Pseudo-pneumothorax: skin fold is an excellent imitator

Description

A 79-year-old hospitalised woman underwent central venous catheterisation for high-calorie infusion. Chest radiography to check the position of the catheter showed a curvilinear line at the lateral zone of the right lung (figure 1A). We suspected pneumothorax and performed CT of the chest. However, it revealed the absence of pneumothorax; the curvilinear mimicked pneumothorax was revealed to be a skinfold (figure 1B).

Figure 1

(A) Initial chest radiograph showed a curvilinear line at the right lateral zone of the right lung. (B) CT of the chest revealed the absence of pneumothorax.

The lateral margin of the skinfold artefact, caused by compression of flaccid back skin against the film, can be sharply outlined by a lucent line.1 This line is an edge enhancement phenomenon at the margin between objects with different contrast or luminance (Mach band effect).

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