ICD-10 Code C34.30 – Malignant neoplasm of lower lobe, unspecified bronchus or lung (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C34.30 – Malignant neoplasm of lower lobe, unspecified bronchus or lung
What it is
This code identifies a malignant tumor in the lower lobe of the lung when the bronchus or lung site is documented but laterality is not specified. Use it for primary lung cancer in the lower lobe, not for metastatic disease.
Clinical signs
Clinical features vary; refer to documentation. Commonly documented findings include a lung mass or nodule on imaging, cough, hemoptysis, chest pain, or dyspnea, but the diagnosis should be confirmed by pathology or clearly recorded clinical assessment.
When to use this code
Use this code when the provider documents a malignant neoplasm in the lower lobe of the lung and does not specify right or left side. It also fits when the bronchus or lung is named without laterality in the lower lobe. Check documentation if the record only says “lung cancer” or gives a different lobe.
Do not use for
Do not use this code for metastatic cancer to the lung, benign lung lesions, or tumors in another lobe. If the side is documented, use the more specific laterality code instead.
Coding tip
Always verify whether the record specifies right or left lower lobe before assigning the unspecified code.