Lung abscess chest pain in the elderly is caused by inflammatory lesions involving the pleura, and the pain is aggravated during breathing. If the abscess breaks into the pleural cavity, it can form an abscess chest, pneumothorax, or an encapsulated abscess chest due to fibrin wrapping, and the patient has restricted respiratory movements and increased shortness of breath. As cavity-like lesions in the lung are seen in a variety of diseases, attention should be paid to the differential diagnosis, mainly: 1. Bronchopulmonary carcinoma Certain tumor central tissues may undergo liquefaction necrosis due to insufficient blood supply to form cavities, such lesions are mostly solitary, eccentric, with thick walls, nodular or irregular inner walls, mostly without liquid level, and no obvious inflammatory infiltrate around. Patients often have hemoptysis, but there are no acute infection symptoms, so it is not too difficult to differentiate from lung abscess. Cancerous tissue may also obstruct the bronchus and cause secondary infection, resulting in distal formation of lung abscess, which should be distinguished from lung abscess in particular. In patients aged >40 years, the presence of isolated cavity-like lesions in the lungs should be of particular concern. Sputum tumor cytology and fiberoptic bronchoscopy are important for diagnosis. CT of the chest can assist in the diagnosis. 2, pulmonary tuberculosis There are often symptoms of tuberculosis toxicity such as low fever, malaise and night sweats. Infiltrative tuberculosis or caseous pneumonia mostly presents as large solid lobes in the upper lobe, in which there are translucent areas, wall-less cavities, not accompanied by fluid level, and there may be disseminated patchy flocculent shadow on the ipsilateral or contralateral side. Antacid staining of sputum smear may reveal Mycobacterium tuberculosis. Pulmonary cysts combined with infection On X-ray chest film, pulmonary cysts appear as fluid-containing cysts or gas-containing cysts, round or ovoid, well-defined, sometimes there are gas-fluid planes within the gas-containing cysts, and the size of the cysts can change with breathing under fluoroscopy. When secondary infection occurs, there may be high fever, cough and large amount of pus sputum, which need to be distinguished from lung abscess, and the diagnosis will be easily made if the original X-ray chest film is compared. 4, lung isolation disease refers to the developmental malformation of the lung so that part of the lung tissue is separated from the main lung to form a cystic lung mass, especially the intralobular type, the bronchi of the mass can be connected with the bronchial system of the body, often in the local secondary infection. The clinical manifestations are cough, sputum, hemoptysis and fever, etc. Symptoms such as malnutrition and anemia may occur if repeated infections are present. x-ray manifestations are pericystic inflammatory infiltrate is lighter than lung abscess, mostly in the lower part, which can be shown by aortography and magnetic resonance imaging of abnormal arteries from the aorta.