Ginkgo leaf sign | Radiology Signs

Answer:

The ginkgo leaf sign is the branching, fan-shaped lucency produced when gas in subcutaneous emphysema of the chest wall dissects along the fibres of the pectoralis major, outlining the muscle bundles against the surrounding soft tissue. The resulting striated pattern over the upper chest resembles the veined blade of a ginkgo leaf and confirms that the lucency lies in the chest wall rather than in the pleural space or lung. It is an alerting rather than a diagnostic finding, because subcutaneous emphysema is a marker of an air leak that must be explained: pneumothorax, often under tension, blunt or penetrating chest trauma with rib fractures, barotrauma from mechanical ventilation, oesophageal or tracheobronchial rupture, a misplaced or dislodged chest drain, recent thoracic or head and neck surgery, and necrotising soft tissue infection producing gas. The important review points are the presence of an ipsilateral pneumothorax and pneumomediastinum, the position and side holes of any chest drain, the mediastinal contours and the tracheal air column, and CT is used when the source is not evident, since it defines the air leak, the airway and the oesophagus. Extensive subcutaneous emphysema also degrades the radiograph itself, obscuring the lung and mimicking or masking a pneumothorax, which is a practical reason to proceed to CT.

Why is it called so?

The gas outlining the pectoral muscle fibres produces a fan of branching lucent lines like the veins of a ginkgo leaf.

Pathophysiology

Air escaping from an injured airway, alveolus, oesophagus or pleural space follows planes of least resistance. From the pleural space or mediastinum it tracks through the thoracic inlet and along fascial planes into the chest wall, neck and, if the volume is large, into the face, abdominal wall and scrotum. Within the chest wall the gas is constrained by the fascia investing the pectoralis major, so it separates and outlines the individual muscle fascicles rather than collecting as a single lucency, and it is this anatomical constraint that generates the striated, leaf-like pattern. The Macklin effect describes the same phenomenon at the alveolar level, in which air ruptures into the bronchovascular sheath and tracks centrally to the mediastinum before decompressing peripherally.

Alternative names: Ginkgo biloba leaf sign

Other associated named signs: Continuous diaphragm sign and the V sign of Naclerio of pneumomediastinum, and the deep sulcus sign of pneumothorax