Pediatric primary pulmonary tuberculosis

　　1. Causes of disease

　　Primary tuberculosis is a disease caused by the first invasion of Mycobacterium tuberculosis into the body. There are four types of Mycobacterium tuberculosis: human, bovine, avian, and murine. The types that are pathogenic to humans are human and bovine Mycobacterium tuberculosis. The majority of pediatric tuberculosis in China is caused by human Mycobacterium tuberculosis. Mycobacterium tuberculosis has strong resistance, in addition to its characteristics of acid and alkali resistance, alcohol resistance, and resistance to cold, heat, dryness, light, and chemical substances. Moist heat has a strong bactericidal effect on Mycobacterium tuberculosis, and it can be killed in 30 minutes at 65°C, 10 minutes at 70°C, and 5 minutes at 80°C. Dry heat has a poor bactericidal effect, and it takes more than 20 minutes at 100°C to kill, so dry heat sterilization requires a high temperature and a long time. Mycobacterium tuberculosis in sputum can be killed within 2 hours under direct sunlight, while ultraviolet light only takes 10 minutes. Conversely, it can survive for several months in dark places. If the sputum containing Mycobacterium tuberculosis is disinfected with 5% carbolic acid (phenol) or 20% bleaching powder solution, it takes 24 hours to take effect.

　　2. Pathogenesis

　　1. Modes of transmission

　　(1) Respiratory tract infection: Also known as droplet infection, it is the most common mode of transmission, mainly caused by inhaling droplets containing Mycobacterium tuberculosis or dust floating in the air with the bacteria, which enter the lungs to produce primary lung foci.

　　(2) Gastrointestinal infection: It is often due to drinking milk from a tuberculosis-infected cow that has not been disinfected, or eating food contaminated with Mycobacterium tuberculosis, or sharing eating utensils with tuberculosis patients, which can cause Mycobacterium tuberculosis to enter the gastrointestinal tract, causing primary foci in the throat or intestines. Currently, all fresh milk in China is disinfected, so infection with bovine tuberculosis is rare.

　　(3) Infection through the placenta and mucous membranes: Infection through the placenta can lead to intrauterine tuberculosis, which is often discovered after delivery. The mother has active pulmonary tuberculosis or millet grain tuberculosis before delivery. Congenital pulmonary tuberculosis is very rare, but we have seen two cases of blood disseminated pulmonary tuberculosis at birth. One had cavitary pulmonary tuberculosis before delivery, and the other had millet grain tuberculosis.

　　2. Pathogenesis

　　Mycobacterium tuberculosis reaches the lungs through the respiratory tract, grows in the bronchioles and alveoli, causing tuberculous bronchiolitis, and then forming nodules or tuberculous pneumonia. The primary focus can occur in any part of the lung, but most often in the upper lobe or middle part, the upper part of the lower lobe, with the right lung being more common, often close to the pleura. During the primary infection process, the bacteria reach the local lymph nodes through the lymphatic vessels, causing paratracheal or bronchial lymphadenitis. When the lesions of the paratracheal or bronchial lymph nodes continue to develop, they may even penetrate the tracheobronchial wall to form intratracheal tuberculosis, erode, and compress. If the caseous material of the lymph nodes breaks into the trachea, it can cause disseminated pulmonary lesions.

　　3. Immune Mechanism and Onset of Disease

　　Whether a child develops tuberculosis after the first contact with the tuberculosis bacteria is mainly related to the body's immunity, the virulence, and the number of bacteria. In children with negative tuberculin skin test results, after the first contact with the tuberculosis bacteria, when the bacteria enter the body, they activate T lymphocytes, causing them to proliferate in large numbers. Two to ten weeks later, the body develops a delayed-type hypersensitivity reaction to the tuberculosis bacteria and their metabolic products. At this time, a positive tuberculin skin test can be obtained, and the body also develops immunity. After the T cells in the body are sensitized, when they encounter corresponding antigens or macrophages that have engulfed tuberculosis bacteria, various lymphokines are released, such as macrophage migration inhibitory factor, macrophage activating factor, etc., which can cause macrophages to aggregate around the tuberculosis bacteria. The macrophage activating factor can enhance their ability to phagocytize and kill the tuberculosis bacteria, and the lymphotoxin can also kill the bacteria. With the participation of other immune mechanisms, the focus can be localized. It can be seen that in the process of tuberculosis infection, cell-mediated immunity is involved. Therefore, after infection with tuberculosis, the body not only produces变态反应 (hypersensitivity), but also acquires a certain degree of immunity. Some children, especially infants and young children, due to poor immunity, can directly develop primary pulmonary tuberculosis or millet grain tuberculosis after multiple contacts with a large amount of highly virulent tuberculosis bacteria. Most children, after the initial infection, acquire specific immunity and are generally not prone to disease. However, since children are generally susceptible to tuberculosis, the most effective measure to improve the body's specific immunity to Mycobacterium tuberculosis is to be vaccinated with BCG (Bacillus Calmette-Guérin).

　　4. Characteristics of primary tuberculosis in children

　　(1) The high sensitivity of the body's organs to Mycobacterium tuberculosis, that is, all organs of the body are in a highly sensitive state to Mycobacterium tuberculosis. The manifestations are:

　　① There is a widespread inflammatory reaction around the pulmonary lesions.

　　② The skin and mucosa show non-specific reactions, such as herpetic conjunctivitis; nodular erythema on the lower leg; scrofulous appearance, etc.

　　③ Joints may present transient arthritis, also known as tuberculous rheumatism.

　　④ Serous exudative lesions, manifested as multiple serous peritonitis.

　　⑤ The tuberculin skin test shows a strong positive reaction. These manifestations often occur before the appearance of pulmonary tuberculosis lesions and should be identified in a timely manner.

　　(2) The lymphatic system is widely involved, and the lymph nodes throughout the body may become enlarged. After a long time, adhesions may form, the quality may become hard, or there may be a tendency to caseous necrosis, becoming one of the causes of chronic tuberculosis intoxication and dissemination. Lymph node puncture or biopsy may find tuberculosis lesions and tuberculosis bacteria. The mediastinal lymph nodes may also become enlarged, and lymph node enlargement beside the trachea and bronchus may be found during X-ray examination, which is a common type of primary pulmonary tuberculosis in children. Mesenteric lymph nodes may also be involved and become diseased.

　　(3) There is a tendency for systemic dissemination: it is easy to cause lymphatic and hematogenous dissemination, so disseminated pulmonary tuberculosis, tuberculous meningitis, and other diseases are more common in young children. Early on, millet-like eruptions may be seen on the skin, and scrofula is not uncommon after a long time.

　　(4) Healing method: ends with calcification.

　　1. Progression

　　When the child is young, frequently infected, there is a large amount of bacteria invasion, or the immune function is low, the lesions may progress and deteriorate.

　　2. Deterioration

　　Bacteria spread by hematogenous dissemination can lead to miliary tuberculosis, tuberculous meningitis, or miliary tuberculosis in other organs.

　　1. Symptoms

　　The onset may vary in severity, with mild cases showing no symptoms, often discovered during chest X-ray examination during physical examination, or with mild symptoms of tuberculosis intoxication, such as low fever, slight cough, decreased appetite, weight loss, night sweats, fatigue, etc. There may also be acute onset with high fever, cough, resembling influenza, pneumonia, or skin and mucosal allergic manifestations. In young children, when the enlarged lymph nodes compress the trachea, compression symptoms may occur, and if the recurrent laryngeal nerve is compressed, hoarseness may occur. Cough similar to whooping cough may occur at the intersection of the trachea. If the bronchus is compressed, incomplete obstruction or complete obstruction may occur, leading to local emphysema or poor aeration, even atelectasis. Compression of veins may cause the venous network on one side or both sides of the chest surface to become dilated. When the enlarged lymph nodes compress and erode the trachea to cause lymphobronchial fistula, a刺激性 cough may also occur.

　　2. Physical examination

　　When the lymph node enlargement is not obvious, there may be no special signs. However, when the lymph node enlargement is obvious and compresses the trachea, there may be symptoms of shortness of breath and hypoxia; if it compresses the main bronchus, the local lung percussion may be dull, and the respiratory sound may be low or bronchial breathing sound may be heard.

　　1. Control the source of infection and reduce the opportunities for transmission

　　Positive sputum smear tuberculosis patients are the main source of infection for pediatric tuberculosis. Early detection and rational treatment of sputum smear positive tuberculosis patients are the fundamental measures to prevent pediatric tuberculosis. Family members of infants and young children with active tuberculosis should undergo detailed examinations (such as chest X-rays, PPD, etc.). Regular physical examinations should be conducted for staff in primary schools and kindergartens to detect and isolate the source of infection in a timely manner, which can effectively reduce the opportunity for infants and young children to be infected with tuberculosis.

　　2. Popularize BCG vaccination

　　Practice has proved that BCG vaccination is an effective measure for preventing tuberculosis in children. BCG was invented by the French physician Calmette and Guerin in 1921, hence also known as B.C.G. China stipulates the vaccination of BCG in the neonatal period, and according to regulations, BCG is injected intradermally in the upper arm of the deltoid muscle. The dose is 0.05mg per time. The scratch method is now rarely used. The Ministry of Health notified in 1997 to cancel the BCG re-vaccination plan for children aged 7 and 12. However, if necessary, re-vaccination can still be given to children of that age with negative tuberculin test. BCG vaccination in the neonatal period can be administered on the same day as the hepatitis B vaccine on the opposite arm.

　　Contraindications for BCG vaccination: positive tuberculin reaction; eczema or skin disease patients; convalescence period of acute infectious diseases (1 month); congenital thymus hypoplasia or severe combined immunodeficiency disease patients.

　　3. Preventive chemotherapy

　　Mainly used for the following objects:

　　Children under 3 years of age who have not been vaccinated with BCG and have a positive tuberculin test.

　　Close contacts with patients with open pulmonary tuberculosis (usually family members).

　　Children with recent conversion from negative to positive tuberculin test.

　　Children with strong positive tuberculin test reaction.

　　Children with positive tuberculin test who need to use adrenal cortical hormones or other immunosuppressants for a relatively long period of time.

　　1. Laboratory examination

　　1. Smear and culture

　　Finding acid-fast bacilli in sputum, gastric juice, cerebrospinal fluid, and serous cavity fluids is an important means for diagnosing tuberculosis, but the positive rate is low, only 20% to 30%. For infants and young children, gastric juice can be aspirated in the morning on an empty stomach, and the thick film method or fluorescence staining method can be used to detect tuberculosis bacteria, which can have a higher positive rate than general methods. In addition, the above specimens can be inoculated into guinea pigs for tuberculosis culture. The growth of tuberculosis bacteria is slow, and typical pathological changes appear after 4 to 6 weeks. In recent years, the Bactec460 rapid culture identification system has been applied, which uses a 7H12 mycobacteria culture medium with radioactive nutrients (14C palmitic acid) as the substrate. The growth period of tuberculosis bacteria can be shortened to 1 to 3 weeks, and it takes 9 days to detect tuberculosis bacteria. It can differentiate between tuberculosis bacteria and non-tuberculous mycobacteria. Drug sensitivity tests require an additional 3 to 5 days. In 1991, the Rocheseptichek-AFB system, a two-phase culture technique, was applied to rapidly isolate tuberculosis bacteria, and reports can be issued within 2 to 4 weeks. The L-form of acid-fast bacteria is a variation in the morphology of cells and colonies, which is difficult to culture by routine methods. Acid-fast staining is not easy to be detected. In China, the improved tryptic soybean casein agar medium (TSA-L), rapid protein peptone agar bovine serum medium, and sheep blood medium are used to isolate and culture L-form tuberculosis bacteria. In 1998, L-form tuberculosis bacteria were cultured from 260 patients with recurrent and refractory pulmonary tuberculosis, with a positive rate of 29.6%.

　　2. Detection of Mycobacterium tuberculosis antibodies

　　In the past, detection of antibodies using natural antigens such as PPD (PPD-IgG, PPD-IgM) had poor sensitivity and specificity. In the past decade, significant progress has been made in the detection of Mycobacterium tuberculosis-specific antibodies due to the preparation of purified or semi-purified antigens, with currently commonly used antigens including semi-purified Mycobacterium tuberculosis antigens 5, 6, AOO antigen; semi-purified glycolipid antigens such as glycolipid SAGA1, B1, and C, phenol glycolipid (PGL-Tb1), lip阿拉伯甘露聚糖 (LAM) antigen, thiolipids (SL-Ⅰ, SL-Ⅳ), TB-C-1 antigen, and lipopolysaccharides (LPS) among others; purified antigens include Mycobacterium tuberculosis protein antigens (38kDa, 30/31kDa, 71kDa, 45kDa, 14kDa, 19kDa), recombinant 38kDa Mycobacterium tuberculosis protein.

　　(1) Enzyme-linked immunosorbent assay (ELISA): Used for detecting anti-tuberculosis antibodies in the serum, cerebrospinal fluid, and serous cavity fluids of tuberculosis patients, and can serve as an auxiliary diagnostic indicator. The sensitivity of ELISA using semi-purified antigens is 65% to 85%, the sensitivity for negative sputum smear pulmonary tuberculosis is 53% to 62%, and the sensitivity for extrapulmonary tuberculosis is 34% to 40%, with a specificity of 95%. The application of ELISA with 38kDa purified antigens for detecting antibodies has a sensitivity of 73%, and the sensitivity for negative sputum smear pulmonary tuberculosis is 70%, with a specificity of 98%. The application of ELISA with antigen 5 for detecting specific antibodies in the cerebrospinal fluid of patients with tuberculous meningitis has a sensitivity of 70% and specificity of 100%.

　　(2) Enzyme-linked immunoelectrophoresis technique (ELIEP): This is an immunological technique that combines ELISA with electrophoresis, and is a serological method for auxiliary diagnosis of various forms of tuberculosis.

　　3. Detection of Mycobacterium tuberculosis antigens

　　Detection of Mycobacterium tuberculosis antigens in body fluids using methods such as ELISA, latex agglutination test, and reverse passive hemagglutination test. For example, the application of ELISA to detect 34kDa cytoplasmic protein (antigen 5) of Mycobacterium tuberculosis in cerebrospinal fluid for the diagnosis of tuberculous meningitis has a sensitivity of 80% and specificity of 100%. The double-antibody sandwich ELISA method for detecting 43kDa immunodominant antigen in cerebrospinal fluid, ascites, and pleural effusion has a sensitivity of 100% and specificity of 96%. The collaborative agglutination test for measuring lip阿拉伯甘露聚糖 antigen has a sensitivity of 85% to 90% and specificity of 93%. The immunoblotting technique (Western blot) for detecting Mycobacterium tuberculosis antigens has a sensitivity of 89.7% and specificity of 95.7%, and is diagnostically significant for extrapulmonary tuberculosis and negative sputum smear pulmonary tuberculosis.

　　4. Determination of the structural components of Mycobacterium tuberculosis

　　The method of gas chromatography-mass spectrometry is used to detect the bacterial body structural components of Mycobacterium tuberculosis in serum and cerebrospinal fluid, namely, stearic acid (10-methyl octadecanoic acid), which has high specificity and sensitivity. The frequency pulse electron capture gas chromatography method is used to determine the carboxylic acid of Mycobacterium tuberculosis in cerebrospinal fluid, with a sensitivity of 95% and a specificity of 91%. However, the equipment and technology required are complex and expensive.

　　5. Molecular biological examination

　　DNA probe molecular hybridization: The sensitivity of the DNA probe method for detecting clinical specimens is not high, and it only shows a positive result when the number of bacteria in the sample is 10,000/ml. The acridinium ester-labeled gene probe technology and chemiluminescence detection system replace the enzyme-labeled colorimetric system, which can improve sensitivity and can identify various mycobacteria. It can quickly detect Mycobacterium tuberculosis. The use of bacterial luciferase to detect hybridization signals can improve sensitivity by 100 times.

　　Polymerase chain reaction (PCR): Selectively amplify the gene fragment encoding the MPB64 protein with specificity for the Mycobacterium tuberculosis complex, which can amplify this extremely small DNA sample by tens of thousands of times, and obtain results in a few hours. It is fast, sensitive, and highly specific, but it is prone to produce false positive and false negative results. The specific insertion sequence IS6110 of Mycobacterium tuberculosis is amplified by PCR to detect sputum specimens, with a positive rate of 93%, a false positive rate of 2.9%. In China, nested PCR is used to determine the DNA of Mycobacterium tuberculosis in pathological specimens and sputum specimens, with no false positives. Some people use nested PCR to detect the specific repetitive insertion sequence IS6110 in the peripheral blood mononuclear cells of tuberculosis patients, with a positive rate of 64%, higher than that of sputum smears (32%) and sputum culture (35%).

　　DNA fingerprinting technology: Analyze the specific band spectrum of the restriction enzyme fragments of bacterial chromosomes, such as the DNA insertion sequence IS6110, to identify strains and is used in epidemiological research.

　　Mycobacterium tuberculosis drug resistance gene detection: PCR-single strand conformation polymorphism (PCR-SSCP) analysis, PCR-restriction fragment length polymorphism (PCR-RFLP) analysis, and PCR-DNA sequence determination are used to study the drug resistance genes of Mycobacterium tuberculosis.

　　Gene chip technology: Many DNA probes are fixed in a certain order and arrangement on a solid-phase carrier to form a probe array, which can hybridize with the target DNA to obtain a large amount of genetic information at the same time. In 1999, the United States developed a 16S rRNA gene chip for determining the intraspecies polymorphism of Mycobacterium tuberculosis, which is used to identify Mycobacterium tuberculosis and other non-tuberculous mycobacteria. Another type is a gene chip for analyzing the rpoB gene type of drug-resistant tuberculosis strains, which is used to analyze rpoB gene mutations.

　　6. Erythrocyte sedimentation rate

　　The erythrocyte sedimentation rate can accelerate during the active stage of tuberculosis, and after antituberculosis treatment, the erythrocyte sedimentation rate will gradually decrease, which indicates that there was active lesions previously. The erythrocyte sedimentation rate examination is not specific, and normal erythrocyte sedimentation rate cannot exclude active tuberculosis.

　　7. Perform the following examinations through the fiberoptic bronchoscope

　　Secretions or lavage specimens from the lower respiratory tract can be collected for bacteriological examination, and histopathological examination of bronchial and pulmonary lesions can also be performed. Fine needle aspiration biopsy can be performed under the guidance of B-ultrasound, X-ray, or CT. The fiberoptic bronchoscope itself has an 'irritating' effect, and continuous sputum examination for 3 to 4 days after surgery can increase the detection rate of bacteria in sputum smears.

　　The primary complex can be seen in the lung, with primary focus and enlargement of the tracheal and bronchial lymph nodes, and the lymphangitis image between them is often not obvious, sometimes there may be interlobar pleural reaction shadow, the primary focus can be round or patchy shadow, can occupy a lung segment even a lobe, the density is often uneven, sometimes the primary focus overlaps with the atelectasis shadow, when the marginal sharpness and uniform density of the enlarged lymph nodes around the trachea or bronchus are in a mass-like shape, it is called tumor type, if there is inflammatory infiltration shadow around it, it is called infiltrative type or inflammatory type, tuberculosis of the trachea can cause atelectasis or local compensatory emphysema.

　　Secondly, imaging examination

　　1. X-ray examination

　　Perform anteroposterior and lateral chest X-ray photography, and the lateral film is of great significance for the detection of enlarged lymph nodes or lesions near the hilum.

　　(1) Primary complex: The typical manifestation is the primary focus in the lung, enlargement of the hilum lymph nodes, lymphangitis line shadow connecting the two, forming a dumbbell-shaped bipolar shadow. The size of the primary focus in the lung is not uniform, and the local inflammatory lymph nodes are relatively larger while the primary focus in the lung is smaller, which is the characteristic of primary pulmonary tuberculosis. The range of lung lesions in infants and young children can be relatively wide, occupying one lobe of the lung even a segment of the lung; the range of lung lesions in older children is smaller, mostly small patchy or small circular shadows, and some cases may show local pleural changes. Many children due to the mild inflammation of the lung lesions, the range is small, chest X-ray can not be found, or when visiting the doctor, the lung lesions have been absorbed, only leaving the enlargement of the hilum lymph nodes, so currently, the typical dumbbell-shaped bipolar shadow of primary pulmonary tuberculosis in children on chest X-ray is rare.

　　(2) Tuberculous bronchial lymph nodes: It is the most common manifestation of primary pulmonary tuberculosis in children on chest X-ray, and is divided into three types of manifestations:

　　①Inflammatory type: Also known as infiltrative type, the surrounding lung tissue of the lymph nodes has exudative inflammatory infiltration, and is manifested as a high-density shadow extending from the hilum on the chest X-ray, with blurred edges, which is the shadow of the enlargement of the hilum lymph nodes.

　　②Nodular type: Also known as tumor type, mass type, the surrounding lung tissue of the lymph nodes has less or has been absorbed exudative inflammation, and is manifested as a circular or oval dense shadow in the hilum area on the chest X-ray, with clear edges, protruding from the hilum towards the lung field.

　　③ Minimally sized: This type is easy to ignore and should be paid attention to. It is characterized by small nodular and small patchy shadows around the hilum, disordered hilum shadows and pulmonary vessels, and should be analyzed and judged comprehensively by combining medical history, clinical manifestations, and skin test results.

　　2. Fiberoptic bronchoscopy

　　The spread of tuberculosis lesions to the bronchus causes bronchial tuberculosis. The following lesions can be seen in fiberoptic bronchoscopy:

　　(1) Enlarged lymph nodes compress the bronchus, leading to stenosis of the lumen, or adhesion and fixation to the bronchial wall, limiting mobility.

　　(2) Mucosal congestion, edema, inflammatory infiltration, ulceration, or granuloma formation.

　　(3) In the early stage of lymph node perforation, a mass protruding into the bronchial cavity can be seen.

　　(4) Lymph node perforation leads to the formation of lymph node bronchial fistula, with the perforation mouth protruding like a volcano, red in color, and caseous material excreted.

　　What is good to eat for tuberculosis?
　　① Provide adequate protein and iron. More lean meat, animal liver, tofu, soy milk, etc. should be eaten in the diet. These foods are not only rich in high-quality protein and iron elements but also do not have the drawback of increasing phlegm and fire, which is beneficial for enhancing the physical condition of the patient, improving the body's resistance, and promoting the repair of damaged tissues.
　　② Eat more foods rich in vitamin A, C, and calcium. Foods rich in vitamin A include pork liver, egg yolk, cod liver oil, carrots, chives, pumpkin, apricots, etc.; they have the effect of moistening the lungs and protecting the trachea. Foods rich in vitamin C have anti-inflammatory, anti-cancer, and anti-cold functions, such as jujube, pomelo, tomato, green pepper, etc.; calcium-rich foods can enhance the trachea's resistance to allergies, such as pork bones, green vegetables, tofu, sesame paste, etc. It should be noted that dairy products can thicken sputum, making it difficult to expel, thus aggravating the infection, so the intake of milk and its products should be limited.
　　③ Increase the intake of fluids. Drinking plenty of water is beneficial for diluting sputum and keeping the trachea unobstructed; the daily water intake should be at least 2000ml (including water in food).
　　④ Regularly eating edible mushrooms can regulate immune function. For example, shiitake mushrooms and mushrooms contain lentinan and mushroom polysaccharides, which can enhance human resistance and reduce the occurrence of bronchial asthma.

　　1. Treatment

　　1. Chemotherapy

　　(1) For mild cases, isoniazid (INH) should be used alone, with a dose of 10 to 15mg/(kg·d), for a course of 12 months.

　　(2) The combination of isoniazid (INH) and Sm, Sm 20 to 30mg/(kg·d), for 1 to 3 months, and isoniazid (INH) should be continued for 1 to 1.5 years.

　　(3) If the condition is severe or there is consideration of drug-resistant bacterial infection, rifampicin (RFP) 10mg/(kg·d) should be added on the basis of Sm+isoniazid (INH) treatment for 9 months and pyrazinamide (PZA) 20 to 30mg/(kg·d) for 6 to 9 months.

　　If there are gastrointestinal reactions to rifampicin (RFP), pyrazinamide (PZA) can be used for 9 to 12 months. If the liver function is abnormal, rifampicin (RFP) and pyrazinamide (PZA) should not be used, and ethambutol (EB) 10mg/(kg·d) should be used for 6 months instead.

　　2. Complicated with tuberculous trachea

　　In addition to systemic chemotherapy, using isoniazid (INH) 0.1g + dexamethasone 2mg for nebulized inhalation can promote the absorption of tracheal mucosal inflammation and edema, improve respiratory tract ventilation function, promote the healing of lymphangiectasis, and help restore poor lung aeration or atelectasis as soon as possible.

　　3. Tracheoscopy and treatment

　　If tuberculous trachea causes respiratory difficulty or appears with lobar atelectasis, in addition to adding nebulized inhalation, prednisone (prednisone) 1mg/(kg·d) should be added, and the dose should be gradually reduced and stopped after 2 to 3 weeks, and consider performing tracheoscopy and treatment. When caseous material in the tracheal lymph nodes suddenly erodes into the trachea or bronchus, it can be used as one of the emergency rescue measures.

　　4. Surgical operation

　　For simple tumor-type bronchial lymph node tuberculosis, if the treatment is not effective after intensive treatment or there is a possibility of caseous material erosion, it is advisable to perform lymph node clearance surgery as soon as possible to avoid sudden erosion and asphyxia, which can cause life-threatening situations.

　　II. Prognosis

　　1. Absorption and improvement

　　The prognosis of primary pulmonary tuberculosis is generally good. If the immunity is strong, the treatment is reasonable and timely, the focus can start to absorb within 3 to 6 months. Patients treated for 1 year or more can usually be completely absorbed and healed within 2 years. The healing of the primary focus is mainly calcification, and the presence of calcification indicates that the lesion has been present for at least 6 to 12 months. Calcification is one of the characteristics of pediatric tuberculosis.

　　2. Progression

　　When children are young, suffer repeated infections, have a large number of bacteria侵入 or have low immunity, the lesion can progress and worsen, causing a series of consequences: ①Tuberculous pleurisy; ②The primary focus enlarges, producing cavities and caseous pneumonia; ③Peribronchial inflammation around the bronchial lymph nodes, forming lymph node bronchial fistula, endobronchial tuberculosis, lobar pulmonary lesions, or caseous pneumonia. ④Enlarged bronchial lymph nodes can cause obstructive atelectasis or emphysema.

　　3. Worsening

　　Bacteria spread by hematogenous dissemination can lead to miliary tuberculosis, tuberculous meningitis, or miliary tuberculosis in other organs.

　　4. Stationary

　　The lesion has not been completely absorbed or calcified, but there are no active symptoms.