ICD-10 Code C79.4 – Secondary malignant neoplasm of other and unspecified parts of nervous system (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C79.4 – Secondary malignant neoplasm of other and unspecified parts of nervous system
What it is
This code identifies metastatic cancer involving parts of the nervous system that are not separately specified. Use it when documentation shows a secondary malignant tumor in nervous tissue or related nervous system structures.
Clinical signs
Clinical features vary; refer to documentation. Findings may reflect neurologic involvement such as focal deficits, pain, sensory changes, or other signs of metastatic disease, but the record must clearly identify the nervous system site.
When to use this code
Use C79.4 when the provider documents secondary malignant neoplasm affecting an unspecified or other part of the nervous system. It is appropriate when the primary cancer is known elsewhere and the nervous system lesion is metastatic. Code the documented site as specifically as possible.
Do not use for
Do not use this code for primary nervous system cancers or benign tumors. Do not use it when the record only states neurologic symptoms without confirming metastatic disease; check documentation.
Coding tip
Confirm that the chart names the lesion as secondary or metastatic and links it to the nervous system before assigning C79.4.