Multiple lung cysts are the main finding of a group of diseases called cystic lung diseases. Those diseases will frequently present lung cysts that can be of the same size or not, and may have other lung parenchima alterations in CT scans, like ground glass opacities. Lung function impairment of varying degree is also commonly present at diagnosis. The finding of a isolated, small lung cyst, most of the times does not correlate with any pathology. This kind of cysts can appear in individuals as they age, can be a sequelae of a previous infection or can sometimes be found in assymptomatic smokers.