Multiple nodules in both lungs are not necessarily lung cancer. Lung nodules refer to focal, round-like, increased-density lung shadows smaller than 3 centimeters. Multiple refers to more than 2 to 3 lung nodules, and common causes of multiple nodules in both lungs include pneumonia, tuberculosis, lung cancer, and so on. 1. Pneumonia: If the lungs are infected by bacteria or virus, it may cause inflammation. The lungs are stimulated by inflammation and form inflammatory pseudotumor, which may appear as multiple nodules in both lungs. 2. Tuberculosis: If the lungs are attacked by tuberculosis bacillus, causing tuberculosis, leading to damage of both lungs and formation of caseous necrosis, multiple nodules in both lungs may appear. 3. Lung cancer: If the lungs are attacked by tumor, causing lung cancer, multiple nodules in both lungs may appear. If multiple nodules in both lungs are diagnosed, it is recommended to go to the hospital in time, complete the examination, clarify the cause of the disease and carry out standardized treatment under the guidance of doctors.