There are three clinical types of tuberculosis depending on the number, virulence, route, frequency, interval and immune status of the organism: ① acute hematogenous tuberculosis (a large number of tuberculosis bacilli enter the bloodstream at one time or within a short period of time) ② subacute hematogenous tuberculosis (a small number of tuberculosis bacilli enter the bloodstream) ③ chronic hematogenous tuberculosis (a small number of tuberculosis bacilli enter the bloodstream over a long period of time) The most common type of tuberculosis in children is acute disseminated tuberculosis.) The most common form in children is acute disseminated tuberculosis; older children and adults often present with subacute or chronic disseminated tuberculosis. Most acute disseminated pulmonary tuberculosis is characterized by “triple homogeneity”, i.e., corn nodules of uniform size, density, and distribution, some of which are accompanied by patchy, striated, and/or cavernous shadows. Pulmonary CT: Acute hematogenous pulmonary tuberculosis shows corn nodules of 1-3 mm in diameter with uniform density and distribution, while subacute and chronic patients show nodules of 3-7 mm in size with heterogeneous density and distribution, mainly in the upper and middle lung fields. Most of the nodules had well-defined borders, but some showed blurred borders; the nodules were randomly distributed in the lobules, interlobular septa, and subpleural areas of the lungs. Some patients have patchy, fibrous-striped and/or cavernous shadows, enlarged mediastinal and/or hilar lymph nodes, and varying degrees of pleural effusion or pleural thickening on CT. Sputum smear or culture of Mycobacterium tuberculosis: A positive sputum smear or culture of Mycobacterium tuberculosis is the gold standard for the diagnosis of tuberculosis. However, the sputum positivity rate of blood-borne tuberculosis is only about 30%. Moreover, sputum positivity is affected by many factors, such as improper selection of sputum specimens, low number of sputum checks, intermittent excretion of bacteria from the lesion, and obstruction of the draining bronchus. Fiberoptic bronchoscopy can directly brush or biopsy from around the lesion, thus improving the bacteriological diagnosis. （A strong positive reaction in a patient under 3 years of age should be considered as active tuberculosis with recent infection. In addition to the absence of tuberculosis infection, a negative nodulin test should be considered in the following cases: it takes 4-8 weeks after tuberculosis infection to establish a full metaplasia, and the nodulin test may be negative before this metaplasia occurs. In patients with immunosuppressive drugs such as glucocorticoids or malnutrition, the nodulin reaction may also disappear temporarily. Severe tuberculosis and various critically ill patients do not respond to nodulin or only appear weakly positive, which is related to the temporary suppression of human immunity and allergic reactions, and may turn positive when the condition improves. Others such as lymphocyte immune system defects (such as sepsis, lymphoma, nodular disease, AIDS, etc.) former or the elderly and physically weak people are often negative for nodulin reaction. IFN-γ in vitro release assay Mycobacterium tuberculosis infection activates the body’s immune system, producing effector T lymphocytes and memory T lymphocytes against Mycobacterium tuberculosis. Therefore, detection of IFN-γ in the whole blood or body fluids of patients after specific antigen stimulation can help in the diagnosis of bacillus-negative tuberculosis. Other tests include routine blood tests, Mycobacterium tuberculosis TaqMan-PCR, PPD skin test, anti-tuberculosis antibodies, and erythrocyte sedimentation rate, which have some reference significance for diagnosis.