The radiologic significance of the left pulmonary ligament. Experience with 26 patients.

Pathologic processes confined to or by the left pulmonary ligament present a confusing radiographic appearance. Such processes may simulate pleural scarring, parenchymal scarring, or even left lower lobe collapse. Radiologic awareness of this structure is limited because in the normal state, it is not visualized on either posteroanterior or lateral chest x-ray films. The absence of secondary signs of left lower lobe collapse, together with a process which may extend above the level of the left hilum, is valuable in confirming that such a triangular density seen behind the left cardiac border is disease in or confined by the pulmonary ligament, rather than left lower lobe collapse.