ICD-10 Code C34.12 – Malignant neoplasm of upper lobe, left bronchus or lung (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C34.12 – Malignant neoplasm of upper lobe, left bronchus or lung
What it is
This code identifies a malignant neoplasm located in the upper lobe of the left lung or left bronchus. Use it when documentation specifies that exact anatomic site.
Clinical signs
Clinical features vary; refer to documentation. Commonly recorded findings in lung cancer include cough, hemoptysis, dyspnea, chest pain, or imaging showing a suspicious left upper lobe mass.
When to use this code
Use C34.12 when the provider documents primary cancer in the upper lobe of the left lung or left bronchus. It also fits when pathology, imaging, or operative notes clearly localize the malignancy to that site.
If the record only says “lung cancer” without laterality or lobe, check documentation before assigning this code. Use the most specific site documented, and do not guess from nonspecific wording.
Do not use for
Do not use this code for metastatic disease to the lung, unspecified lung cancer, or malignancy in another lobe. Check documentation if the tumor is described only as bronchogenic carcinoma without location.
Coding tip
Confirm both laterality and lobe in the final diagnosis, pathology, or operative report before coding C34.12.