ICD-10 Code C39.9 – Malignant neoplasm of lower respiratory tract, part unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C39.9 – Malignant neoplasm of lower respiratory tract, part unspecified
What it is
C39.9 identifies a malignant tumor in the lower respiratory tract when the exact site is not specified. Use it for cancers involving the trachea, bronchus, or lung region when documentation does not name a more precise location.
Clinical signs
Clinical features vary; refer to documentation. Commonly recorded findings include persistent cough, hemoptysis, dyspnea, chest pain, or imaging evidence of a suspicious mass.
When to use this code
Use this code when the record confirms a malignant neoplasm in the lower respiratory tract but does not identify the specific subsite. It is appropriate for initial or ongoing encounters when the provider documents the site only as lower respiratory tract, unspecified. If later documentation names the exact organ, code that more specific diagnosis instead.
Do not use for
Do not use C39.9 when the lesion is benign, in situ, or metastatic from another primary site. Check documentation if the cancer is clearly located in a specific lung, bronchial, or tracheal subsite.
Coding tip
Query for the exact anatomic site whenever the note says “lower respiratory tract” without detail.