Rounded atelectasis and fibrotic pleural disease: the pathologic continuum.

Although rounded atelectasis was recognized in 1928, its relationship to fibrotic pleural disease almost has gone unnoticed. We present four cases of lobar rounded atelectasis that help to clarify this relationship. Rounded atelectasis is part of the spectrum of fibrous pleural disease. Any portion of lung may become entrapped by the pleural process. When focal areas are involved rounded atelectasis results. When a larger portion of the thorax is involved with this process, lobar rounded atelectasis may occur. Very extensive disease is recognized as fibrothorax.