The possible causes of bronchial interruption in the left lower lobe of the lung are left lung pneumonia, lung cancer and other causes. 1. Pneumonia: after the lungs are infected by bacteria, the lesion pattern varies when different lung lobes and lung segments are involved, and the involved lung segments show flaky or triangular dense shadows. Involvement of the whole lung lobe shows a large dense shadow bounded by interlobular fissure. When complicated by sputum, sputum will form embolus, blocking the distal bronchial tracts, and there will be interruption of bronchial tubes. 2. Lung cancer: when lung cancer appears, CT can clearly show that there are masses inside and outside the bronchial lumen, irregular wall and “rat-tail” narrowing, “conical shape” and “cupping” of the lumen. truncation. The tumor mass involves the bronchi and gives a realistic image. On imaging, the bronchi appear truncated. If there is an interruption of the left lower lung bronchus, you need to seek medical attention as soon as possible to avoid serious complications.