This patient was referred for chest radiography post transbronchial lung biopsy on the right. The lungs are abnormal demonstrating mixed alveolar/interstitial opacity. There is an impression of a right apical pneumothorax. There is also a suggestion of a small subpulmonic pneumothorax on the right. There is also a narrow lucency following the right heart boder
	The lateral chest image suggests a small subpulmonic pneumothorax on the right (arrowed). The right hemidiaphragm can usually be distinguished from the left hemidiaphragm as follows the right hemidiaphragm is commonly elevated compared to the left the gastric fundus air is sited beneath the left hemidiaphragm The right hemidiaphragm appears to extend anteriorly to the anterior chest wall whereas the left hemidiaphragm appears to lose visualisation at the cardiac border
	An enlargement of the lung apices demonstrates a right sided pneumothorax with the visceral pleural surface of the right lung projected over the third rib (arrowed). Note that there are no lung markings on the right between the second and third rib posteriorly- compare with the left side. It is noteworthy that a pneumothorax will occasionally show improved demonstration on the inspiration rather than the expiration view if expiration moves the lung edge off a rib into a rib interspace.

This 36 year old male presented to the Emergency Department with spontaneous onset of central chest pain and discomfort. This is an erect chest image performed on inspiration. There is complete collapse of the left lung.

An expiration PA erect chest was also performed. This case provides support for performing the PA inspiration view first before proceeding to the expiration view. The converse could also be argued- perform the expiration view first for detection of pneumothorax, then proceed to the inspiration view if required for sizing of the pneumothorax. Comment 1 This case demonstrates the fact that lungs are mostly air- in cases of severe pneumothorax such as this, the lung can be seen to collapse down to a relatively small volume. Comment 2 A colleague has suggested to me that tension pneumothorax is a difficult diagnosis on plain film (unless it is severely in tension). When the lung collapses the most compliant contiguous structures will displace the most- this could be diaphragm or mediastinum or both. This image suggests a degree of tension but, when compared with the inspiration view, the appearance is largely attributable to the phase of respiration. The presence or degree of tension cannot be assessed on the expiration phase.

	This patient presented to the Emergency Department following a motorvehicle accident. There appears to be a right sided pneumothorax (white arrow). There is also a clavicle fracture (black arrow) and a suggestion of subcutaneous emphysema (grey arrow).
	Enlargement of the region of possible pneumothorax suggest that this is a pneumothorax rather than a skinfold. Note that there are no lung markings in the area between the lung and lateral chest wall.

This 96 year old lady presented to the Emergency Department with chest pain. She was admitted and portable/mobile chest radiography was requested. Is there any pathology demonstrated on this image?

The arrows identify a number of pneumothorax-like appearances. Right Lung Lung markings are seen to extend beyond the arrowed structures suggesting that these appearances are associated with skinfolds. Left Lung The bottom arrow identifies a curvi-linear structure that extends inferiorly beyond the lateral chest wall. This represents a skinfold. The other curvilinear structures are also skin folds Important Clues - This is an elderly lady who is likely to have loose skin that has a propensity to fold/wrinkle/pucker producing skinfold artifacts. - The chest soft tissue skin-lines laterally, particularly on the left, suggest loose skin. - The radiography was performed with the patient in a sitting position resting against a hard cassette- this position/technique is notorious for producing skin folds that mimic a pneumothorax. - Bilateral pneumothorax does not fit with the clinical picture.

	This is a portable/mobile supine chest X-ray image on a 24 week gestation premature baby at 27 days post partum. The baby's lungs show signs of hyaline membrane disease. The ET tube tip position is marginal NGT noted Right lung faint linear densities are probably skin folds.
	The baby was reintubated and chest radiography was requested to check the ET tube position. The tip of the ET tube is obscured by overlying metallic artifact but is probably in a good position. The tip of the NGT is in a good position. There is uneven lung density, particularly at the lung bases- this can be a sign of supine pneumothorax. Also ? subtle deep sulcus sign Right arm venous longline noted. Chest is rotated LPO
	There is an intercostal drain on the left with the tip in an apical position The linear marking at the right lung base continues beyond the chest wall and extend up to the right axilla- this is likely to represent a skin fold rather than a pneumothorax. Metallic artifact to left of the carina.