<prompt> Water lily appearance in chest X-ray suggestive of:BronchiectasisBronchopleural fistulaHydatid cystSequestration cyst of lung  <response>: 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, Schwazs Principles of Surgery, 9e. 