Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is patchy opacity in the lingula , obscuring the left cardiac border on the frontal view . The lungs are otherwise clear . The hila and cardiomediastinal contours are normal . There is no pneumothorax or pleural effusion . Pulmonary vascularity is normal .
    OUTPUT:
    
Lingular opacity may represent atelectasis , but potentially pneumonia or even aspiration in the appropriate setting . Chronicity is also uncertain ; correlation with prior radiographs may prove helpful in determining acuity .