Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is at the upper limits of normal size . The contour of the main pulmonary artery is moderately prominent . The mediastinal and hilar contours appear otherwise unremarkable . There is no pleural effusion or pneumothorax . The lungs appear clear . Bony structures are unremarkable .
    OUTPUT:
    
Borderline cardiomegaly and enlarged main pulmonary artery contour , although with little if any change . Sometimes this appearance can represent a normal variant but the possibility of pathology including pulmonary arterial hypertension can not be excluded .