Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Nodule seen at the left lung base on prior exam is compatible with nipple shadow . Lungs are otherwise clear . Cardiomediastinal silhouette is within normal limits . Severe degenerative changes seen at the right shoulder . No acute osseous abnormalities . Pectus excavatum again noted .
    OUTPUT:
    
Nodular opacity at the left lung base is compatible with nipple shadow .