Simulated paraspinal tumor or abscess by rounded atelectasis of the lower lobe.

Lower lobe atelectasis may simulate paraspinal tumor or abscess when margins of the completely collapsed lobe become rounded laterally and the inferior edge separates from the diaphragm. We believe this unusual appearance relates to (1) influence of the pulmonary ligament and (2) total collapse of the lobe to its minimum possible volume. Three cases of different etiologies are herein presented.