Help with results from CT scan

So I don't know if I was supposed to put this new question in the lung cancer category, but this is the closest topic to my question. I had a CT scan done and here are the findings....


abnormal appearance of the left lung base with focal pleural thickening medially that is low density and measures fluid density, measuring 33x 17 mm in size. mild subsegmental atelectasis of the right lung base.


What can this be caused from, or lead to? Thank you so much 4 taking the time 2 read this.....