The Radiologic Significance of the Left

‘]jlhe number of reports of pathologic processes involving the left pulmonary ligament (the triangular ligament) are few.’3 When present, such processes are frequently mistaken on chest x-ray films for other abnormal conditions. The pulmonary ligament produces no discernible shadow on either the posteroanterior or left lateral projection on a normal chest x-ray film. The radiographic significance of the left pulmonary ligament was first described by Rabinowitz and Wolfe1 in 1956. Few subsequent reports2’3 have described pathologic processes of this structure. These reports,2’3 dealing with posttraumatic pneumatoceles of the left pulmonary ligament, helped to elucidate the confusing radiographic appearance resulting from abnormalities of this structure. We have recently encountered 26 cases in which a triangular or linear density behind the left cardiac border proved to be a pathologic process within or confined by the left pulmonary ligament. The presence of left lower lobe collapse was the initial radiographic impression in several of these cases.