This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infection, Subject name: Medicine
Water -lily sign is seen in 
Select and explain. 
A. Hamartoma, B. Complicated hydatid disease, C. Cavitatory lesion in metastasis of the lung, D. Aspergillosis
B: Complicated hydatid disease
Answer: B: Complicated hydatid disease 
Explanation: (Complicated hydatid disease) (400 Grainger's diagnostic radiology 4th)Hydatid disease of lung - lower lobes affected in 60% cases* Calcification of cyst wall is rare and seen only in 0.7% cases* When a mediastinum, vertebral erosion in addition to rib erosion may occur with posterior mediastinum being affected in 65% cases. May be complicated by bacterial infection after cyst rupturesRadio logical signs* Meniscus / double arch / moon/ cresent sign due to thin radiolucent in upper most part of cyst* Combo sign due to air fluid level inside endocyst and air between pcricyst and endocyst* Collapsed membranes inside the cyst outlined by air causing "serpent' sign"* Completely collapsed crumpled cyst** membrane floating on the cyst produces or Water- Lilly" sign of camalotte* Cyst in cyst sign * *Radiological sign in pulmonary embolism (1562- H16th)* Wester mark sign (unilateral oligemia)* Hampton's hump*** Fleischner lines - long curxilinear densities* Felson's sign (Pleural effusion greater on the left than right side)** - Calcification in "Popcorn" craggy or punctate in Hamartoma