Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart size is borderline enlarged . The mediastinal and hilar silhouettes are unremarkable . The lung volumes are preserved ; however , there are diffuse generalized increased interstitial markings . There is no pleural effusion , pulmonary edema , or pneumothorax .
    OUTPUT:
    
Increased interstitial markings which may represent early interstitial or fibrotic lung disease . Especially given extensive smoking history , CT scan is recommended to better characterize these findings .