1. The concept of endobronchial tuberculosis Endobronchial tuberculosis, also known as bronchial tuberculosis, refers to tuberculosis occurring in the trachea, bronchial mucosa and submucosa. The most common route of infection for adult bronchial tuberculosis is direct implantation of Mycobacterium tuberculosis into the bronchial mucosa, followed by invasion of the bronchial mucosa through the peribronchial tissues by intrapulmonary lesions. In children, bronchial tuberculosis is most often caused by adjacent mediastinal lymphatic tuberculosis encroaching on the bronchi and causing endobronchial tuberculosis. 2. Diagnosis and differential diagnosis Bronchial tuberculosis often occurs in younger patients with slow onset and common symptoms: cough, sputum, low-grade fever, night sweats, dyspnea, weight loss, hemoptysis, etc. Some patients may also have shortness of breath and limited stridor due to bronchial stenosis. In addition to the above clinical features, the main diagnostic methods for the diagnosis of endobronchial tuberculosis include the following: (1) Bacteriological examination A positive bacteriological examination is the “gold standard” for the diagnosis of tuberculosis. Conventional methods include sputum microscopy with antacid/fluorescent staining, sputum culture of Mycobacterium tuberculosis and, in children, culture of Mycobacterium tuberculosis in gastric fluid. The positivity rate of sputum alone is not high due to poorly draining bronchial tubes, the difficulty of expelling necrotic material containing Mycobacterium tuberculosis, the location of lesions such as submucosal infiltrates, and the characteristics of lesions such as proliferative lesions. Bacteriological and histological examination through endobronchial sampling by transbronchoscopy is the most important means to diagnose endobronchial tuberculosis. Brush smear, bronchial flush smear culture, and postoperative sputum smear are common methods of sputum bacteriological examination, among which histological examination is of greater diagnostic value for endobronchial tuberculosis with negative bacteriological examination. Histopathological changes are mainly caseous and non-caseous granulomas with epithelioid and lymphocytic infiltration. (2) Tuberculosis immune-related tests Common tests such as tuberculosis antibody and T-spot test, positive test results indicate previous tuberculosis infection or current tuberculosis infection, where a strong positive or high T-spot value often indicates a higher probability of tuberculosis infection. The diagnosis of tuberculosis can be confirmed based on clinical symptoms and other tests (such as chest CT, sputum culture). (3) Mycobacterium tuberculosis polymerase chain reaction (PCR) technique Because of the long culture period of Mycobacterium tuberculosis in vivo and the low positive detection rate, it often leads to certain difficulties in clinical diagnosis. The detection of Mycobacterium tuberculosis DNA in tissue specimens is an advanced technical method with good application prospects. (4) Imaging The X-ray chest film of endobronchial tuberculosis is not specific, and is closely related to bronchial, pulmonary, pleural and mediastinal lesions, including pulmonary patchy infiltrative shadow, pulmonary atelectasis or limited emphysema, pulmonary solid lesions, cavitary lesions, enlarged hilar shadow, destroyed lung, etc. In addition, some patients may have no abnormal chest film. The CT features of endobronchial tuberculosis include: the posterior segment of the upper lobe and the dorsal segment of the lower lobe are the preferred sites of tuberculosis; the affected bronchial lesions are extensive, often with multiple branches involved; there are bronchial stenosis, wall thickening, and obstruction; and there are mostly associated with pulmonary tuberculosis and enlarged hilar lymph nodes. The diagnosis of endobronchial tuberculosis is further supported when enhanced scans show circumferential enhancement of lymph nodes or the absence of hilar masses in solid, non-distended lung tissue. In terms of differential diagnosis, endobronchial tuberculosis needs to be differentiated from bronchiectasis, bronchopulmonary cancer, pulmonary fungal disease, pulmonary bacterial infection and pulmonary nodular disease. Treatment of endobronchial tuberculosis: The main purpose of treatment of tracheobronchial tuberculosis is, on the one hand, to cure patients with tuberculosis, reduce the spread of tuberculosis, prevent the occurrence of drug resistance, and prevent the recurrence of tuberculosis. On the other hand, it is to prevent tracheobronchial tuberculosis combined with airway narrowing, occlusion, softening and resulting pulmonary atelectasis, and to correct pulmonary ventilation malfunction. (1) Systemic drug therapy According to the classification of endotracheobronchial tuberculosis into primary, re-treatment and drug-resistant cases, systemic anti-tuberculosis drug chemotherapy is selected according to an effective anti-tuberculosis chemotherapy regimen, as described in the “Guidelines for the diagnosis and treatment of pulmonary tuberculosis” and “Guidelines for the chemotherapy of drug-resistant tuberculosis For details, see the “Guidelines for the diagnosis and treatment of tuberculosis” and “Guidelines for the chemotherapy of drug-resistant TB”. The vast majority of patients have a negative sputum culture after 3 months of chemotherapy, and a course of treatment of 12 to 18 months is appropriate. Relapsed, drug-resistant cases choose a relapsed, drug-resistant chemotherapy regimen with a longer duration than the initial regimen, with MDR-TB and XDR-TB requiring at least 24 months or even longer. Cases requiring interventional treatment to deal with central airway stenosis, occlusion, softening, etc., should extend the application of anti-tuberculosis drugs regardless of whether the full course of anti-tuberculosis chemotherapy is administered. (2) Local drug therapy Local administration of anti-tuberculosis drugs in the airway can make the drugs reach the focal area directly and play a role. Due to the high concentration of local drugs, it can effectively play a bactericidal and antibacterial effect, accelerate the conversion of sputum bacteria, promote the absorption of focal areas in the airway and reduce the occurrence of complications, etc. However, it must be carried out on the basis of effective application of systemic anti-tuberculosis drug chemotherapy. Among them, nebulized inhalation of anti-tuberculosis drugs is a common adjuvant treatment for endobronchial tuberculosis, and nebulized treatment has certain efficacy in reducing bronchial stenosis and improving respiratory symptoms. Local injection therapy through bronchoscopy is also a local treatment method, through which bronchoscopy is used to first aspirate the secretions from the diseased bronchus, and after saline rinsing and aspiration, injecting such as isoniazid and amikacin is more effective for congested edema and proliferative nodular lesions of endobronchial tuberculosis. (3) Bronchial local interventional treatment Currently, the interventional treatment methods for tracheobronchial tuberculosis include: transbronchoscopic airway cryosurgery, balloon dilatation, thermal ablation therapy (laser, high-frequency electric knife, argon knife and microwave, etc.), endotracheal stent placement, etc. The characteristics of different types of interventional techniques are different, and the clinical practice sometimes adopts a combination of multiple methods of comprehensive interventional treatment. The indications for cryosurgery include: granulomatous proliferation and scar stenosis (lumen occlusion) type tracheobronchial tuberculosis, and elimination of regenerative granulomas after airway stent placement. Indications for balloon dilation: large airway scar stenosis such as central airway caused by tracheobronchial tuberculosis, where there is no destruction of the lung endings on that side. Indications for thermal ablation therapy: tracheobronchial tuberculosis of the granulomatous proliferative type. Indications for stenting: severe stenosis of the trachea, main bronchus and other large airways, which makes breathing difficult and seriously affects the quality of life; tracheobronchial tuberculosis with softened walls combined with repeated severe infections of the respiratory tract; central airway scar stenosis that is still difficult to achieve after repeated combined treatments such as balloon dilatation and angioplasty, etc. 4. Surgical treatment: Indications for surgical resection: bronchial tuberculosis combined with airway stenosis and occlusion, resulting in end lung lobar and segmental atelectasis, obstructive infection, poor pulmonary ventilation, after systemic anti-tuberculosis chemotherapy, patients with interventional indications to strengthen the local interventional treatment in the airway, but still can not achieve satisfactory results; airway stenosis and occlusion resulting in destruction of the end lung, repeated obstructive infection, combined with Bronchiectasis with recurrent hemoptysis. Standardized antituberculosis chemotherapy should be administered before surgery. The timing of surgery is very strict, and it is best if preoperative imaging indicates no active lesions in the lungs, and the bronchial mucosa is free of congestion and edema on fibrinoscopy, etc. Non-emergency surgery should be performed after 6 months of antituberculosis treatment. The surgical method should be chosen according to the specific circumstances of the lesion and is often determined by the surgeon according to the condition. In addition, it is advocated that anti-tuberculosis treatment should be continued for 9 to 12 months after surgery to prevent recurrence and restenosis.