The patient, a 60-year-old female, was admitted to the Department of Respiratory Medicine of Peking University First Hospital on August 3, 2011, with the main reason of “intermittent cough for six months, aggravated by wheezing for one month”. The patient started to have intermittent dry cough six months ago; one month ago, her cough worsened with wheezing, and her symptoms gradually worsened, making her unable to get out of bed during the day and unable to lie down at night. He was diagnosed with bronchial asthma at an outside hospital, and his symptoms did not resolve after treatment. 5 days ago, a chest CT at an outside hospital showed severe external pressure stenosis in the middle and lower trachea, right main bronchial stenosis, left main bronchial occlusion, obstructive left pulmonary atelectasis, and multiple mediastinal lymph nodes enlargement (Figure 1). He was admitted to our department for further consultation and treatment. He had a history of hypertension for 2 years and had smoked for 30 years, 20 cigarettes/day. Physical examination: temperature 36.6°C, heart rate 110 beats/min, respiration 25 beats/min, blood pressure 120/90 mm Hg (1 mm Hg=0.133 kPa). He was sitting up and breathing, with a wheezing appearance. No enlargement of superficial lymph nodes was palpable throughout the body. The trachea was left deviated, the trigeminal sign was visible, and wheezing sounds could be heard. The left lung was turbid on percussion, and biphasic dry rales could be heard in the upper chest. The heart rhythm was uniform, and there were no murmurs in the valve areas. The abdomen was flat and soft with no pressure pain. The liver and spleen were not palpable and there was no edema in both lower limbs. Ancillary tests: carcinoembryonic antigen (CEA) 22.02ng/ml (<5ng/ml), neuroenolase (NSE) 62.76ng/ml (<16.3ng/ml). Arterial blood gas analysis: pH 7.46, partial pressure of carbon dioxide (PaCO2) 32 mmHg, partial pressure of oxygen (PaO2) 91 mmHg, inhaled oxygen concentration 29%. Admission diagnosis: tracheal and right main bronchial stenosis, left main bronchial occlusion, left pulmonary atelectasis, mediastinal lymph node enlargement, lung cancer? Immediate pulmonary function tests showed plateau-like changes in the expiratory phase of the V-V curve, and FEV1 was 24% of the expected value. The patient's dyspnea gradually worsened and the PaCO2 rose to 46.6 mm Hg on repeat arterial blood gas, so non-invasive ventilator positive pressure ventilation was administered, which slightly relieved the patient's symptoms and lowered the PaCO2 to 33.2 mm Hg. The right main bronchial stent was immediately implanted via rigid tracheoscopy under general anesthesia. The upper trachea was seen to be patent under tracheoscopy, while the posterior wall of the middle and lower trachea was compressed and protruding into the lumen, resulting in severe tracheal stenosis, with the BF260 tracheoscope barely passing through; the left main bronchus was occluded, and the right main bronchus was open to external compressive stenosis. The right upper lobe, right middle segment and all subsegments of the bronchus were patent. After measuring the distance of the stenosis from the mirror port through a rigid tracheoscope, a stent advancement device was delivered, and a titanium-nickel alloy stent tailored to the total length of the patient's airway stenosis was released blindly, and then re-entered the tracheoscope to observe that the lower segment of the stent was located in the right middle segment of the bronchus, so the lower segment of the stent was moved to the lower segment of the right main bronchus with a biopsy forceps, and the right upper lobe bronchial opening was completely exposed, and the patient's airway was reopened. After the operation, the patient returned to the ward and was able to walk on the floor after waking up. The next day, a repeat chest CT showed that the narrowed trachea and right main bronchus had been restored to patency. Pulmonary function showed that the plateau-like changes in the expiratory phase of the V-V curve disappeared, and FEV1 increased to 54% of the expected value. Subsequent pathology confirmed by bronchial ultrasound (EBUS) transmural lymph node needle aspiration biopsy (TBNA) was low-differentiated small cell lung cancer, and standard chemotherapy was administered. Discussion Central airway stenosis is a narrowing of the lumen of the trachea, right and left main bronchi and/or right middle segment bronchi due to various etiologies. The main clinical manifestations are wheezing, shortness of breath, chest tightness, cough, and occasionally hemoptysis, which can be easily misdiagnosed as other diseases such as asthma and COPD. In this case, the patient had been misdiagnosed as asthma at the beginning of the course of the disease, and the diagnosis of central airway stenosis was supported by the patient's wheezing appearance, triple concave sign, and restricted dryness on admission; later the diagnosis was finally confirmed by chest CT and bronchoscopy. If central airway stenosis occurs at two or more sites at the same time, it is called complex central airway stenosis, which is often caused by advanced tumors, with rapid disease progression and high mortality rate. In this case, the chest CT showed severe external pressure stenosis of the middle and lower trachea and right main bronchus, occlusion of the left main bronchus, left atelectasis, and lesions involving multiple sites; however, the right upper lobe, right middle segment and its distant bronchus were still functional, so it was decided to place a pre-made stent for the right main bronchus to preserve the function of the right upper lobe and right middle and lower lobes. Due to the critical and life-threatening condition of this patient, immediate relief of his central airway stenosis was required. To minimize the operative time and to provide dilatation and support of the airway, we opted for stenting via rigid tracheoscopy. The value of the rigid scope is that it is an important tool in interventional pulmonology as an interventional access allowing various instruments to enter the airway and perform stent release, ablation therapy and balloon dilation under direct vision, or it can be used in conjunction with a bendable bronchoscope to simultaneously ensure airway patency and provide respiratory support. In addition, general anesthesia during rigidoscopy allows for greater patient safety and comfort throughout the procedure. Metal stent placement is generally used only in patients with severe and life-threatening airway stenosis in advanced malignancy to achieve symptom relief and improve the quality of survival, while it is generally not indicated for benign airway stenosis. In this case, the patient's severe airway stenosis was caused by advanced tumor, so the nickel-titanium memory alloy mesh stent, which is most commonly used in China, was selected. The improvement of the patient's postoperative symptoms, pulmonary function and imaging illustrated the good efficacy of the stent. Because the mesh stent has a large mesh, tumor tissue can pass and grow into the airway and reobstruct the lumen; therefore, combined radiotherapy is needed to treat the tumor itself. In this case, the EBUS-TBNA technique was applied to obtain an extra-luminal airway specimen and the pathological diagnosis was small cell lung cancer, which provided the basis for the next step of chemotherapy and achieved a very good treatment result.