Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Within the left lower lobe a masslike opacity is seen . This is new when compared to ___ . The remainder of the lungs are clear . The cardiomediastinal silhouette is unremarkable . No significant effusions or pneumothorax .
    OUTPUT:
    
Left lower lobe opacity has a mass like appearance . This could represent a round pneumonia versus underlying less likely neoplasm . In the setting of infection suggest antibiotic treatment and short interval follow - up in 4 weeks to ensure resolution .