ICD-10 Code D48.9 – Neoplasm of uncertain behavior, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D48.9 – Neoplasm of uncertain behavior, unspecified
What it is
D48.9 identifies a neoplasm whose behavior is uncertain, meaning the pathology or clinical record does not clearly show whether it is benign or malignant. Use it when the diagnosis is a tumor of unclear biologic behavior and no more specific site or type is documented.
Clinical signs
Clinical features vary; refer to documentation. Findings may include a mass, lesion, or abnormal growth that prompts evaluation, biopsy, or imaging, but the record does not establish benign or malignant behavior.
When to use this code
Use D48.9 when the provider documents a neoplasm of uncertain behavior without naming a specific site or when the location is not available in the note. It is also appropriate when pathology confirms uncertain behavior but the chart lacks a more precise coded description. Check documentation if the lesion is later classified as benign or malignant.
Do not use for
Do not use this code for benign neoplasms, malignant neoplasms, or lesions with a documented specific behavior code. If the record identifies the organ or site, choose the more specific code instead.
Coding tip
Query for the exact site and final pathology wording before defaulting to D48.9.