ICD-10 Code D43.9 – Neoplasm of uncertain behavior of central nervous system, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D43.9 – Neoplasm of uncertain behavior of central nervous system, unspecified
What it is
This code identifies a central nervous system neoplasm whose behavior cannot be clearly classified as benign or malignant, and the site is not further specified. Use it when documentation states an uncertain behavior tumor of the CNS without a more precise location.
Clinical signs
Clinical features vary; refer to documentation. Patients may present with neurologic deficits, headaches, seizures, or mass-effect findings, but the record should support the presence of a CNS neoplasm and uncertainty about behavior.
When to use this code
Use D43.9 when the provider documents an uncertain behavior neoplasm involving the brain, spinal cord, or other CNS structure, but does not specify the exact site. It is also appropriate when pathology or imaging confirms a CNS tumor, yet malignant or benign behavior is not established. Check documentation if the site is described more precisely elsewhere.
Do not use for
Do not use this code for benign or malignant CNS tumors with confirmed behavior, or when a more specific site code is documented. Do not use it if the record only states a mass, lesion, or suspected tumor without a neoplasm diagnosis.
Coding tip
Query for the exact CNS site and tumor behavior before assigning D43.9.