Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Left lower lobe is completely collapsed . Remainder of the lungs are clear . Cardiomediastinal contours are within normal limits allowing for shift related to lobar collapse . Endotracheal tube is in place , terminating 6 cm above the carina . No pneumothorax or definite pleural effusion .
    OUTPUT:
    
Complete left lower lobe collapse is potentially due to mucous plugging , but fixed endobronchial lesion is also possible such as carcinoid or foreign body . Heart is not she she is at