ICD-10 Code C79.5 – Secondary malignant neoplasm of bone and bone marrow (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C79.5 – Secondary malignant neoplasm of bone and bone marrow
What it is
C79.5 identifies metastatic cancer that has spread to bone or bone marrow from a primary site elsewhere. Use this code when documentation clearly states secondary malignant involvement of skeletal tissue or marrow.
Clinical signs
Clinical features vary; refer to documentation. Common findings may include bone pain, pathologic fracture, or imaging evidence of metastatic lesions in bone or marrow.
When to use this code
Use C79.5 when the record documents secondary malignant neoplasm involving bone, bone marrow, or both. It is appropriate for confirmed metastatic disease on pathology, imaging, or specialist assessment. Code the primary cancer separately when documented.
Do not use for
Do not use this code for primary bone cancer, benign bone lesions, or nonspecific skeletal pain without metastatic confirmation. Check documentation if the site is uncertain or if metastasis is only suspected.
Coding tip
Verify the primary malignancy and the metastatic site in the chart before assigning C79.5.