Computed tomogram of rounded atelectasis

(A) Chest computed tomogram shows two examples of rounded atelectasis. The upper panel shows a right lower lobe subpleural mass with loss of volume, an adjacent pleural plaque, and a "comet tail". The lower panel shows rounded atelectasis originating from the posterobasal segment of the left lower lobe. A subpleural mass with accompanying loss of volume, pleural thickening, and a so-called comet tail connecting the mass to the hilar structures are characteristic for this diagnosis.
(B) Graphic representation of rounded atelectasis. A cleft-like invagination of visceral pleura isolates a subsegment of lung that forms a subpleural mass. The bronchi and vessels that connect the mass to hilar structures are pulled into the area of atelectasis and form a so-called comet tail.