Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral chest radiographs demonstrate and unchanged cardiomediastinal silhouette , with mild cardiac enlargement . Mild interstitial prominence is likely related to the patient 's sickle cell disease . There is a new retrocardiac opacity , which could represent a sickle crisis or pneumonia . A 3 mm nodule in the left lung apex is unchanged dating back to ___ . There is no pleural effusion or pneumothorax . The bones appear somewhat dense and there are H - shaped thoracic vertebrae , also consistent with the patient 's sickle cell diagnosis .
    OUTPUT:
    
Retrocardiac opacity concerning for sickle crisis or pneumonia . Clinical correlation advised .