Fibrous foci in the lingual segment of the left upper lobe of the lung are usually suggested by chest radiographs and high-resolution CT of the chest and are clinically common in chronic infectious disease of the upper lobe of the left lung. It is important to consider whether the patient has had tuberculosis in the past, as fibrosis, nodules, hyperplasia, calcification, and pleural thickening are polymorphic changes that occur during standardized treatment of tuberculosis, of which fibrous foci are more common. Therefore, if CT indicates fibrous foci in the lingual segment of the upper lobe of the left lung, it is possible that the patient has had tuberculosis, but it is not currently infectious and does not need to be treated with medication, and only dynamic follow-up of high-resolution CT of the chest is needed to understand the stability of the foci. Fibrous foci in the left upper lobe of the lung can also be seen in lung infections, including conditions such as pneumonia and lung abscesses, and do not generally occur in lung cancer. Therefore, there is no need to be nervous about the occurrence of fibrous foci in the lingual segment of the left upper lobe of the lung, which usually do not require drug treatment but only dynamic imaging follow-up.