Which imaging sign is associated with an echinococcal cyst?

The water lily sign is associated with echinococcal cysts and is characterized by the presence of a floating membrane within the cyst. This sign is evident when the cyst has been infected or has undergone changes, leading to the formation of a layer of membranes that can move freely within the cystic space and appear like water lilies on ultrasound. The presence of this sign is crucial for diagnosing an echinococcal cyst, as it indicates the cyst's structural changes and the involvement of the parasite.

In contrast, other signs listed are associated with different conditions or types of lesions. For example, the Fleischner sign is often related to pulmonary conditions, while the string of pearls sign typically refers to the appearance of small ovarian cysts or follicles. The double contour sign is associated with conditions involving joint effusions or certain types of edema. Therefore, understanding the water lily sign's specific relevance to echinococcal cysts is essential for accurate diagnosis in sonography practice.