Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Cardiomediastinal and hilar contours are unremarkable . Apparent concavity of the inferior aspect of the left mainstem bronchus may represent superimposed structures , but can not exclude an endobronchial lesion . Lungs are clear . No pleural effusion or pneumothorax identified . Incidental note is made of bifid right eighth rib fused with the seventh rib .
    OUTPUT:
    
No evidence of pneumonia . Question of left mainstem endobronchial lesion versus superimposed structures . Could be further evaluated with slightly overpenetrated shallow obliques . Please have radiologist review prior to discharging patient .