Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: No prior studies are available for comparison . There is mild cardiomegaly , likely accentuated by the AP projection and low lung volumes . Opacification in the medial right lower lobe is of unclear etiology , but may be due to a prominent epicardial fat pad , cardiac enlargement , a pericardial cyst , or hernia . No large focal consolidation . Median sternotomy wires are intact . Incidental note is made of old fractures of the posterior left fourth and fifth ribs , with bony callus .
    OUTPUT:
    
1 . Opacity in the medial right lower lung is of unclear etiology of the may be due to cardiomegaly , a prominent epicardial fat pad , pericardial cyst , or possibly a hernia . Correlation with old films , if obtainable , is recommended . 2 . No large focal consolidation .