Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single portable view of the chest . There is an opacity identified at the left lung base which is more conspicuous on today 's exam . Elsewhere , the lungs are clear without large effusion , consolidation or pulmonary vascular congestion . The cardiomediastinal silhouette is within normal limits . Degenerative changes seen at the shoulders without acute osseous abnormality .
    OUTPUT:
    
Somewhat linear left basilar opacity potentially atelectasis or scar however repeat suggested when the patient is amenable with PA and lateral films . Otherwise unremarkable exam without acute cardiopulmonary process .