ICD-10 Code C50.9 – Malignant neoplasm of breast of unspecified site (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C50.9 – Malignant neoplasm of breast of unspecified site
What it is
C50.9 identifies a malignant breast tumor when the documentation does not specify a particular breast quadrant or site. Use it only when the record confirms breast cancer but gives no more precise location.
Clinical signs
Clinical features vary; refer to documentation. Commonly recorded findings include a breast mass, skin or nipple changes, or abnormal imaging and biopsy results confirming malignancy.
When to use this code
Use C50.9 when the provider documents breast cancer without naming the upper outer quadrant, lower inner quadrant, or another specific site. It also fits when pathology confirms malignancy but the anatomic site remains unspecified in the chart.
Do not use for
Do not use this code if the record identifies a specific breast location; choose the more precise C50.- code instead. Check documentation if the diagnosis is benign, in situ, or uncertain.
Coding tip
Query the provider when breast cancer is documented but the site is missing, because a more specific code may be available.