Fibrous nodules in the lungs are usually residual lesions left by chronic lung infections that are incompletely absorbed and leave imaging changes in the lungs despite aggressive treatment. Of course, fibrous hard nodular foci caused by tuberculosis and lung tumors cannot be excluded. If tuberculosis is suspected, the hard nodular foci are mostly located in the apical segment of the upper lobe of the lung. Enhanced chest CT can be given to find out whether the foci are enhanced or not, and also to determine whether the tuberculosis is old or active based on whether the patient has had tuberculosis in the past, regular anti-tuberculosis treatment, and regular review of whether the similar foci have been present for a long time. If the fibrous nodules are suspected to be caused by lung cancer, further enhanced CT examination of the chest, percutaneous lung puncture biopsy of the nodules and, if necessary, thoracic surgery for early intervention can be performed to remove the fibrous nodules in order to avoid misdiagnosis and missed diagnosis.