Rounded atelectasis of the lung: diagnosis on conventional radiology and CT

Rounded atelectasis is a radiological diagnosis and has to be differentiated from other mass-like opacities in the dorso (basal) part of the chest. Differential diagnosis must first be made with malignant pleural and pulmonary tumors. Specific radiological features such as irregular pleural thickening and the "comet-tail" sign help to make the diagnosis and to avoid unnecessary surgery. CT may be very helpful but frontal or sagittal conventional tomography will often be more diagnostic.