Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral chest views were obtained with patient in upright position . Analysis is performed in direct comparison with the next preceding similar chest examination ___ ___ . Normal heart size , mediastinal structures , and thoracic aorta unaltered . Pulmonary vasculature is not congested . The previously identified bilateral diffuse small nodular densities predominantly present in the mid lung fields persist . Comparison of the chest examinations in both frontal and lateral views gives the clear subjective impression of regression . The improvement appears to be somewhat more marked on the left side than on the right . No new pulmonary discrete infiltrates can be identified , and the lateral and posterior pleural sinuses remain free . No pneumothorax is identified in the apical area .
    OUTPUT:
    
Improvement of the on previous examinations identified fine nodular pattern consistent with pulmonary alveolar proteinosis . As patient 's previous records including multiple CT chest examinations which also over time demonstrated improvement , it may be considered to perform an additional CT scan to confirm the recent improvement more objectively .