If CT indicates a proliferative foci in the left upper lung, the patient should be asked carefully whether he/she had tuberculosis in the past, whether he/she was given standardized anti-tuberculosis treatment, and whether he/she was dynamically followed up for changes in chest CT during the treatment. If polymorphic changes such as fibrosis, proliferation, calcification, nodules, and cavity formation have occurred, some lesions cannot be completely absorbed after giving standardized anti-tuberculosis treatment and can form proliferative, calcified, and cavernous lesions, especially proliferative lesions are most likely to form. Therefore, the possibility of tuberculosis infection is considered first for proliferative foci in the left upper lung. Other specific diseases, including left upper lung lung abscess, left upper lung inflammatory granuloma, and early left upper lung tumor, may also present with similar proliferative focal changes and require the administration of enhanced CT of the chest. If the proliferative foci nodules are large percutaneous lung aspiration cytologic biopsy can be given to clarify the cytologic diagnosis as early as possible to avoid missed diagnosis and misdiagnosis.