ICD-10 Code D49.9 – Neoplasm of unspecified behavior of unspecified site (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D49.9 – Neoplasm of unspecified behavior of unspecified site
What it is
D49.9 is used for a neoplasm when the site is not specified and the behavior is not clearly documented as benign or malignant. It signals an abnormal growth that needs further clarification.
Clinical signs
Clinical features vary; refer to documentation. You may see a mass, lump, or incidental imaging finding, but the record must not identify a definite benign or malignant behavior.
When to use this code
Use D49.9 when the provider documents a neoplasm of unspecified behavior and does not name a site. It is appropriate when the diagnosis is confirmed, but the chart lacks enough detail for a more specific code. Check documentation if the pathology or imaging report later identifies the organ or behavior.
Do not use for
Do not use this code if the lesion is documented as benign, malignant, in situ, or uncertain behavior with a specific site. Also avoid it when a more specific neoplasm code is available.
Coding tip
Query for the site and behavior before defaulting to D49.9.