Imaging description

Subcutaneous emphysema on chest radiographs appears as radiolucent striations that outline muscle fibers or as irregular, ill-defined lucencies.

Importance

Subcutaneous emphysema itself does not require treatment. However, subcutaneous emphysema may be the main or initial presenting sign of serious underlying pathology that does require treatment (Figure 33.1).

Subcutaneous emphysema can also spread along fascial planes and extend to other parts of the body including the head, neck, extremities, and abdomen. Hence, subcutaneous emphysema in one body region may occur from injury to another body region that might not be initially imaged.

Typical clinical scenario

Subcutaneous emphysema is a common radiographic finding in emergency patients. Causes of subcutaneous emphysema of the chest wall include chest wall infection, blunt trauma with injury to the respiratory or gastrointestinal tract, and penetrating injuries [1]. In one series by Marti de Gracia and colleagues, the most common etiology was trauma [2]. Chest wall subcutaneous emphysema is commonly associated with pneumomediastinum and pneumothorax. Thus, signs of pneumomediastinum and pneumothorax should be sought if there is subcutaneous emphysema. There are also iatrogenic causes of subcutaneous emphysema, such as surgery, and placement of tubes and intravenous catheters. A focused clinical history is necessary to determine the iatrogenic cause of subcutaneous emphysema.