Water lily appearance in chest X-ray suggestive of:
Bronchiectasis
Bronchopleural fistula
Hydatid cyst
Sequestration cyst of lung
Hydatid cyst is caused by the parasite echinococcus granulosus. It is often associated with hydatid cyst of liver.It is usually single buy multiple hydatis cysts can occur. In chest X-ray a dense homogenous opacity can be seen. A collapsed laminated membrane produces an irregular projections in a fluid level due to rupture of the cyst which shows a characteristic 'water lily' appearance on chest X-ray. Ref : Tsung A. (2010). Chapter 31. Liver. In T.R. Billiar, D.L. Dunn (Eds), Schwaz's Principles of Surgery, 9e.