Silhouette sign 2021-02-24T12:47:22Z The silhouette sign is the absence of depiction of an anatomic soft-tissue border. It is caused by consolidation and/or atelectasis of the adjacent lung, by a large mass, or by contiguous pleural fluid. The silhouette sign results from the juxtaposition of structures of similar radiographic attenuation. The sign actually refers to the absence of a silhouette. The silhouette sign is not always indicative of disease (eg, unexplained absence of right border of heart is seen in association with pectus excavatum and sometimes in healthy individuals). See Figure 67 of Hansell DM, et al., Fleischner Society: glossary of terms for thoracic imaging. Radiology. 2008;246:697-722. Pulmonary imaging sign