Skin fold in ICU mimicking PTX

Q: What is the most common cause of skin fold mimicking pneumothorax (PTX) in an ICU patient?

Answer:  In ICU most of the bedside chest X-rays are obtained by sliding radiographic plate (cassette) from the side under the patient's back. Skin folds should be suspected in obese patients with no reason to suspect PTX. Few clues to distinguish skin fold from PTX on chest X-ray are:

Skin Folds

• tends to extend beyond the rib cage
• tends to gradually increase in opacity 
• abrupt drop–off at the edge of the fold
• blood vessels extend beyond the fold (can be seen with magnifying/zooming-in the x-ray)

#pulmonary

Reference:

Stark, P, Eber, C. Pneumothorax or skin fold? Clin Intensive Care 1993; 4:45.