An 11-year-old boy suspected of tuberculosis was transferred to our department from a local hospital on November 22, 2021. The patient was 47kg, 140cm tall with a BMI of 23.98. He was HIV-negative and had no previous history or exposure to tuberculosis infection. Parents reported no associated family medical history. He was born full-term and healthy and was BCG inoculated under the National Immunization Program after birth. He presented to a neighborhood hospital on November 12, 2021, for sudden onset of unexplained fever with cough. Chest computed tomography (CT) scan showed left lung consolidation with segmental atelectasis, scattered calcifications in the left upper lobe, and multiple calcifications and enlargement of lymph nodes in the mediastinum and left hilar region (Figure 1A and B). The length of stenosis of the left main bronchus was about 8mm, with about 90% obstruction of the lumen. From these clinical presentations, the patient was highly suspected of pulmonary and left bronchial tuberculosis and was referred to our tuberculosis care center. 
On admission, clinical investigation revealed the onset of symptoms started ten days prior and was sudden with uncertain cause. The patient started with fever accompanied by chills, to the highest of 40 C, shivering, intermittent cough, thick white mucus production, no chest tightness, shortness of breath, or breathing difficulties, and no dizziness, headache, nausea, or vomiting. Physical respiratory system assessment showed reduced thoracic expansion on the left lung. Chest auscultation revealed reduced vocal resonance, and distinct lowered breathing sound without crackling or wheezing, all on the left lung. Sputum GeneXpert MTB/RIF for mycobacterium tuberculosis was positive, detected on a very low bacterial load, and mutation in the rpoB gene conferring resistance to rifampicin was not detected. The T-SPOT test was positive. The patient's anti-TB therapy was initiated with isoniazid, rifampicin, and pyrazinamide on November 24, 2021. Bronchoscopy examination on the following day revealed severe scarring stenosis (grade III) on the left main bronchus, with swollen and inflammatory bronchi. The stenosis was too narrow for a catheter in a 3.8 mm diameter to pass through (Figure 2A). 
Considering the severity of the airway obstruction, we performed a balloon dilation procedure on our patient on November 25, 2021, after getting consent from his parents. A balloon catheter sized 8 mm in diameter, 4 cm in length, and 2.5 atmospheres was placed to pass through the scarring stenosis. The stenosed bronchial segment was stretched open with the high-pressure balloon dilation for 60 seconds (Figure 2B). This was followed by cryotherapy for 60 seconds three times to reduce restenosis. (Figure 2C) The patient was administered the following post-procedure treatment: dexamethasone 5 mg on aerosol nebulization, once per day for a week, isoniazid 0.1 g on topical nebulization, twice per day for two months. A bronchoscopy follow-up examination on November 29 showed the patency of the treated site was good for a catheter of 3.8 mm diameter to pass through smoothly. A build-up of excessive mucus in the bronchi was observed. After clearing up, the catheter can pass to reach the distal bronchi.
Cryoablation was performed on another two occasions on November 29 and December 7, 2021, at the previously treated stenosis site.
A follow-up chest CT scan after six months of systematic anti-tuberculosis treatment showed lumen of the left main bronchus was narrow but unobstructed and patent. The rest of the bronchial tree in the left lung showed good patency. We also observed effective absorption of infiltration previously seen on the left lung (Figure 1C and D).
The patient had a follow-up bronchoscopy examination on May 12, 2022. The procedure showed the previously dilated scarring stenosed segment on the left main bronchus was still relatively narrow but with good patency and lumen diameter allowing the smooth passage of a 3.8mm diameter catheter (Figure 2D).
The patient was closely monitored over the course of his anti-TB treatment with clinical follow-up every month, chest imaging examination every three months, and bronchoscopy therapy when deemed necessary. The last follow-up assessment was in August 2022. He had a good treatment response and is now leading a normal life.