The most common pathologic type of peripheral lung cancer is lung adenocarcinoma. Peripheral lung cancer refers to the lung cancer that occurs below the segmental bronchus on chest CT or X-ray. The cause of its occurrence is not clear, among which smoking is the most important risk factor. Its main clinical manifestations are coughing, coughing up sputum, chest tightness, wheezing, blood in sputum, chest pain, while early peripheral lung cancer may have no obvious clinical symptoms. The diagnosis of peripheral lung cancer can be further clarified by obtaining pathological tissues through percutaneous lung aspiration biopsy, surgery and other examinations. Peripheral lung cancer should be differentiated from tuberculosis, inflammatory pseudotumor, misshapen tumor and pneumonia. Warm reminder: If peripheral lesions are detected on imaging, it is necessary to be alert to the possibility of peripheral lung cancer, which needs to be further diagnosed in regular hospitals, and invasive tests such as percutaneous lung aspiration biopsy can be performed to clarify the pathological type if necessary.