Rounded atelectasis: a new criterion for benignancy

A malignancy must be considered whenever a mass lesion is encountered on a chest roentgenogram. Unless an unequivocal diagnosis of a benign lesion is made, thoracotomy is usually indicated. Rounded atelectasis, while only having been recently described, is being encountered with increasing frequency. As illustrated by our three cases, radiologic diagnosis of this entity is a major criterion for judging the benignity of a mass and obviates the need for a thoracotomy.