<num>. rapid progression of complex right upper lobe opacity. such rapid change favors an infectious process over neoplasm, but followup radiographs after antibiotic therapy are recommended to document resolution. if persistent, ct of the chest would be recommended <num>. pulmonary vascular congestion. bilateral interstitial opacities may reflect interstitial edema in this setting, but an atypical pneumonia is also possible <num>. small bilateral pleural effusions