emphysema affecting the central portion of secondary pulmonary lobules, around the central bronchiole, typically involving the superior part of the lungs or lobes; may be related to inflammation of the bronchioles and to the effects of inhaled dust, which aggregates next to respiratory bronchioles; seen in coalworker's pneumoconiosis and (in mild form) asymptomatic city dwellers. SYN: centriacinar emphysema, proximal acinar emphysema.