Rounded Atelectasis

Fig. 1: Lateral chest radiograph of a 77-year-old man, status post recent CABG, shows a round subpleural opacity (red star) in the posterior aspect of the lower lobe. There are small bilateral pleural effusions, left (yellow star) greater than right.
Fig. 2: Axial CT image of the same patient shows a subpleural "masslike" opacity (red star) in the posterior left lower lobe with curvilinear opacities connecting the inner part of the "mass" to the pulmonary hilum (arrows). There is associated volume loss of the left lower lobe and associated left pleural effusion (yellow stars).

Facts:

• Rounded atelectasis is an unusual form of lung collapse that can simulate lung neoplasm on chest radiography
• Commonly occurs in patients with pleural effusions/thickening
• Mostly attributed to asbestos exposure, but other causes have been identified (i.e. TB, infarction, trauma, uremia, postoperative)
• Men more common than women, average age 60 years
• Pathology = thickened visceral pleura with folding of underlying lung parenchyma. No discrete mass
• FNA is usually unnecessary given characteristic imaging findings

Radiologic Findings

• Rounded, oval (less commonly irregular) subpleural mass
• Curvilinear opacities connecting the mass to pulmonary hilum (Comet-tail sign)
• Volume loss of affected lobe (most common in posterior lower lobe)
• Associated pleural thickening

Reference:

Batra P, Brown K, Hayashi K, Mori M. Rounded atelectasis. J Thorac Imaging 1996;11:187-197.