- Abnormal presence of air within the pleural space
- Spontaneous pneumothorax
- Traumatic pneumothorax
- Iatrogenic pneumothorax
- Catamenial pneumothorax (due to endometriosis in the chest cavity)
 Imaging Findings
 Plain film
- Outer margin of the visceral pleura and lung is separated from for the parietal pleura and the chest wall by a lucent gas filled space devoid of pulmonary vessels.
- When supsected PTX is not seen on an inspiration view, expiration or decubitus views may be helpful (i.e if you suspect a left pneumothorax, perform a right lateral decubitus view).
Patient #1: Acute onset of SOB
Patient #2: Patient with known PCP presents with acute SOB
Patient #3: Acute desaturation
Patient #4: Right deep sulcus sign