Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral views of the chest were obtained . Subtle 7 - mm opacity is seen projecting over the left upper lung , at the level of the anterior left third rib . The right lung is clear . No pleural effusion or pneumothorax . The cardiac and mediastinal silhouettes are unremarkable . No overt pulmonary edema is seen .
    OUTPUT:
    
Subtle left upper lobe , 7 - mm nodular opacity for which further evaluation with nonurgent chest CT is recommended .