Chest Imaging

Asbestos-related focal lung mass

(rounded atelectasis), is a form of lung collapse which has a definite association with asbestos exposure. This condition was first described in older German and French literature in conjunction with collapse therapy for tuberculosis. Blesovsky was the first to use the term folded lung referring to an extensive lung folding due to a fibrous membrane on the costal surface of the visceral pleura. The term rounded atelectasis was first introduced by Hanke who also described in detail a hypothesis for the pathogenesis. According to this author, pleural effusion causes an area of atelectasis at the lower lung border which is tilted upwards or downwards when the fluid diminishes, producing a mass which consists of atelectatic pulmonary tissue folded around thickened pleural indentations. This lung folding causes curvation of the blood vessels and bronchi. Kretzschmar suggested that contraction and organization of the fibrinous pleura also play a role in the enfolding of the atelectatic part.

Radiographically this lesion presents as a round or oval, pleural based density, lobulated or irregular in contour, often with a curved outline and commonly located along the posterior surface of a lower lobe. This primary density is often accompanied by a second more cone-shaped opacity which has been described as a comet tail. It is caused by blood vessels and bronchi which curve towards the mass. On CT the juxtapleural mass is readily identified and there is a characteristic pattern of divergence of vessels as they approach and merge with the atelectatic mass.

JV