Differentiating Pneumothorax from the Common Radiographic Skinfold Artifact.

Pneumothorax can be a critical medical condition. The radiographic curvilinear appearance of pneumothorax can be mimicked by a skinfold artifact. Radiographic differentiation of the two entities is achieved in most cases by careful analysis of the characteristics of the linear shadow and its course. A thin, sharply defined opaque density representing the visceral pleura is the hallmark of pneumothorax. The added density of a skinfold presents as a broad opacity, which is outlined laterally by a sharply defined lucent line as a result of the Mach band effect and adjacent air. Unlike pneumothorax, a skinfold produces a line that does not follow the expected course of visceral pleura. Additional features, such as the absence of increased lucency laterally and the projection of lung markings across the curvilinear shadow, can help in the correct identification of skinfolds. Repeating the chest radiograph or using other imaging modalities can be considered in difficult cases.