Last reviewed 08/2021

A spontaneous pneumothorax is the spontaneous occurrence of air or gas in the pleural space (1).

It is the most common form of pneumothorax and often occurs in young, thin men.

Spontaneous pneumothorax can be divided into:

  • primary spontaneous pneumothorax (PSP)
    • no predisposing lung disease or history of thoracic trauma
    • reported incidence is uncertain but it is thought to be approximately 18–28/100image000 for males and 1.2–6/100image000 for females.
  • secondary spontaneous pneumothorax (SSP)
    • an underlying lung abnormality is present (1,2)