Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a left retrocardiac opacity with air bronchograms consistent with pneumonia . No pleural effusion or pneumothorax . The lung volumes are normal . Heart is normal size . There is no pulmonary edema . The mediastinal and hilar contours are unremarkable .
    OUTPUT:
    
Left lower lobe pneumonia . Followup radiographs after treatment are recommended to ensure resolution of this finding .