The majority of nodules in the left upper lung are clinically benign lesions, such as inflammatory infections, inflammatory pseudotumors, and other occupying lesions. For example, inflammatory nodules of the lung caused by infection with bacteria, including Staphylococcus aureus, Klebsiella, Pseudomonas aeruginosa, fungi, and Mycobacterium tuberculosis. The lesions mainly present with varying degrees of fibrosis and calcification. It is also seen in idiopathic diffuse fibrosis of the interstitial lung and in occupational diseases such as silicosis and pneumoconiosis. Very rarely, nodules in the upper left lung are seen as malignant occupying lesions, i.e. bronchopulmonary carcinoma, alveolar cell carcinoma, etc. Enhanced CT imaging scans can be done, and biopsies of nodules in the lungs can be taken for pathological examination through bronchial fiber endoscopy to clarify the nature of the nodules and to provide early treatment accordingly.