Solitary or sporadic pulmonary cysts are part of the normal ageing process, an epidemiological overview suggests.

The analysis of participants of the large Framingham Heart Study identified 7.6% pulmonary cysts from over 2,600 chest CT scans.

The cysts were most likely to be found in those over the age of 40 and appear solitary in the peripheral area of the lower lobes.

They cysts were distinct from emphysema and were not associated with smoking or impairment in measures of spirometry reported the researchers from Brigham and Woman’s Hospital Harvard in Thorax.

“This suggests the pulmonary cysts could be mostly explained by the normal aging process of the lungs,” they wrote.

However multiple pulmonary cysts with its count of five or more may need to be scrutinised for the possibility of cystic lung diseases, they said.