Irregular translucent shadow in the left upper lobe of lung may be lung cancer, or it may be manifestation of tuberculosis cavity, pulmonary herpes, pulmonary cyst and other diseases, which need to be diagnosed by further examination. 1. Lung cancer: lung cancer is a kind of malignant tumor originated from epithelial cells of respiratory tract, due to the proliferation and infiltration of tumor cells, it can lead to the appearance of cancerous cavity in lung tissues, which is manifested as irregularly shaped translucent shadow on imaging. 2. Tuberculosis: Lung tissue necrosis due to Mycobacterium tuberculosis infection, followed by the formation of tuberculosis cavities. Along with the influence of the patient’s ventilation and air exchange function, the tuberculosis cavity will gradually increase in size, which will be shown as an irregularly shaped translucent shadow on the imaging. 3. Pulmonary blisters: the pressure of alveolar cavity rises due to various reasons, the alveolar wall ruptures, and the ruptured alveoli merge with each other to form air-containing cystic cavities with a diameter of more than 1cm, i.e. pulmonary blisters. In the imaging examination, pulmonary blisters are often manifested as irregularly shaped translucent shadows. 4. Lung cysts: lung cysts are benign lesions, the cystic cavity can be gas or contain a small amount of liquid. If the cystic cavity is full of gas, the imaging may show an irregularly shaped translucent shadow; if there is a small amount of liquid in the cystic cavity, the imaging may show a “gas-liquid flat” appearance. In daily life, we should pay attention to appropriate exercise, rest and smoking cessation, if you feel unwell, you should go to the hospital in a timely manner, under the guidance of the physician, to identify the causes and give targeted, standardized treatment.