[Pseudo-tumoral round atelectasis without known pleural history (apropos of 2 cases)].

The authors recall two cases of round atelectasis without any known pleural past-record. The first showed, on successive X rays, an increase in size of the image. In the second case a pleural effusion occurred after the discovery of a round opacity. They stress the various small radiological signs as a way of including the etiology of a purely mechanical atelectasis among the difficult diagnosis of intraparenchymal round opacities.