Thin-walled cavities and thick-walled cavities are two different pathological states of lung formation that are detected by radiographs and CT of both lungs. The difference between the two generally exists in the wall thickness of the cavity within the mass, which is usually ≥3mm for thick-walled cavities and <3mm for thin-walled cavities. Thin-walled cavities are most commonly caused by inflammatory reactions, including infections with bacteria such as Staphylococcus aureus, Klebsiella, Pseudomonas aeruginosa, and Mycobacterium tuberculosis, and are inflammatory changes that can be completely cured with standard anti-inflammatory therapy. In contrast, thick-walled cavities will be common in most patients mainly in malignant tumors, such as bronchial lung cancer, and also in some more serious infections, such as lung abscesses. Usually, the nature of the cavity can be clarified by taking biopsies of the occupying lesion, and the cancer should be promptly removed surgically and treated with radiotherapy and chemotherapy.