ICD-10 Code C34.31 – Malignant neoplasm of lower lobe, right bronchus or lung (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C34.31 – Malignant neoplasm of lower lobe, right bronchus or lung
What it is
C34.31 identifies a malignant neoplasm located in the lower lobe of the right lung or right bronchus. Use it when the record clearly specifies this anatomic site for a primary lung cancer.
Clinical signs
Clinical features vary; refer to documentation. Commonly documented findings include a lung mass or nodule on imaging, cough, dyspnea, hemoptysis, chest pain, or weight loss, but the diagnosis should be supported by the recorded site.
When to use this code
Use C34.31 when the provider documents a primary malignant tumor in the right lower lobe bronchus or lung. It also applies when pathology, imaging, or a specialist note clearly identifies that exact location. If the site is described differently or is uncertain, check documentation before assigning this code.
Do not use for
Do not use this code for metastatic disease to the lung, unspecified lung cancer, or malignancy in another lobe or side. If the record does not confirm the right lower lobe site, check documentation.
Coding tip
Code the most specific documented lung site; laterality and lobe matter, so verify the exact wording before finalizing C34.31.