Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral radiographs of the chest demonstrate normal heart size . The cardiomediastinal silhouette and hilar contours are normal . The lungs are clear . No pleural effusion or pneumothorax . No displaced rib fracture identified . There is a 16 mm nodular density projecting over the rib shadow on the lateral projection anteriorly without correlate on the frontal . Those of unknown etiology
    OUTPUT:
    
1 . No evidence of pneumonia 2 . Subtle nodular density projecting over a rib shadow on the lateral projection anteriorly of unknown etiology . Consider nonemergent repeat radiograph to clarify or if the patient has risk factors , a nonemergent chest CT could be considered .