C79.81 Secondary malignant neoplasm of breast

Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis.

Applies from C79 Secondary malignant neoplasm of other and unspecified sites

Excludes1 (never code together)

• secondary carcinoid tumors (C7B.-)
• secondary neuroendocrine tumors (C7B.-)

Risk adjustment (HCC)

• CMS-HCC V28: HCC 18 — Cancer Metastatic to Bone, Other and Unspecified Metastatic Cancer; Acute Leukemia Except Myeloid
• CMS-HCC V22: HCC 10 — Lymphoma and Other Cancers
• RxHCC V08: HCC 18 — Secondary Cancer of Lung, Liver, Brain, and Other Sites
• ESRD V24: HCC 10

MS-DRG index

Defines the logic of DRG(s) 582-583 in MDC 09.

Approximate ICD-9-CM (GEMs)

• 198.81 Secondary malignant neoplasm of breast

Diagnosis Index entries for C79.81

• Melanoma (malignant) › metastatic › breast

Nearby codes

• C79.7 Secondary malignant neoplasm of adrenal gland
• C79.70 Secondary malignant neoplasm of unspecified adrenal gland
• C79.71 Secondary malignant neoplasm of right adrenal gland
• C79.72 Secondary malignant neoplasm of left adrenal gland
• C79.8 Secondary malignant neoplasm of other specified sites
• C79.81 Secondary malignant neoplasm of breast (this code)
• C79.82 Secondary malignant neoplasm of genital organs
• C79.89 Secondary malignant neoplasm of other specified sites
• C79.9 Secondary malignant neoplasm of unspecified site