ICD-10 Code D49.3 – Neoplasm of unspecified behavior of breast (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D49.3 – Neoplasm of unspecified behavior of breast
What it is
D49.3 identifies a breast neoplasm whose behavior is not clearly documented as benign or malignant. Use it when the record states an unspecified or uncertain breast tumor and you need a diagnosis code.
Clinical signs
Clinical features vary; refer to documentation. Patients may have a palpable breast mass, imaging abnormality, or biopsy finding, but the key point is that the lesion’s behavior is not yet defined.
When to use this code
Use D49.3 when the provider documents a breast neoplasm of uncertain or unspecified behavior and there is no confirmed benign or malignant diagnosis. It may also apply when a mass is being evaluated and the final pathology or behavior is not stated. Check documentation if the record later clarifies the tumor type.
Do not use for
Do not use this code for clearly benign breast lesions or for confirmed malignant breast cancer. If the chart specifies a different breast neoplasm behavior, code that documented diagnosis instead.
Coding tip
Always code the most specific breast diagnosis documented, and query when behavior is unclear.