If the misshapen tumor is in the lungs and obstructs the bronchi or fine bronchioles resulting in pulmonary atelectasis, the bronchial truncation sign may be present on imaging, otherwise it is absent. The bronchial truncation sign is an abnormal description on imaging, especially on chest CT, of pulmonary atelectasis due to bronchial obstruction by the tumor tissue, which is visualized as a sudden truncation of the bronchus in the form of a cupped or funnel shape. Chest radiographs show absent lung texture in the distal segment of the bronchial obstruction. Lung malformation is a tumor-like malformation, which contains all the normal tissue components of the lungs, but the composition, number of tissues, arrangement and differentiation degree of each tissue are different from that of normal lung tissues. It can be single or multiple, and can grow in the lumen of the bronchial tubes or in the lung tissues outside the lumen. If the lung malformation tumor grows in the lumen and obstructs the bronchial lumen, resulting in pulmonary atelectasis, there may be bronchial truncation sign on imaging, while if it only grows in the lung tissue, there is no such manifestation on imaging.