ICD-10 Code D49 – Neoplasms of unspecified behavior (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D49 – Neoplasms of unspecified behavior
What it is
D49 is used for a neoplasm whose behavior is not yet determined as benign, malignant, or in situ. It signals that the provider has identified a tumor, but the final pathology or clinical classification is still unclear.
Clinical signs
Clinical features vary; refer to documentation. Commonly, records describe a mass, lesion, or growth with uncertain behavior, often pending biopsy, imaging follow-up, or specialist review.
When to use this code
Use D49 when the documentation states a neoplasm is of unspecified behavior and no more specific behavior code is supported. It is appropriate when the clinician has not yet confirmed whether the lesion is benign or malignant. If pathology later clarifies the diagnosis, update coding to the confirmed behavior.
Do not use for
Do not use D49 when documentation identifies a benign, malignant, or in situ neoplasm. Check documentation if the record gives a more specific site-based code or a confirmed histologic classification.
Coding tip
Code the most specific documented neoplasm behavior available, and query the provider when the behavior is unclear.