Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is normal in size . The left atrial appendage is perhaps somewhat prominent , noting a mildly convex contour to the left mid mediastinum . There is no pleural effusion or pneumothorax . Best seen on the lateral view is a patchy opacity projecting over the lower spine . Although it overlaps with the course of the left hemidiaphragm , it does not silhouette the the hemodiaphragm , so it seems perhaps more likely to reside in the right than left lower lobe . Bony structures are unremarkable .
    OUTPUT:
    
1 . Patchy posterior basilar opacity , most likely in the right lower lobe , suggesting pneumonia , although the side is not entirely certain . 2 . Mildly bulging left mid mediastinal contour , suggesting enlargement of the left atrial appendage . Other etiologies could yield this contour too , such as a thymic cyst . Correlation with prior films may be helpful if available clinically .