Differential diagnosis of lung cancer and pulmonary tuberculosis

Lung cancer cases present various clinical symptoms and X-ray signs depending on the location of the tumor, pathological type, and early or late course of the disease, and are easily confused with other lung diseases. Therefore, differential diagnosis of lung cancer, especially early cases, is of great significance for early diagnosis and early treatment.

(1) Pulmonary tuberculoma: It is common in young patients and generally has no obvious symptoms. It is mostly located in the areas where tuberculosis is common, such as the apex, posterior segment and dorsal segment of the upper lobe. On X-rays, the lesions have clear boundaries and may have capsules. The density of the block shadows is uneven. Sparse translucent areas can be seen, which may contain calcification points. There are often scattered tuberculosis lesions in the lungs. In general observation, there are usually no obvious changes. If there is a cavity, it is mostly a central cavity with regular and thin walls. It often needs to be differentiated from peripheral lung cancer.

(2) Miliary tuberculosis: The X-ray signs of acute miliary tuberculosis are similar to those of diffuse bronchioloalveolar carcinoma. Miliary tuberculosis is more common in young people, with symptoms of systemic poisoning such as fever, night sweats, cough, hemoptysis, and weight loss. During X-ray diagnosis, the lesions will be found on the X-ray film as miliary nodules of uniform size, uniform distribution, and low density. In contrast, alveolar carcinoma has nodular disseminated lesions of varying sizes in both lungs, with clear edges, deeper density, and progressive development and spread, often accompanied by progressive dyspnea, chest tightness, and shortness of breath. It can be differentiated by comprehensive judgment based on clinical and laboratory data.

(3) Hilar lymph node tuberculosis: Hilar masses on X-rays may be misdiagnosed as central lung cancer. Hilar lymph node tuberculosis is common in children or the elderly, with symptoms of tuberculosis such as fever, cough, hemoptysis, chest tightness, and shortness of breath. The tuberculin test is often strongly positive. Anti-tuberculosis drug treatment is generally effective. The special X-ray signs of central lung cancer can be identified through tomosynthesis, CT, MRI, and bronchoscopy.

It is worth mentioning that lung cancer can coexist with pulmonary tuberculosis in a small number of patients. Since there are no special clinical manifestations and X-ray signs are easily overlooked, clinical physicians are often satisfied with the diagnosis of pulmonary tuberculosis and ignore the coexisting cancerous lesions, which often delays the early diagnosis of lung cancer. Therefore, for middle-aged and older pulmonary tuberculosis patients, if there are block shadows at the site of pulmonary tuberculosis lesions or other lung fields, and the lung lesions have not improved after anti-tuberculosis drug treatment, and the block shadows have increased or are accompanied by atelectasis of lung segments or lobes, and the shadow of one side of the hilum has widened, etc., the coexistence of tuberculosis and lung cancer should be highly suspected, and further sputum cytology and bronchoscopy should be performed.