Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral radiographs of the chest demonstrate persistent left apical pneumothorax which is no larger in size as compared to the prior study . Cardiomediastinal and hilar contours are unremarkable . There are no pleural effusions .
    OUTPUT:
    
Left apical pneumothorax is no larger since ___ .