ICD-10 Code C50.8 – Malignant neoplasm of overlapping sites of breast (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C50.8 – Malignant neoplasm of overlapping sites of breast
What it is
C50.8 identifies a malignant breast tumor that spans overlapping anatomical sites, so no single breast quadrant or region fully describes the lesion. Use it when documentation states the cancer crosses site boundaries.
Clinical signs
Clinical features vary; refer to documentation. Typical findings may include a breast mass, skin or nipple changes, or abnormal imaging, with pathology confirming malignancy and the overlapping site location.
When to use this code
Use C50.8 when the provider documents breast cancer involving overlapping sites, such as a lesion extending across two or more adjacent areas. It also fits when the record explicitly names “overlapping sites” or an equivalent description. Check documentation if the exact site is unclear.
Do not use for
Do not use this code for a clearly localized breast cancer in a single site, such as a specific quadrant or nipple. Do not use it when the chart does not support overlap; check documentation.
Coding tip
Assign C50.8 only when the overlap is documented; otherwise code the most specific breast site recorded.