ICD-10 Code D38.1 – Neoplasm of uncertain behavior of trachea, bronchus and lung (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D38.1 – Neoplasm of uncertain behavior of trachea, bronchus and lung
What it is
D38.1 identifies a growth in the trachea, bronchus, or lung whose behavior is uncertain. Use it when pathology or documentation shows the lesion is neither clearly benign nor clearly malignant.
Clinical signs
Clinical features vary; refer to documentation. These lesions may be found on imaging, bronchoscopy, or biopsy, with a report describing uncertain or indeterminate behavior rather than definite cancer.
When to use this code
Use D38.1 when the provider documents an uncertain-behavior neoplasm involving the trachea, bronchus, or lung. It is appropriate after diagnostic workup when the lesion is still not classified as benign or malignant. Code the documented site as written and avoid assuming cancer.
Do not use for
Do not use this code for clearly malignant respiratory tumors or for benign lesions with documented benign behavior. If the record only says “mass,” “nodule,” or “lesion” without uncertain behavior, check documentation.
Coding tip
Match the code to the provider’s exact wording; uncertain behavior must be explicitly documented.