A large right-sided spontaneous pneumothorax. An arrow indicates the visible edge of the collapsed right lung.
<a href="//commons.wikimedia.org/wiki/User:Jmh649" class="mw-redirect" title="User:Jmh649">James Heilman, MD</a>
CC BY 3.0
<span class="int-own-work" lang="en">Own work</span>