Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiomediastinal silhouette and pulmonary vasculature are unremarkable . The lungs are grossly clear aside from a nodular opacity in the left midlung . This may represent a vessel , though nodular opacity is not excluded . There is no pleural effusion or pneumothorax . No subdiaphragmatic air is identified .
    OUTPUT:
    
1 . Possible left mid lung nodule . Consider obliques views versus nonemergent chest CT to further assess . 2 . Otherwise no acute abnormality .