chart says breast cancer, but laterality or exact location is not available. If the record gives a more specific site, code that instead.
Do not use for
Do not use it for benign breast disease, carcinoma in situ, or a breast malignancy with a documented more specific site. Check documentation if the note only says history of breast cancer or suspected lesion.
Coding tip
Assign C50.91 only after confirming female sex and lack of a more specific breast site in the documentation.