A patient is diagnosed with metastatic bone neoplasm. The neoplasms will be coded as?

• A. Primary Malignant
• B. Primary Benign
• C. Secondary Benign
• D. Secondary Malignant

Answer: (D)

A cancer that has spread to bone is a metastasis, which means the bone lesion is a secondary malignant neoplasm. The cancer didn’t originate in the bone; it started elsewhere and spread there. In coding, this is labeled as secondary (because it’s not the primary tumor) and malignant (because metastases are cancerous). If the primary site is known, you’d typically code both the primary site and the secondary bone site to reflect the metastasis, but the bone lesion itself is classified as secondary malignant, not primary or benign.